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/J1993_201310 SURFACE VEHICLE RECOMMENDED PRACTICE J1993 OCT2013 Issued 1993-03 Re
5、affirmed 2013-10 Superseding J1993 JUL2005 High-Carbon Cast-Steel Grit RATIONALE J1993 has been reaffirmed to comply with the SAE five year review policy. 1. ScopeThis SAE Recommended Practice describes the chemical composition, and physical characteristicrequirements for high-carbon cast-steel grit
6、, to be used for blast cleaning and etching operations.1.1 RationaleThis document has been reaffirmed to comply with the SAE 5-Year Review policy.2. References2.1 Applicable PublicationsThe following publications form a part of this specification to the extent specifiedherein. Unless otherwise indic
7、ated, the latest issue of SAE publications shall apply.2.1.1 SAE PUBLICATIONAvailable from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001.SAE J444Cast Shot and Grit Size Specifications for Peening and CleaningSAE J445Metallic Shot and Grit Mechanical Testing2.1.2 ASTM PUBLICATIONSAvailable f
8、rom ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959.ASTM B 215Method BMethods of Sampling Finished Lots of Metal PowdersASTM E 140Hardness Conversion Tables for Metals (Relationship Between Brinell Hardness, VickersHardness, Rockwell Hardness, Rockwell Superficial Hardness, and Knoop H
9、ardness)ASTM E 384Test Methods for Microhardness of Materials2.1.3 ISO PUBLICATIONSAvailable from ANSI, 25 West 43rd Street, New York, NY 10036-8002.ISO 11124 Part 3High-carbon cast-steel shot and gritISO 11125 Part 1Preparation of steel substrates before application of paints and related productsTe
10、stmethods for metallic abrasivesPart 1: SamplingISO 11125 Part 2Preparation of steel substrates before application of paints and related productsTestmethods for metallic abrasivesPart 2: Determination of particle size distributionISO 11125 Part 3Preparation of steel substrates before application of
11、paints and related productsTestmethods for metallic abrasivesPart 3: Determination of hardnessISO 11125 Part 4Preparation of steel substrates before application of paints and related productsTestmethods for metallic abrasivesPart 4: Determination of apparent densityISO 11125 Part 5Preparation of ste
12、el substrates before application of paints and related productsTestmethods for metallic abrasivesPart 5: Determination of percentage defective particles andmicrostructureISO 11125 Part 6Preparation of steel substrates before application of paints and related productsTestmethods for metallic abrasive
13、sPart 6: Determination of foreign matterISO 11125 Part 7Preparation of steel substrates before application of paints and related productsTestmethods for metallic abrasivesPart 7: Determination of moisture3. DescriptionHigh-carbon cast-steel grit is the product obtained by crushing heat-treated high-
14、carbon cast-steel shot. The resulting angular particles are screened to a range of sizes from G10 to G325 as described inSAE J444.4. Size Classification and Hardness Identification4.1 High-carbon cast-steel grit will be identified by HCS G, followed by a number which represents the sievedesignation,
15、 in accordance with SAE J444, followed by a letter designating the grit hardness range. See theexample following 6.3 for the full grit designation.5. Chemical Compositiona. Carbon0.80 to 1.20%b. Manganese0.60 to 1.20%c. Silicon0.40% minimumd. Sulphur0.05% maximume. Phosphorus0.05% maximum6. Hardness
16、6.1 The four standard hardness ranges for high-carbon cast-steel grit are as follows:a. HCS G(1)SThe hardness range shall be 40 to 51 HRCb. HCS G(1)MThe hardness range shall be 47 to 56 HRCc. HCS G(1)LThe hardness range shall be 54 to 61 HRCd. HCS G(1)HThe hardness shall be 60 HRC minimum6.2 90% of
17、the hardness readings shall be within the specified range. For HCS G(1)H, 90% of the readings shallbe 60 HRC or higher.6.3 Special HardnessOther hardnesses may be specified by the user. The minimum hardness range that canbe specified is 7 points HRC.EXAMPLEHCS G25S indicates a high-carbon cast-steel
