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1、 USSR STATE STANDARD STEELS AND ALLOYS METHODS OF DETECTION AND DETERMINATION OF GRAIN SIZE GOST 5639-82 Official Edition English Version Approved by Interstandard STANDARDS PUBLISHING HOUSE Moscow Copyright Gosudarstvennye Standarty State Standard GOST (Russian) Provided by IHS under license with G
2、OST pLicensee=IHS Employees/1111111001, User=Japan, IHS Not for Resale, 08/11/2008 20:10:33 MDTNo reproduction or networking permitted without license from IHS -,-,- 5639-82 1 UDC 669.01.538.215.2:006.354 Group B09 USSR STATE STANDARD STEELS AND ALLOYS Methods of detection and determination of grain
3、 size OKSTU (All-Union Classification Code of Standards and Specifications) 0909 GOST 5639-82 Date of introduction 01.01.83 This Standard establishes metallographic methods of detection and determination of steels and alloys grain size. The following characteristics shall be determined by metallogra
4、phic methods: the real grain size (after hot deformation or any heat treatment); tendency of a grain to growth by determination of austenite grain size after heating at a temperature and a hold period both established by specifications and technical documentation for steels and alloys. kinetics of g
5、rain growth by determination of a grain size after heating at a temperature range and a hold period both established by specifications and technical documentation for steels and alloys. 1. SAMPLING 1.1. The sampling place and a number of samples for the grain size determination shall be established
6、by specifications and technical documentation on steels and alloys. 1.1.1. For lack of instructions the sampling for the real grain determination shall be carried out arbitrarily; for determination of tendency of a grain to growth and growth kinetics the sampling shall be carried out in the sampling
7、 place for mechanical test. Official Edition Reprinting is prohibited * Standards Publishing House, 1982 Standards Publishing House, 1994 Revised Edition with Amendments Copyright Gosudarstvennye Standarty State Standard GOST (Russian) Provided by IHS under license with GOST pLicensee=IHS Employees/
8、1111111001, User=Japan, IHS Not for Resale, 08/11/2008 20:10:33 MDTNo reproduction or networking permitted without license from IHS -,-,- 5639-82 2 1.1.2. For lack of instructions in specifications and technical documentation the test for one sample shall be performed. 1.2. The sectional area of a s
9、ample microsection shall be of no less than 1 cm2. It is allowed to make microsections with the area of less than 1 cm2 for the metal products of less than 8 mm thick. For determination of tendency of a grain to growth and kinetics of grain growth the forged ladle sampling is allowed, provided that
10、test results are comparable with the results of the finished metal products. 2. METHODS OF GRAIN BOUNDARIES DETECTION 2.1. Grain boundaries shall be detected by the following methods: etching, cementation, oxidation, ferrite or cementite grid , pearlite grid (troostite), vacuum thermal etching. The
11、method shall be chosen depending on chemical composition of steel and the test objective. 2.1.1. E tching method 2.1.1.1. The etching method shall be applied for detection of the real grain boundaries as well as the austenite grain boundaries in carbon and alloy steels, hardened for martensite or ba
12、inite, and in steels in which it is difficult to obtain ferrite or cementite grid. 2.1.1.2. The real grain boundaries detection shall be carried out for the samples without additional heat treatment. 2.1.1.3. For austenite grain boundaries detection the heat temperature, hold period and cooling rate
13、 shall be established by specifications and technical documentation for steels and alloys. In case the heat temperature and the hold period are not established by specifications and technical documentation, the temperature for low-carbon steels shall be 930 ( 10). For other steels the heat temperatu
14、re shall be equal or 20 to 30 higher than the hardening temperature established by specifications and technical documentation. The hold period shall be of no less than 1 hour and no more than 3 hours. For more legible detection of real and austenite grain boundaries the samples shall be subject to t
15、empering: for carbon and low-alloy steel at 225 to 250 , for alloy steels and alloys at 500 C and higher depending on chemical composition. Copyright Gosudarstvennye Standarty State Standard GOST (Russian) Provided by IHS under license with GOST pLicensee=IHS Employees/1111111001, User=Japan, IHS No
16、t for Resale, 08/11/2008 20:10:33 MDTNo reproduction or networking permitted without license from IHS -,-,- 5639-82 3 2.1.1.4. Decarbonized layer shall be removed from the surface of a sample, a microsection shall be manufactured and then etched in the reagents, specified in Appendix 1 or others, al
17、lowing legibly to detect the grain boundaries. The universal reagent for steel etching is a newly-prepared water solution of picric acid saturated at a room temperature with the addition of 1 to 10 % of surface-active substances such as Syntonol or washing detergents such as “Progress”, “Aster”, sha
18、mpoo “Lada” or other alkylsulfonate compounds. For more legible detection of grain boundaries the rebuffings shall be carried out with the after-etching and the reagent heating up to 50 to 70 . 2.1.2. Cementation method 2.1.2.1. The cementation method shall be applied for detection of austenite grai
