September 5, 2014
Solar Atmospheres has developed a three-step heat-treat process to austenite condition, in situ cool, and bright age harden 17-7 precipitation hardenable (PH) stainless steel in a vacuum furnace without breaking vacuum. This is desirable because it is difficult to keep 17-7 bright during the PH treatment after breaking vacuum and exposing parts to ambient atmosphere required for adequate cooling, where it can discolor from oxidation.
The three-step process has resulted in a new condition of 17-7 that the company has coined SH 950. Compared to standard 17-7 condition TH 1050, condition SH 950 shows comparable yield strength, higher tensile strength, and an average of twice the ductility, says the company. These tensile properties were obtained with two different heats of steel with three tensile specimens tested for both heats and conditions, resulting in 12 separate tensile test results.