18、 grit meeting the G25 requirements in SAE J444,with a hardness designation of S (40 to 51 HRC).7. MicrostructureThe microstructure of high-carbon cast-steel grit shall consist of martensite, tempered to adegree consistent with the hardness, with fine, well distributed carbides, if any. Some retained
19、 austenite maybe observed in H hardness grit.8. General AppearanceThe cast-steel grit shall be as angular as commercially possible. A total of no morethan 40% of the grit particles shall have objectionable characteristics or contain more than 1% by weight ofnonmetallic material. Any one particle tes
20、ted that has more than one objectionable characteristic will only becounted once in the total. Notwithstanding the allowable percentages listed as follows, no more than a total of40% objectionable particles are allowed.1. Grit size designation from SAE J444._ SAE INTERNATIONAL J1993 Reaffirmed OCT20
21、13 Page 2 of 38.1 Objectionable Characteristics8.1.1 PARTICLE SHAPEFor the hard steel grits, HCS G(1)L, HCS G(1)H, there shall be no more than 5% round orhalf round particles. For the soft steel grits, HCS G(1)S and HCS G(1)M, there shall be no more than 10%round or half round particles.8.1.2 SHRINK
22、AGENo more than 10% of the particles in the sample shall contain shrinkage. Shrinkage is aninternal cavity with irregular dendritic surface, greater in area than 40% of the pellet area.8.1.3 CRACKSNo more than 40% of the particles examined shall contain major cracks. A major crack is definedas a lin
23、ear discontinuity whose length is greater than three times its width and is radial in direction.8.1.4 MICROSTRUCTURECarbide networks, grain boundary segregation, decarburization, and high-temperaturetransformation products such as pearlite are undesirable. No more than 15% of the particles tested sh
24、allcontain these defects.9. DensityThe density of the cast steel grit shall not be less than 7.3 g/cm3.10. Inspection Procedures10.1 SamplingSamples for testing shall be representative of each shipment or production lot. The method ofsampling shall be ASTM B 215 Method B.10.2 Sample Mounting for Tes
25、tingGrit samples used for testing for hardness, microstructure, and objectionabledefects shall be mounted one layer deep in bakelite or other suitable strong metallurgical sample mountingmedia.The mounted sample shall be ground to the center of the partical and polished using methods acceptable form
26、icroscopic examination. When grinding and polishing the sample, care must be taken not to overheat thesample and affect microstructure and/or hardness.10.3 Chemical AnalysisAny suitable ASTM analytical procedure for steel may be used to test chemicalcomposition.10.4 Hardness TestingHardness measurem
27、ents shall be taken on any sound area of a particle, preferablyhalfway between the center and the edge, on a minimum of ten particles in the mounted specimen. Thehardness shall be determined in accordance with ASTM E 384 or equivalent microhardness testing methods.For G-80 and smaller grit, a load o
28、f 100 g shall be used. For G-50 and G-40, grit a load of 500 g shall be used.For grit larger than G-40, the load may be either 500 or 1000 g. Conversion to approximate Rockwell Cnumbers may be obtained from ASTM E 140 and manufacturers of hardness testers.10.5 MicrostructureThe mounted and polished
29、specimen shall be etched with a suitable etchant and examinedat a magnification of approximately 500 diameters.10.6 Shrinkage and CracksShrinkage and cracks shall be determined using a magnification of ten diameters.10.7 DensityDensity shall be determined by placing 50 mL of water or alcohol in a 10
30、0 mL graduate, adding 100g of shot and recording the increase in volume. Dividing 100 g by the volume increase will give the density ing/cm3. A pycnometer method may be used for more critical density measurements.10.8 Mechanical TestsSee SAE J445 for methods of checking uniformity of shipments of grits.PREPARED BY THE SAE SURFACE ENHANCEMENT DIVISION OF THE SAE FATIGUE DESIGN AND EVALUATION EXECUTIVE COMMITTEE_ SAE INTERNATIONAL J1993 Reaffirmed OCT2013 Page 3 of 3