19、ns in steels, designed for cementation, and for carbon non-cemented steels with the carbon mass fraction of up to 0.25 %. The grain boundaries shall be detected in the cemented layer as a grid of secondary cementite. 2.1.2.2. The samples without traces of oxidation and decarbonization shall be heate
20、d at a temperature of 930 (10) in a tightly closed box filled with fresh carbonizer of one of the following compositions: 60 % of charcoal and 40 % of barium carbonate; 70 % of charcoal and 30 % of sodium carbonate; 100 % of ready bondyuzhinsky carbonizer; 100 % of semi-coke carbonizer in accordance
21、 with GOST 5535-76. The box size shall be chosen depending on a number of samples, the distance between which in a box shall be of no less than 20 mm. The volume of the carbonizer shall be 30 times as much as the samples volume. The hold period after the box heating shall be of 8 hours. The samples
22、after the cementation shall be cooled together with the box to 600 with the various rates: the carbon steel for no more than 150 per one hour and the alloy steel for no more than 50 per one hour. The samples cooling rate of lower than 600 per one hour is not regulated. 2.1.2.3. After cementation the
23、 samples shall be bisected, or a surface layer of 2 to 3 mm deep shall be removed from one side, and the microsections shall be manufactured. Copyright Gosudarstvennye Standarty State Standard GOST (Russian) Provided by IHS under license with GOST pLicensee=IHS Employees/1111111001, User=Japan, IHS
24、Not for Resale, 08/11/2008 20:10:33 MDTNo reproduction or networking permitted without license from IHS -,-,- 5639-82 4 For cementite grid detection the microsections are recommended to be etched in one of the following reagents: 3 to 5 % solution of nitric acid in ethyl alcohol; 5 % solution of pic
25、ric acid in ethyl alcohol; sodium picrate solution, consisting of 2 g of picric acid, 25 g of caustic soda (hydrate of sodium) and 100 cm3 of water (electrolytic etching, the cell terminal voltage shall be of 6 to 10 V, the etching time shall be a few seconds); boiling solution of sodium picrate (ch
26、emical etching, the etching time shall be 10 to 20 minutes). 2.1.3. O xidation method 2.1.3.1. The oxidation method is applied for structural and tool (carbon and alloy) steels. Austenite grain boundaries shall be detected by a grid of oxides. 2.1.3.2. The samples with the buffed surface shall be su
27、bject to heating up to a definite temperature and held for a period of time in accordance with Clause 2.1.1.3. Heating shall be carried out in vacuum or in a protective atmosphere. For oxidation of microsections after holding period, the air shall be fed into a furnace for 30 to 60 second without th
28、e temperature lowering. The grey iron chips, charcoal powder, water solution of sodium tetraborate and others may be applied for oxidation protection during microsections heating, provided that the obtained grain size results correspond to those obtained by the etching method. (Amended Wording, Amen
29、dment No. 1). 2.1.3.3. After cooling in water and buffing the sample shall be etched in one of the reagents of the following compositions: 15 cm3 of hydrochloric acid and 75 cm3 of ethyl alcohol; 1 g of picric acid, 5 cm3 of hydrochloric acid and 100 cm3 of ethyl alcohol; 5 cm3 of metanitrobenzenesu
30、lfacid and 10 cm3 of ethyl alcohol. (Amended Wording, Amendment No. 1). 2.1.3.4. Before cooling in water the microsection may be processed in the fused water solution of sodium tetraborate (heated up to the austenization temperature) for 30 to 40 seconds. After the processing in water solution of so
31、dium tetraborate the grain boundaries are detected without the additional etching. 2.1.4. Ferrite or cementite grid method 2.1.4.1. Ferrite or cementite grid method is applied for grain boundaries detection in hypoeutectoid (with the carbon mass fraction of up to 0.6 %) and hypereutectoid steels cor
32、respondingly. 2.1.4.2. The samples with any state of surface shall be subject to heating up to the definite temperature and held for the period of time in accordance with Clause 2.1.1.3. Copyright Gosudarstvennye Standarty State Standard GOST (Russian) Provided by IHS under license with GOST pLicens
33、ee=IHS Employees/1111111001, User=Japan, IHS Not for Resale, 08/11/2008 20:10:33 MDTNo reproduction or networking permitted without license from IHS -,-,- 5639-82 5 For ferrite or cementite grid formation along the grain boundaries the samples shall be cooled to a temperature of 650 with the differe
34、nt rates depending on the steel grade. For carbon steels with the carbon mass fraction of 0.5 to 0.6 % the cooling rate shall be of 50 to 100 per hour, for alloy and carbon hypereutectoid steels of 20 to 30C per hour, the steels with the carbon mass fraction of 0.25 to 0.5 % shall be cooled by the a
35、ir. 2.1.4.3. After the heat treatment the sample shall be bisected, or a surface layer (decarbonized) shall be removed by grinding, and then it shall be buffed and etched. An austenite grain by a ferrite grid shall be detected by etching in 4 % solution of nitric acid in ethyl alcohol, and by a ceme
36、ntite grid it shall be detected by etching in the reagents specified in lause 2.1.2.3. 2.1.5. Pearlite (troostite) grid method 2.1.5.1. The method of grain boundaries detection by a pearlite (troostite) grid is applied for carbon and low-alloy steels, similar by their composition to eutectoid ones.
