The control is non-destructive. forgings from ferrous and non-ferrous metals. Quality control of stamped forgings Ultrasonic testing of forgings GOST

26.04.2020

GOST 24507-80

Group B09

STATE STANDARD OF THE UNION OF THE SSR

NON-DESTRUCTIVE CONTROL.
FORGINGS FROM FERROUS AND NON-FERROUS METALS

Methods of ultrasonic flaw detection

Non-destructive testing.
Forgings from ferrous and non-ferrous metals.
Ultrasonic methods of slow defection

Introduction date 1982-01-01

APPROVED AND INTRODUCED BY Decree of the USSR State Committee for Standards dated December 30, 1980 No. 6178

REPUBLICATION (March 1993) with Amendment No. 1 approved in May 1986 (IUS 8-86).

This standard applies to forgings made of ferrous and non-ferrous metals with a thickness of 10 mm or more and establishes methods for ultrasonic flaw detection of metal continuity, which ensure the detection of defects such as shells, sunsets, cracks, flocks, delaminations, non-metallic inclusions without determining their nature and actual sizes.

The need for ultrasonic testing, its scope and norms of unacceptable defects should be established in the technical documentation for forgings.

General requirements for ultrasonic testing methods - according to GOST 20415-82.

The terms used in the standard are given in the appendix.

1. APPARATUS AND TEST SPECIMENS

1.1. During the control, the following should be used: ultrasonic pulsed flaw detector, transducers, test or standard samples or DGS diagrams, auxiliary devices and devices to ensure constant control parameters and registration of results.

1.2. During the control, flaw detectors and transducers that have passed certification, state tests and periodic verification in the prescribed manner are used.

1.3. During contact testing of cylindrical forgings with a diameter of 150 mm and less with inclined transducers in the direction perpendicular to the generatrix, the working surface of the transducer is rubbed on the surface of the forging.

When inspecting forgings with a diameter of more than 150 mm, nozzles and supports can be used to fix the entry angle.

1.4. Test and standard samples are used in large-scale production of forgings that are homogeneous in terms of attenuation of ultrasound, when the amplitude fluctuations of the bottom signal inside individual forgings do not exceed 4 dB, and from forging to forging - 6 dB (with equal thicknesses and the same surface treatment).

1.5. DGS diagrams are used in small-scale production or in the control of large-sized forgings, as well as in the case when the fluctuations of the bottom signal exceed the values specified in clause 1.4.

1.6. DGS diagrams are used for testing on flat surfaces, on concave cylindrical surfaces with a diameter of 1 m or more, and on convex cylindrical surfaces with a diameter of 500 mm or more - for a direct probe, and with a diameter of 150 mm or more - for an inclined probe.

1.7. The test specimens shall be made of metal of the same grade and structure and have the same surface finish as the inspected forgings. The test specimens shall be free from defects detectable by ultrasonic testing.

1.8. The amplitude of the back signal in the test specimen shall not be less than the amplitude of the back signal in the forging (with equal thicknesses and equal surface finish) and shall not exceed it by more than 6 dB.

1.9. It is allowed to use test specimens from similar types of alloys (for example, from carbon steel of various grades) provided that the requirements of clause 1.8 are met.

1.10. The shape and dimensions of the control reflectors in the samples are indicated in the regulatory and technical documentation. It is recommended to use reflectors in the form of flat-bottomed holes oriented along the axis of the ultrasonic beam.

1.11. The set of reflectors in the test specimens shall consist of reflectors made at different depths, of which the minimum shall be equal to the "dead" zone of the detector used, and the maximum shall be equal to the maximum thickness of the forgings to be tested.

1.12. The depth steps should be such that the ratio of the amplitudes of the signals from the same control reflectors located at the nearest depths is in the range of 2-4 dB.

1.13. At each depth step in the test sample, reference reflectors shall be made to determine the level of fixation and the level of rejection. It is allowed to manufacture control reflectors of other sizes, but at the same time, the ratio of the amplitudes from the two closest reflectors in size should not be less than 2 dB.

1.14. The distance between reference reflectors in the test pieces shall be such that the effect of adjacent reflectors on the echo amplitude does not exceed 1 dB.

1.15. The distance from the reference reflector to the wall of the test sample must satisfy the condition:

where is the distance along the beam from the input point to the reflecting surface of the control reflector, mm;

- wavelength ultrasonic vibrations, mm.

