SAE J442:2020 pdf free

SAE J442:2020 pdf free.Test Strip, Holder, and Gage for Shot Peening
All strips shall be uniformly hardened and tempered to produce tempered martensite having a hardness, as measured on the surface, of HRC (44 to 50) for the A and C strips, and HRA (72.5 to 76.0) for the N strips. Hardness shall be measured in accordance with ASTM E18 at approximately 13 mm (or 0.50 inch) from either end of the strip on the longitudinal center line of a flat side. Sampling for hardness testing of the strips shall be used. Hardness for sub-size test strips shall be measured in accordance with ASTM E18 at approximately 6.5 mm (or 0.25 inch) from either end of the strip on the longitudinal center line of a flat side. Hardness determination precludes other use of the strip.
Strips shall be free from alteration of surface carbon level to the degree that any difference in average hardness between the surface and subsurface material shall not exceed two points as measured on the Rockwell 30-N scale. The average of at least four readings in each should be used to make the comparison. Any such determination must be made on strips which have not been shot peened; hardness determination will preclude other use of the strip. Surface hardness readings that are less than subsurface readings indicate evidence of decarburization. Surface readings which are higher than the corresponding subsurface values indicate carburization. For example: If the average surface hardness is 62.5 on the Rockwell 30-N scale and, after careful grinding, a region below the surface is found to be 64.0 on the Rockwell 30-N scale, the strip is acceptable. If the subsurface reading had been 65.0 on the Rockwell 30-N scale, the difference (2.5 points) being over two points would constitute grounds for rejection.
Sub-size test strips shall be attached using adhesive material, such as contact cement or double-sided tape, across the entire length of the sub-size test strip, or by screw heads at either end of the length of the sub-size test strip. The method of attachment shall be held consistent for the development of the correlation chart between sub-size intensity and true intensity, as well as for testing saturation curve development using sub-size test strips in the area of question.SAE J442 pdf free download.