Grade B7M—The maximum hardness of the grade shall be 235 HBW or 99 HRB. The minimum hardness shall not be less than 200 HBW or 93 HRB. Conformance to this hardness shall be ensured by testing the hardness of each stud or bolt by Brinell or Rockwell B methods in accordance with 9.2.1. The use of 100 % electromagnetic testing for hardness as an alternative to 100 % indentation hardness testing is permis-sible when qualified by sampling using indentation hardness testing. Each lot tested for hardness electromagnetically shall be 100 % examined in accordance with Practice E566. Follow-ing electromagnetic testing for hardness, a random sample of a minimum of 100 pieces of each heat of steel in each lot (as defined in 12.1.1) shall be tested by indentation hardness methods. All samples must meet hardness requirements to permit acceptance of the lot. If any one sample is outside of the specified maximum or minimum hardness, the lot shall be rejected and either reprocessed and resampled or tested 100 % by indentation hardness methods.
Bolts, screws, studs, and stud bolts shall be pointed and shall have a workmanlike finish. Points shall be flat and chamfered or rounded at option of the manufacturer. Length of point on studs and stud bolts shall be not less than one nor more than two complete threads as measured from the extreme end parallel to the axis. Length of studs and stud bolts shall be measured from first thread to first thread.
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