1.16. The areas of flat-bottomed reflectors should be selected from the following range (corresponding hole diameters are indicated in brackets): 1 (1.1); 2 (1.6); 3 (1.9); 5 (2.5); 7(3); 10 (3.6); 15 (4.3); 20(5); 30 (6.2); 40 (7.2); 50 (8); 70 (9.6) mm.

1.17. The depths of flat-bottomed reflectors (distances from their ends to the input surface) should be selected from the range: 2, 5, 10, 20, 50, 75, 100, 150, 200, 250, 325, 400, 500 mm and then after 100 mm with an error of no more than ±2 mm.

1.18. Test specimens for the control of aluminum forgings are made in accordance with GOST 21397-81. It is allowed to use analogue test specimens made of D16T aluminum alloy for testing other materials using calculators.

1.19. Accuracy and manufacturing technology of control reflectors for a direct transducer - according to GOST 21397-81, for an inclined transducer - according to GOST 14782-76.

1.20. The radius of the test specimen shall be equal to , where is the radius of the forging.

It is allowed to use test specimens of a different radius when the ratio is 0.9<<1,2.

1.21. The use of test specimens with a flat input surface is allowed when testing cylindrical products with a diameter of more than 500 mm with a direct combined transducer and when testing cylindrical products with a diameter of more than 150 mm with a straight double-combined transducer or an inclined probe.

1.22. DGS-diagrams or calculating devices must meet the following requirements:

the division value of the "Signal amplitude" scale should be no more than 2 dB;

the scale division value "Depth of occurrence" should be no more than 10 mm;

the distance along the ordinate axis between the curves corresponding to different sizes of control reflectors should be no more than 6 dB and no less than 2 dB.

2. PREPARATION FOR CONTROL

2.1. During the general technological preparation of production for forgings subject to ultrasonic testing, technological charts of ultrasonic testing are compiled.

2.2. A technological map is compiled for each standard size of a forging. The map contains the following information:

basic forging data (drawing, alloy grade, if necessary - sound speed and attenuation coefficient);

scope of control;

surface treatment and allowances (if necessary, indicate on the sketch);

basic control parameters (sound scheme, transducer types, input angles and operating frequencies, control sensitivity, scanning speed and step);

quality requirements for forgings.

It is allowed to draw up standard control charts combined with one or more of the listed parameters.

2.3. The control flow chart should provide for testing at that stage of the technological process when the forging has the simplest geometric shape and the largest allowance. Control without allowance is allowed if full sounding of the entire volume of metal is ensured. It is recommended to carry out control after heat treatment of the forging.

2.4. Before testing, the surfaces of the forgings from which sounding is carried out (input surfaces) must be machined and have a surface roughness parameter<10 мкм по ГОСТ 2789-73 .

The surfaces of forgings parallel to the input surfaces (bottom surfaces) must have a roughness parameter of 40 µm according to GOST 2789-73.

It is allowed to reduce the requirements for surface roughness, provided that unacceptable defects are detected.

3. CONTROL

3.1. The control of forgings is carried out by the echo method and the mirror-shadow method.

Other methods may be used provided unacceptable defects are identified. Control by the mirror-shadow method is carried out by observing the attenuation of the amplitude of the bottom signal.

3.2. Sounding schemes for forgings of various geometric shapes are established by the technical documentation for testing.

3.3. The scheme of sounding forgings in full is set in such a way that each elementary volume of metal is sounded in three mutually perpendicular directions or close to them. In this case, forgings of rectangular section are sounded by a direct transducer from three perpendicular faces. Cylindrical forgings are sounded by a direct transducer from the end and side surfaces, as well as by an inclined transducer from the side surface in two directions perpendicular to the generatrix (chordal sounding).

3.4. If one of the dimensions of the forging exceeds the other dimension by a factor or more, then the direct transducer is replaced by an inclined transducer. In this case, inclined transducers with the largest possible input angle are used, and sounding is carried out along the largest dimension in two opposite directions.

The value is determined by the expression

where is the diameter of the transducer piezoelectric plate, mm;

- frequency of ultrasound, MHz;

- speed of longitudinal ultrasonic vibrations in the given metal, m/s.

(Revised edition, Rev. No. 1).

3.5. The drawing shows examples of sounding schemes in full forgings of a simple geometric shape, the sign indicates the direction of radiation of the direct finder, the sign indicates the direction of movement and the orientation of the inclined finder.

Examples of sounding forgings of a simple form

3.6. The control is carried out by scanning the surfaces of the forgings, determined by the given scheme of sounding, by the transducer.

