| 摘要 |
<p>Steel grit, for use with centrifugal wheels in blasting metal surfaces, has a hardness between 35 and 64 Rockwell C and consists of a martensitic steel that has been converted by heat treatment of an austenitic steel having 1.0-1.5% C, 0.4-0.9% Si, and one or more of Mn 1.0-1.5%, Cr 0.5-5.0%, Mo 0.3-5.0%, V 0.05-0.40%, Ni 0.5-2.5%, Cu 0.2-1.0% and the remainder Fe apart from usual impurities. It is made from austenitic steel particles (shot) which are heated to 1400 DEG -1700 DEG F., quenched, then crushed into irregularly shaped fragments preferably less than 0.1 inch in major dimension, pieces in excess of this size being recycled for further fragmentation. The grit may be tempered by a further heating 850 DEG -1000 DEG F. followed by air cooling. Specification 667,016 is referred to.</p> |
