| 摘要 |
<p>METHOD AND APPARATUS FOR CASE HARDENING POWDERED METAL PARTS A method and apparatus is provided for case hardening a porous, powdered metal part by means of a gaseous atmosphere without incurring excessive embrittlement or unacceptable physical distortion of the part. Prior to subjecting the part to the case hardening gaseous atmosphere, the part is heated in an oxidizing atmosphere for a time period sufficient to form oxides of iron which substantially fill the pores at the surface of the part. When the part is later subjected to the case hardening gaseous atmosphere, at least one element of the gaseous atmosphere reacts with the oxides of iron and Fe to produce hardenable iron compounds.</p> |