The scanning speed and step are set by the technical documentation for control, based on the reliable detection of unacceptable defects.

3.7. The frequency of ultrasound is indicated in the technical documentation for the control. Massive and coarse-grained forgings are recommended to be sounded at frequencies of 0.5-2.0 MHz, thin forgings with a fine-grained structure - at frequencies of 2.0-5.0 MHz.

3.8. The level of fixation and the rejection level must correspond to the levels established by the technical documentation for forgings, with an error of no more than ±2 dB.

3.9. The search for defects is carried out on the search sensitivity, which is set:

with manual control - 6 dB above the fixation level;

with automatic control - such that the defect to be fixed is detected at least 9 times out of 10 experimental soundings.

3.10. During the control, areas are fixed in which at least one of the following signs of defects is observed:

reflected signal, the amplitude of which is equal to or exceeds the specified fixation level;

attenuation of the bottom signal or attenuation of the transmitted signal to or below a given fixation level.

4. PROCESSING AND FORMULATION OF THE RESULTS OF CONTROL

4.1. When defects are detected, their main characteristics are evaluated:

distance to the transducer;

equivalent size or area;

conditional boundaries and (or) conditional length.

If necessary, the defects are classified into extended and non-extended ones and their spatial location is determined.

4.2. The results of the control are recorded in the forging certificate and entered in a special journal, which is drawn up in accordance with GOST 12503-75 with the following additional details:

fixation level;

control dates;

surname or signature of the operator.

If defects are found in the log, their main characteristics are recorded in accordance with clause 4.1 and (or) defectograms.

4.3. Based on the comparison of the results of the control with the requirements of the normative and technical documentation, a conclusion is made about the suitability or rejection of the forging.

4.4. In the normative and technical documentation for forgings subject to ultrasonic testing, the following must be indicated:

fixation level, unacceptable level of bottom signal attenuation and parameters of unacceptable defects (minimum equivalent size or area, minimum conditional length, minimum number of defects in a certain volume), for example:

Defects of an equivalent area or more are subject to fixation.

Defects of an equivalent area or more are not allowed.

Defects of nominal length and more are not allowed.

Defects are not allowed that cause, when controlled by a direct transducer, the back- ground signal is weakened to a level or lower.

Non-extended defects with an equivalent area from to are not allowed if they form an accumulation of or more defects with a spatial distance between the most remote defects equal to or less than the thickness of the forging.

Indicators of technical requirements for forgings based on the results of ultrasonic testing

Direct converter

Angle transducer

Specific

pa-chest-

density of defects in

cluster

4.5. When writing normative requirements for the quality of forgings, it is recommended to indicate the quality group of forgings in accordance with the table. The table shows the values that are used to calculate the unacceptable number of defects in a cluster of sizes according to the formula

When calculating, round down to the nearest whole number.

(Revised edition, Rev. No. 1).

4.6. In forgings assigned to groups 1, 2 and 3, not a single extended defect and not a single defect of an equivalent area or more is allowed. Such a condition is usually satisfied by vacuum melting metals. In forgings assigned to groups 2, 3 and 4, small non-extended defects are allowed (for example, non-metallic inclusions found in some open-hearth steels). In forgings assigned to group 4, some extended defects are allowed, the nominal length of which is less than 1.5.

5. SAFETY REQUIREMENTS

5.1. Ultrasonic flaw detectors are portable electrical receivers, therefore, when using them, safety and industrial hygiene requirements must be met in accordance with the "Rules for the technical operation of consumer electrical installations" and "Safety regulations for the operation of consumer electrical installations", approved by the State Energy Supervision Authority in 1969 with additions and changes in 1971 .

5.2. Persons who have passed the knowledge test of the "Rules for the technical operation of consumer electrical installations" are allowed to work with ultrasonic devices. If necessary, the qualification group of flaw detectorists is established by the company conducting the control, depending on the working conditions.

5.3. Fire safety measures are carried out in accordance with the requirements of the "Model Fire Safety Rules for Industrial Enterprises" approved by the GUPO of the USSR Ministry of Internal Affairs in 1975 and GOST 12.1.004-91.

5.4. The control area must comply with the requirements of SN 245-71, approved by the USSR Gosstroy, as well as GOST 12.1.005-88.

5.5. When using lifting mechanisms at the control site, the requirements of the "Rules for the Design and Safe Operation of Hoist Cranes", approved by the USSR Gosgortekhnadzor in 1969, must be taken into account.

