Excellent results are obtained by austenitizing water-hardening tool steels in a slightly oxidizing atmosphere, as indicated by the data in the graph, obtained in tests on type W2. The graph shows the effect of furnace atmosphere on the surface carbon content of W2 tool steel. Specimens were heated at 790°C (1450°F) for 1 hour, quenched in brine, annealed in lead at 705°C (1300°F), and machined in 0.13 mm (0.005 in.) cuts for analysis.
Oxidizing atmospheres are inexpensive, and are usually produced by controlled direct-firing burners. The light scale that is produced is removed by the vigorous water or brine quench. Endothermic atmospheres also are used, but close control is necessary to match the carbon potential of the atmosphere to the carbon content at the surface.
Volume 4D, Heat Treating of Irons and Steels -> Tool Steels -> Heat Treating of Cold-Work Tool Steels—Low- and Un-Alloyed Water and Oil Hardening Steels -> Water-Hardening Tool Steels
