Solar Atmospheres of Western PA commissioned a 20-foot-long car-bottom air furnace with a total load capacity of up to 30,000 pounds. The Class 2 furnace, built by Heat Treat Equipment Inc. of Canton, Mich., was installed and fully tested in Hermitage, Pa. The 60-inch-square x 240-inch hot zone passed the AMS 2750E temperature uniformity survey of +/- 10°F from temperatures of 300-1450°F. The furnace passed the survey on the first attempt and was put into production immediately.
The furnace will serve to complement Solar’s lower-temperature work, especially where surface oxidation is of little concern. It will also be used to economically process many downstream processes, including multiple tempering operations, which typically follow vacuum austenitizing treatments.
Figure 1 shows the inaugural run of six 4140 rolls that weigh a total of 12,000 pounds. The rolls are used for a variety of steelmaking industries from forming angles to rolling rebar. The consolidated powdered metal on the major diameters is hot isostatically pressed and must be hardened. Following a vacuum austenitizing treatment at 2075°F, the rolls are quickly nitrogen-quenched. It is necessary to immediately temper the resultant HRC 60 surface hardness on the major diameters. Instead of reloading back into Solar’s large vacuum furnaces, the rolls are transferred to this car-bottom air furnace for triple tempering operations ranging from 1000°F to 1150°F.