5.6. Additional safety requirements are specified in the technical documentation that defines the technology for testing specific forgings and approved in the prescribed manner.

5.7. During the control, the requirements of GOST 12.3.002-75 and GOST 12.1.003-83 must be observed.

APPENDIX (reference). TERMS USED IN THE STANDARD

APPENDIX
Reference


	Explanation

equivalent size	The size (or dimensions) of a control reflector of a given shape, located in the test sample at a depth closest to the depth of the defect, and giving an echo signal equal in amplitude to the signal from the defect
Equivalent defect area	The area of the end face of a flat-bottomed drilling located in the test sample at a depth closest to the depth of the defect and giving an echo signal equal in amplitude to the signal from the defect
Fixation level	The amplitude level of the echo signal from the control reflector, specified by the normative and technical documentation for forgings, which serves as the basis for fixing the defect:
	by exceeding this level by the signal during the control by the echo method;
	by attenuation of the bottom signal to this level when controlled by the mirror-shadow method
Rejection level (applies only to echo testing)	The amplitude level of the echo signal from the control reflector, specified by the normative and technical documentation for forgings, the excess of which by a signal from a defect serves as the basis for rejecting the forging
Conditional defect boundary	The locus of the positions of the center of the forward transducer or the entry point of the inclined transducer on the input surface, at which the amplitude of the echo signal from the defect or the amplitude of the back-wall signal (when controlled by the direct transducer) is equal to the specified fixation level
Conditional defect length	The maximum distance (in a given direction) between two points located on the conditional boundary of the defect.
	Note. Designated, mm. The conditional length of the control reflector, equivalent in amplitude to this defect, is denoted , mm.
	It is allowed to define the value as a conditional length of the control reflector that determines the rejection level
Extended defect	A defect that satisfies the condition >.
Non-extended defect	A defect that satisfies the condition .
Scan speed	The speed of movement of the transducer along a given trajectory along the input surface.
Scan step	Distance between adjacent transducer paths, e.g. between rows in progressive scanning or between helical turns in helical scanning
ARD diagram	A system of graphs relating the amplitude of the echo signal with the distance to the defect and its equivalent area

The text of the document is verified by:
official publication
M.: Publishing house of standards, 1993

The control of forgings is an integral part of the stamping process and includes checking the dimensions and shape of the elements and their mechanical strength.

When measuring the dimensions of forgings, it is necessary to observe the rule of unity of the base. The basis for measuring the forging is the points on its surface, which fix the forging in the cutting fixtures. To check the dimensions of forgings, universal (calipers, calipers, indicators, etc.) and special (staples, templates, etc.) measuring tools, as well as control devices, are used. The latter are the best means for quick measurements of forgings, as they allow up to 1500 measurements per hour with an accuracy of 0.1n-0.2 mm.

Control of the mechanical strength of forgings includes chemical and metallographic analyses, mechanical, magnetic and other special tests of forgings, as well as detection of external and internal defects.

Control of the chemical composition of steel produced during the acceptance of the metal supplied to the plant, the delivery of critical forgings, the study of the causes of marriage, as well as the sorting of mixed metal, billets or forgings from steels of different grades. Chemical analysis(conducted in the laboratory) allows you to determine the percentage of any element in steel with the greatest accuracy. To do this, chips are taken from the tested rod, semi-finished product or finished forging, which is associated with a large investment of time, and often damage. finished product. That's why chemical analysis carried out only selectively. If continuous control is required, the following non-destructive methods are used.

sparkling and spectral analyzes metals make it possible to determine the compliance or non-compliance of the chemical composition of steel with a given grade with sufficient productivity and accuracy without damaging the material or forging. With spark control, with the help of a portable drill, a plentiful beam of sparks is caused from the cleaned surface of the forgings, the workpiece, or the test rod. According to the external shape and color of the sparks, an experienced inspector can distinguish the carbon content with an accuracy of 0.05% and check 600-1000 pieces of medium and small mass in one hour. The method makes it possible to fairly accurately distinguish steel grades with different carbon content or to distinguish structural steels carburized from improved ones and the latter from tool steels, as well as to distinguish some steel grades with a high content of alloying elements.

Spectral analysis is based on the decomposition and study of the spectrum of an electric arc or spark excited between the tested metal (forging) and the arrester. The brightness of the characteristic lines in the spectrum determines the quantitative content of each element in the steel. Along with portable and stationary steeloscopes used in workshop conditions, devices with microprocessors are used for analysis for automatic processing of analysis data and the issuance of ready-made information.

