Exploring the Effect of Sub-zero Treatment on the Performance of Steel Grades

Sub-zero treatment (SZT) is a low-temperature treatment used to improve the mechanical properties of ferrous and non-ferrous alloys. Such treatment is gaining interest on an industrial scale due to the attainable privileges, such as longer service life, better mechanical properties, and enhanced wear resistance. This study investigates the effect of deep cryogenic treatment (DCT) on the mechanical properties, hardness, and surface finish of different soft steel grades. The DCT process, conducted in this investigation, utilized a low-cost setup to carry out an 8-h ramp from ambient temperature down to -190 ℃ at a slow cooling rate, followed by 24 h at −190 ℃, and then ramped up to ambient temperature at a slow heating rate. Four different grades of steel were used in the current investigation: cast iron, 304SS, CD4MCu, and 17-4PH stainless steel. For all grades of steel, results show an improvement in the surface bearing area of cryo-treated 304SS and 17-4PH samples compared to non-treated conditions. Moreover, enhanced strength and hardness values were reported for certain steels after applying that DCT protocol.