SAE J 2175-2015 Specifications for Low Carbon Cast Steel Shot.pdf

1、 SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising there

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4、0 (outside USA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE values your input. To provide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/J2175_201506 SURFACE VEHICLE RECOMMENDED PRACTICE J2175 JUN2015 Issued 1991-06 Re

5、vised 2015-06 Superseding J2175 JUN1991 Specifications for Low Carbon Cast Steel Shot RATIONALE Revise section 6 of standard (Hardness) to align it with the hardness range stated in SAE J827: High Carbon Cast Steel Shot. Range will be changed from 40 - 50 Rc to 40 - 51 Rc. 1. SCOPE This SAE Recommen

6、ded Practice describes chemical analysis, hardness, microstructure, and physical characteristic requirements for low carbon cast steel shot to be used for shot peening or blast cleaning operations. 2. REFERENCES 2.1 Applicable Documents The following publications form a part of this specification to

7、 the extent specified herein. Unless otherwise indicated, the latest issue of SAE publications shall apply. 2.1.1 SAE Publications Available from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or 724-776-4970 (outside USA), www.sae.org

8、 SAE J444 Cast Shot and Grit Size Specifications for Peening and Cleaning SAE J445 Metallic Shot and Grit Mechanical Testing SAE J2175 Revised JUN2015 Page 2 of 4 2.1.2 ASTM Publications Available from ASTM International, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA 19428-2959, Tel:

9、610-832-9585, www.astm.org ASTM A 370 Test Methods and Definitions for Mechanical Testing of Steel Products ASTM E 384 Practice for Safeguarding Against Warpage and Distortion During Hot-Dip Galvanizing of Steel Assemblies 3. DESCRIPTION Low carbon cast steel shot is the product obtained by atomizin

10、g and rapidly solidifying particles of molten steel in a controlled range of sizes. These shot particles are then screened to produce a range of sizes from LCS-70 to LCS-1320 or larger as described in SAE J444. 4. CLASSIFICATION Low carbon cast steel shot shall be identified by LCS followed by the n

11、umbers representing the nominal size in ten thousandths of inches, in accordance with SAE J444, i.e., LCS-460. 5. CHEMICAL COMPOSITION The finished low carbon steel shot shall have the following chemical composition as listed in Table 1: TABLE 1 - CHEMICAL COMPOSITION Low Carbon Steel Shot Chemical

12、Composition Carbon 0.10 to 0.15% Silicon 0.10 to 0.25% Manganese 1.20 to 1.50% Aluminum 0.05 to 0.15% Phosphorus 0.035% maximum Sulfur 0.035% maximum 6. HARDNESS The hardness of 90% of all shot particles tested shall be within the range of 400 to 540 KHN (40 to 51 Rockwell C). 7. MICROSTRUCTURE The

13、microstructure of low carbon cast steel shot shall be an intermediate structure (bainite), a mechanical mixture of ferrite and cementite particles with random feather-like appearance (upper bainite) and accicular (lower bainite) with few or no free carbides (see 8.1.5). 8. GENERAL APPEARANCE The low

14、 carbon steel shot shall be as spherical as commercially possible and no more than 20% of the shot particles shall have objectionable defects. Any one particle tested that has several different defects will only be counted once in the total. Notwithstanding the allowable percentages listed as follow

15、s, no more than a total of 20% objectionable particles are allowed. SAE J2175 Revised JUN2015 Page 3 of 4 8.1 Objectionable Defects 8.1.1 Particle Shape No more than 5% of the particles in a shot sample shall be elongated. An elongated particle is one whose length is in excess of twice the maximum p

16、article width. 8.1.2 Voids No more than 10% of the particles in a sample shall contain voids. A void is a smooth surfaced internal hole and must be greater than 10% of the particle to be considered harmful and counted as a void. 8.1.3 Shrinkage No more than 10% of the particles in a sample shall con

17、tain shrinkage. A shrinkage area is an internal cavity with an irregular dendritic surface, and must be greater than 40% of the particle area to be considered harmful. 8.1.4 Cracks No more than 5% of the particles in a shot sample shall contain cracks. A crack is a linear discontinuity whose length

18、is greater than three (3) times its width and its length is greater than 20% of the diameter or shortest dimension of the particle and radial in orientation. 8.1.5 Microstructure Carbide networks, partial decarburization, and grain boundary segregation are undesirable. No more than 15% of the partic

19、les tested shall have these defects. 8.1.6 Nonmagnetic Material No more than 1% of the shot sample, by weight, shall be nonmagnetic material. 9. DENSITY The density of low carbon cast steel shot shall be not less than 7 g/cc. 10. MECHANICAL TESTS To conform with revised SAE J445. 11. INSPECTION PROC

20、EDURES 11.1 Sampling Samples for chemical analysis, hardness, microstructure, density, objectionable defects, and mechanical testing shall be carefully obtained to be representative of each shipment of production lot. 11.2 Sample Mounting for Testing Shot samples used for testing for hardness, micro

21、structure, and objectionable defects shall be mounted one layer deep in bakelite or other suitable strong metallurgical sample mounting media. The mounted sample shall be ground to the center of the particle and polished by acceptable methods for examination using a microscope. When grinding and pol

22、ishing the sample, care must be taken not to overheat the sample and affect microstructure and/or hardness. SAE J2175 Revised JUN2015 Page 4 of 4 11.3 Hardness Testing Hardness measurements shall be taken at the half radius on a minimum of ten (10) randomly selected particles in the mounted sample.

23、The hardness shall be determined by using ASTM E 384 and using a 500 gf load for sizes LCS-280 and finer and 500 or 1000 gf load for sizes LCS-330 and larger. Other microhardness test methods may be used as long as a reliable hardness conversion can be obtained by calibrating various machines agains

24、t known standards. Approximate conversions to Rockwell C hardness numbers are obtained from ASTM A 370. 11.4 Microstructures The mounted and polished sample shall be etched with 2% Nital and examined at approximately 500X magnification. 11.5 Objectionable Defects Objectionable defects shall be measu

25、red using a microscope with a 10X magnification. All of the particles contained in the mount shall be evaluated. 11.6 Density Density shall be determined by placing 50 ml of ethanol or methanol in a 100 ml graduate, adding 100 g of shot and recording the increase in volume. Dividing 100 g by the vol

26、ume increase will give the density in grams per cubic centimeter (cc). A pycnometer method may be used for more critical density measurements. 11.7 Nonmagnetic Material A hand magnet shall be used to separate the magnetic shot from the nonmagetic contaminants. The nonmagetic contaminants shall be we

27、ighed and the percentage of the original sample weight calculated. 11.8 Chemical Analysis Any suitable ASTM analytical procedure for steel may be used to test chemical analysis. 12. NOTES 12.1 Marginal Indicia A change bar (l) located in the left margin is for the convenience of the user in locating

28、 areas where technical revisions, not editorial changes, have been made to the previous issue of this document. An (R) symbol to the left of the document title indicates a complete revision of the document, including technical revisions. Change bars and (R) are not used in original publications, nor in documents that contain editorial changes only. PREPARED BY THE SAE SURFACE ENHANCEMENT COMMITTEE