Eddy current method allows, on the basis of comparison with reference samples, to determine clearly and with high sensitivity not only the grade of the alloy, but also its hardness, the presence of cracks or internal stresses, the structural state, etc.

thermoelectric method based on the thermocouple principle, i.e. the occurrence of an electromotive force of various magnitudes upon contact of a heated probe with the tested metal. According to the magnitude and sign of the deviation of the galvanometer needle, calibrated according to reference samples, the steel grade is determined. The most reliable results are obtained when determining steel grades ZOHGS, 18KhGM, 40X, as well as when separating carbon steels from doped. Metal can be checked on the cleaned ends of bars or parts in racks without unloading.

Monitoring the implementation of measures that ensure the manufacture of forgings from steel of specified grades includes the following:

verification of invoices, certificates or passports for blanks received by the workshop; metal without accompanying documents is not allowed for production;
installation in the stamps of an insertable conditional brand that distinguishes this forging or steel grade from others used for this part;
verification and sorting of forgings with different brands received for acceptance or for cutting into homogeneous batches;
Brinell hardness control after heat treatment, which allows you to establish the mixing of steel grades by significant deviations in hardness and sort forgings on a statoscope or by the spark method.

Quality control of heat treatment of forgings includes two stages: control of the implementation of heat treatment modes and quality control of forgings after it.

To perform the first stage, thermal furnaces are equipped with pyrometers (thermocouples) with recorders, temperature controllers, programmable pallet pushing mechanisms. In hardening furnaces, in addition, periodically measure and record the temperature of the coolant. To register the operating mode of the furnaces and the products passing through them, a log of the established form is constantly kept for each furnace.

The second stage is carried out by the following methods:

Brinell hardness test during heat treatment as mandatory control operation with fixing the results in a journal and a control chart of statistical control, which is performed selectively;
final hardness control (solid or selective, depending on the material of the forgings and the complexity of their cutting) to ensure the normal machinability of the forgings cutting tool;
metallographic control of forgings in the laboratory, for which two forgings with extreme hardness values within the established norm are selected from each batch from among the first ones tested for hardness, from which sections are cut out for examination under a microscope;
mechanical tests in the laboratory, which are carried out regularly for the most critical forgings, when required by the technical specifications. The remaining forgings are tested only for special tasks, selecting two forgings with extreme hardness values from the batch.

Identification of external defects most often, they are performed by visual inspection of forgings directly at the forging unit - to reject obvious defects and after cleaning the scale, i.e. at the final control for the rejection of latent defects. To detect external and internal defects of critical forgings, magnetic flaw detection is also used, based on the property of the flow of magnetic field lines to change its direction when it encounters defects and delineate their boundaries.

Luminescent method detection of external defects is based on the ability of mineral oils that have penetrated into cracks to emit light under the action of ultraviolet rays. The method makes it possible to detect deep, invisible surface cracks with a width of less than 0.005 mm, which is why it is more productive and reliable than the magnetic method. This method can also be used for non-magnetic materials.

Depth of external defects is determined by local undercutting with a grinding wheel of a defect in two or three places in the transverse direction or by cutting out defects with a chisel on large forgings along the defect line until the chip being removed ceases to fork on the defect line. The depth of the undercut or cutting should not exceed half the allowance per side.

Identification of internal hidden defects and metal contamination are produced by metallographic studies in accordance with the relevant state standards and specifications. In the workshops, internal metal defects are detected using a technological sample - precipitation of samples heated to the final temperature, the height of which is equal to twice the diameter. Several samples are cut from each batch of metal (at least two from each heat) and upset to one third of the initial height. In this case, there should be no discontinuities in the upset samples.

Identification of internal defects of forgings by ultrasonic method based on the reflection of an ultrasonic beam from the surface of internal defects. The sections of the forging subjected to control must be of the same cross section. Methods of ultrasonic flaw detection make it possible to detect cavities, friability, cracks, flocks, delaminations and other discontinuities in the thickness of the metal that are not detected or are not always detected by other non-destructive testing methods. Modern installations for automated control provide for automatic scanning, registration of echo signals from defects and monitoring the quality of the acoustic contact of the sounding transducer and the surface of forgings.

Fluoroscopy For quality control of stamped forgings, they are used to a limited extent.