37、The grain boundaries shall be detected by dark-etching pearlite grid in transition zone of a sample. 2.1.5.2. The samples with any state of surface shall be subjected to heating at a definite temperature and held for the period of time in accordance with Clause 2.1.1.3. For the pearlite grid formati
38、on the samples shall be cooled by immersing half of a sample into the water while the other half is cooled by the air. 2.15.3. After the heat treatment, the sample plane perpendicular to the transition zone at a height of water level, shall be grinded up to the decarbonized layer removal and then bu
39、ffed and etched in the reagents (3 to 5 % solution of nitric acid in ethyl alcohol or 5 % solution of picric acid in ethyl alcohol) 2.1.6. Vacuum thermal etching method 2.1.6.1. The method of thermal etching in vacuum with the use of high-temperature microscopes is recommended for determination of k
40、inetics of austenite grain growth. The method is based on selective evaporation of metal along the grain boundaries at high temperatures. 2.1.6.2. The samples of definite shape and dimensions (depending on installation type) with the buffed surface shall be placed in a high-temperature chamber, wher
41、e vacuum of 0.0133 to 0.00133 Pa (10-4 to 10-5 mm of mercury) shall be pumped, and then heated up to a definite temperature. To suppress the evaporation of metal from the microsection surface at high temperatures (higher than 900 ), an inert gas (argon at overpressure of 0.03 to 0.05 MPa 0.3 to 0.5
42、atmospheres), prepurified of oxygen and moisture, shall be fed in the chamber. Copyright Gosudarstvennye Standarty State Standard GOST (Russian) Provided by IHS under license with GOST pLicensee=IHS Employees/1111111001, User=Japan, IHS Not for Resale, 08/11/2008 20:10:33 MDTNo reproduction or netwo
43、rking permitted without license from IHS -,-,- 5639-82 6 For austenite grain detection in steels with the increased content of oxidable elements (1, r, etc.) the use of protective shields is recommended, such as the metal getters having large affinity with oxygen (Ta, Ti, Cd, Zr, etc.). 2.1.6.3. The
44、 hold period shall be of no less than 20 minutes, the heating temperature shall be not lower than 800 . 2.1.6.4. The grain size evaluation shall be carried out with aid of a microscope or microphotos. 3. METHODS OF GRAIN SIZE DETERMINATION 3.1. Grains of metals represent the separate crystals of pol
45、ycrystalline conglomerate, partitioned by the adjacent surfaces, named the grain boundaries. Grains may be equiaxed and unequiaxed. If there are twinned crystals, the crystal twins shall be considered as grains. 3.2. The grain size is an average of random sections of grains in a plane of metallograp
46、hic microsection and shall be determined by the following methods: visual comparison of grains, visible by microscope, with the scale standards specified in the obligatory Appendix 2, with grain number determination; calculation of grains quantity per microsection unit area, with the average diamete
47、r and average grain area determination; calculation of grain boundaries crossings with the line segments, with determination of average conditional diameter in case of equiaxed grains and of grains quantity in 1 mm3 in case of unequiaxed grains; measurement of chord lengths with the use of microscop
48、e or microphotos with the determination of relative proportion of grains with definite dimensions; ultrasonic. The specified methods are applied for evaluation of a grain size having a shape, close to the equiaxed one. The method of calculation of grain boundaries crossings is applied for size evaluation of oblong-shaped grain. In case of grain size determination in different-grained structure, the average dimensions (diameter, grain area) shall not se