Heat Treatment Atmosphere Effects on Surface Characteristics and Properties of Various Commercial Alloys. Final Report January 1987-February 1988

摘要

The objective of the work is to determine the levels to which impurities such as O2 and H2O in furnace atmospheres must be reduced to avoid surface and internal oxidation of commercial alloys during heat treatment in gas atmospheres at atmospheric and subatmospheric pressures. The commercial alloys selected for examination were heat treated individually in a variety of gas atmospheres including: dried and purified N2 at one atmosphere (760 torr) and at 200, 100, and 10 torr; and mixtures of N2 and H2 at 760 torr and at 100 torr. The combination of an addition of H2 to N2 and a reduction of the system pressure to 100 to 200 torr (dynamic soft vacuum) produced the highest quality surface appearance in the alloys and eliminated to all traces of subsurface damage (internal oxidation and nitriding), and is, therefore, the recommended procedure for commercial heat treating in gas atmospheres.