In today's large-scale and mass production, the pace of forging is so high that it is almost impossible to carry out a complete control of each forging. In this regard, the so-called statistical method of forging control, which is a systematic study of their quality, is increasingly being used in forging shops for forging; the results of the study are processed by methods of mathematical statistics. Statistical control is carried out during production process by small control samples at various intervals and by selective acceptance of products. Statistical analysis of products makes it possible to distinguish random causes of forging defects from regular ones and to identify its main causes.

The advantage of this method is the ability to control large quantities of forgings based on the measurement results of small batches selected in accordance with certain rules.

? CONTROL QUESTIONS AND TASKS
1. List the groups of factors that affect the quality of stamped forgings.
2. Name the types of marriage caused by the quality of the raw material of the workpiece.
3. What types of marriage caused by improper heating of workpieces are considered unrecoverable?
4. List the causes and give examples of the formation of clips during stamping.
5. What type of stamping is characterized by a defect called a press weight?
6. What types of rejects can occur if forgings are not properly cleaned from scale?
7. List the quality control methods for stamped forgings.
8. What methods are used to detect external defects in forgings?
9. How are internal defects of stamped forgings detected?
10. What is the statistical method of forging control?

The Non-Destructive Testing Laboratory of Trade House "Spetssplav" is pleased to offer you our services for ultrasonic testing of the quality of forgings and rolled metal products.

The ultrasonic method is based on the ability of ultrasonic vibrations to be reflected from the surfaces of internal defects of the metal.
With the help of ultrasound, shells, cracks, strata, fistulas and ripples are detected, which lie at a depth, in the thickness of the metal, which are not detected by magnetic and luminescent methods and are not always detected by X-rays. Having reached the opposite face of the product (to the “bottom”), the ultrasonic beam is reflected, hits a special seeker, which converts it into an alternating voltage supplied to the amplifier input, and then to the oscilloscope tube crane in the form of a peak (bottom signal). If there is a defect in the thickness of the metal, the beam is also reflected from it, and a defective signal will appear on the side of the bottom signal (the location of the defective and bottom signals on the screen is predetermined by the device of the oscilloscope).

Our laboratory is equipped with the most modern equipment, which allows you to work with various steel grades and detect hidden defects of any size. In addition, our staff consists of certified specialists who have undergone specialized training and have a confirmed qualification from Rostekhnadzor. Thanks to this, we can carry out high-quality ultrasonic testing of forgings in accordance with all requirements of the customer's technical documentation.

Some manufacturers, in order to save money or incompetence, ignore non-destructive testing of products or remember about it only at the last stage - just before the delivery of products (and this leads to additional loss of time and unforeseen costs, sometimes very significant), when the control is technically unfeasible. Such an attitude to quality control most often leads to emergency situations during the operation of finished products.

General information. The quality of the machine depends on the quality of its components and parts. Most critical machine parts are made from forgings, so the task of a forging shop or site is not only to produce a certain number of forgings, but also to ensure their high quality. This task can be solved only with the successful organization technical control in the workshop, on the site and at the workplace.

Product quality control consists in checking the compliance of quality indicators with the requirements established by State standards(GOSTs), specifications (TU) and other documents.

Important criteria for high quality are such technological features of the latter as the absence of unacceptable defects in the source material, as well as the correspondence of mechanical properties, metal structure, geometric dimensions and surface roughness of parts to the values required by technical documentation.

Organization of technical control at the enterprise and its types. Product quality control at the factory carry out two departments - technical control and state control. Products manufactured by the plant can be sent to customers only after they have been accepted by representatives of the state control department.

The difference between the technical control department (OTC) of the plant and the state control department is as follows. The quality control department, being one of the divisions of the enterprise, not only controls the quality of products, but also finds out the causes of defects and actively influences the plant's services in order to prevent them at all stages of production of parts, assemblies and machines as a whole. The department of state control, representing the interests of the customer, checks, as a rule, the quality of the final product (tractor, car, TV, etc.); it is a special division of the State Standard of the USSR at the enterprise and is not subordinate to the management of the latter.

The organizational structure of the QCD at the enterprise depends on the nature of production, the volume and type of products. At most enterprises, the quality control department includes the following subdivisions: an incoming control group that controls and accepts metal, castings, forgings, components, etc. coming to the plant from other enterprises;

central factory measuring laboratory, which, together with workshop laboratories, monitors the condition and correct use of control and measuring tools, instruments, fixtures; marriage accounting and analysis group;

bureau of technical control (BKT), which performs control of products in the workshops of the plant.

The listed divisions are subordinate to the plant's OJ; Their staff includes senior inspectors, control foremen and inspectors.

The technical control service in the forging and stamping shop has the following tasks:

prevention of the appearance of mass defects, which is achieved by timely detection of deviations from technological and specifications and withdrawal from production of worn-out dies, faulty tools, control devices and etc.;

detection of defective forgings, their removal from the bulk of suitable forgings, execution of relevant documentation indicating suitable and defective forgings and specific culprits of the marriage;

control over compliance with the established allowances, quality control of heat treatment, surface quality, etc.;

systematic registration of marriage, analysis of the reasons for its occurrence, carried out on the basis of long-term data collection in the workshop and from the consumer.

Quality Control Service provides round-the-clock control of forging production at the main operations, which include: cutting the original metal into cut-to-length blanks, heating, forging or stamping, heat treatment, finishing operations, final acceptance of forgings.

The effectiveness of technical control depends on the correct choice of its type. Depending on the contractor, technical control by the QCD employees and control by the workers themselves (self-control) are distinguished. Self-control, for example, during forging consists in checking the quality of the manufactured forging by the blacksmith himself. Those workers who are entrusted with self-control have a personal stigma of quality.

The technological process of manufacturing complex forgings can consist of a large number operations. In this case, in order to prevent the occurrence of a final marriage, technical control is carried out in stages. Preliminary control carried out in order to check the quality of the source material to prevent its processing in case of defects. Interim interoperational control is performed most often QCD controller, but sometimes by shop staff. For example, the rejection of forgings with obvious defects can be performed by the workers themselves. The final control is an obligatory operation during the delivery of finished products from workshop to workshop or to the consumer. Accepted or rejected products are branded with the appropriate stamps and the necessary documentation is drawn up for it.

Depending on the type of production and its nature (mass, serial, experimental, etc.), various means of control are used - mechanized and automated. In a single production, for example, at the forging site, parts are most often manufactured on universal equipment with a universal tool without the use of special equipment. Under the conditions of such production, manual control is used, which is performed by universal methods using a universal control and measuring tool. Equipping a single production unit with special control devices is not economically feasible; moreover, the qualifications of inspectors must be high.

Continuous improvement of the organization of control leads to the emergence of its new forms. One of them is the system of defect-free manufacturing of products and their delivery to the control service from the first presentation. With a defect-free system, not only the quality of products is controlled, but also the quality of work of workers, their qualifications, and working conditions. This system makes it possible to develop a set of organizational, technical and educational measures that ensure the defect-free operation of all production units. A defect-free labor system can be implemented at any enterprise and any production site.

In the manufacture of forgings by manual forging, the most important types of technical control are intermediate and final.

Technical control in forging production. In general, the following types of control of forgings (blanks, parts) are used to detect and prevent defects in forging production: external inspection; control of geometric dimensions; chemical composition control; control using non-destructive physical methods; metallographic analysis; mechanical tests. The listed types of control can be used both as intermediate and as final.

External examination(visual inspection) is most often used as an intermediate inspection, carried out at a hammer, press or anvil to reject forgings with obvious defects. After smoothing and descaling, an external inspection is carried out as a final control to detect surface defects visible to the naked eye. Descaling is carried out either in tumbling drums or with shot in shot blasting plants. Sand blowing is used extremely rarely and only for cleaning forgings made of expensive alloys, such as titanium. Smaller and so-called hidden defects are detected by subjecting the forgings to etching and examining them with a magnifying glass.

An external inspection also determines such types of defects as warpage, unacceptable burrs, as well as defects caused by incompletely performed operations for piercing holes, trimming flash, etc.

Control of the geometric dimensions of forgings produced by universal and special tools. Forgings obtained by hand forging are most often controlled with a universal tool - a vernier caliper, a caliper and an inside gauge with a sector scale. In the manufacture of a large series of forgings, it is more economical and more convenient to use a special control tool - staples, templates and other control devices.

The geometric dimensions of complex and large forgings made of expensive alloys are controlled on marking plates using a thickness gauge and a marking ruler, and for increased measurement accuracy, a height gauge is used (Fig. 9.5). Marking on the plate is a painstaking and time-consuming operation, but it is more economical to determine the suitability of a forging for machining in advance than to get scrap after numerous and expensive finishing operations.

When controlling geometric dimensions, it is necessary that such points of the forging surface serve as the basis for measurement, which will later be used as bases for fixing the forging on the machine when it is machining. This condition is called the "base unity rule".

The height, width, length, and diameter of the forging are measured with a ruler, a caliper, a regular caliper, or a caliper with a sector scale. The choice of measuring tool depends on the overall dimensions of the forging and the required measurement accuracy. The control of the indicated dimensions is carried out with limit brackets, bar templates and combs. To measure the wall thickness of forgings, calipers with a sector scale are used (see Fig. 5.12, b), calipers, and to control the suitability of a part, limit brackets and limit calipers are used.

Hole diameters are measured with calipers and bore gauges. The suitability of forgings is determined by holes using limit gauges and templates. Control of forgings for bending (curvature) and warpage of surfaces is carried out on the plate by measuring the distance from the control surfaces of the forging to the surface of the plate. The warping of a round forging is determined by rolling it over the slab and measuring the deflection. Warping control is performed using profile templates.

Angular dimensions are determined by universal goniometers, bevels and control templates. Curve radii between adjacent surfaces of the forging are checked with a set of universal radius templates (from 1 to 15 mm), as well as limit templates for measuring the outer and inner radii of roundings. The correctness of the relative position of the protrusions and depressions on the forging is determined either on the plate, or using a height gage, or profile and contour templates.

Forgings with dimensional deviations exceeding the allowable ones are defective. Those that can be corrected by additional forging are sent for elimination of defects, the rest are rejected.

Control of the chemical composition of the metal of blanks and forgings in performed due to the fact that chemical composition affects not only the performance of parts, but also the mode of their processing. Therefore, the non-compliance of the chemical composition of the workpiece metal with the established requirements, as well as the erroneous choice of the alloy brand, are unacceptable. The control of the chemical composition of the alloy is carried out upon acceptance of metal arriving at the plant, upon acceptance of forgings for the most critical parts, when investigating the causes of defects, and also in the case when blanks of the same size prepared for forging were moved or there was no stamp or tag on them.

In forging production, chemical analysis in the laboratory and spectral analysis are widely used to determine the chemical composition of the metal, and the spark method is used to determine the grade of the alloy.

For chemical analysis, the used blanks or forgings are selected a certain amount of shavings or small pieces of metal and sent to the laboratory, where methods quantitative analysis the chemical composition of the alloy is determined with high accuracy. The accuracy of determining the presence of sulfur and phosphorus, for example, reaches 0.004. . . 0.005%, tungsten and nickel - 0.04. . . 0.06%, other elements - 0.02. . . 0.04%. The disadvantages of chemical analysis include the long duration and complexity of its implementation. So, to determine the amount of carbon, 5 minutes are required, sulfur or phosphorus - 1 hour, aluminum - 2 hours, and titanium - 3 ... 4 hours. As a result, chemical analysis is used in random control, rejection analysis, accurate rechecking (for example, in case of premature failure of a part during operation).

Compared with chemical spectral analysis, it is more convenient, economical and fast. This method is less accurate than chemical analysis, but allows one grade of alloy to be separated from another with a reasonable approximation, and the control is carried out very quickly and without damage to the finished forging. The accuracy of determining the elements reaches ... 1%, and the time spent is from 1 to 3 minutes per analysis.

Spectral analysis is based on the decomposition and study of the spectrum of an electric arc or spark artificially excited between a copper electrode and the alloy under study. To perform spectral analysis, a stationary or the most convenient portable steeloscope in production conditions is used (Fig. 9.6). An electric arc occurs between the tested sample 6 and disk electrode 5. The beam of light from the soul through prisms 7, 11 and 12, lenses 8, 10 and 2, as well as refractive prisms 3 and 4 enters eyepiece 1, through which the spectrum is observed and analyzed. The color and concentration of the lines of the latter allow using the atlas attached to the device to determine the presence of the element and its approximate percentage in the alloy. Steeloscope weighing 3 kg is easy to carry by the handle 9; its performance reaches 60 . . . 100 tests per hour. The steeloscope makes it possible to carry out control analyzes of both small and large forgings, as well as to control parts directly on machines without disassembling them.

An effective way to determine the grade of an alloy is the spark method. When using it, the grade of the alloy is established visually by the type of sparks generated during the abrasive treatment of the forging with a grinding wheel or drill (see Fig. 3.4). Despite the fact that this method is very approximate, experienced inspectors determine the alloy grade of 600 ... 1000 samples within 1 hour.