WHAT TO LOOK FOR IN PRECISION THREAD GAUGING

Raw Material and Heat Treatment Stabilization Process
Gauge material and heat treatment play a very important role in obtaining a dimensionally stable and long life gauge. We use an OHNS Tungsten quality oil hardened nonshrinking steel or a 20MnCr5 steel (for small thread rings). The gauge material is duly carburized hardened and tempered. Cryogenic treatment is carried out to increase the performance of the material. This cryogenic treatment is not a substitute for heat treatment, but rather an extension of the heating, quenching, and tempering cycle. The process involves a slow controlled cooling, holding at cryogenic temperature for a specific hold time and then allowing to return to room temperature slowly. This process transforms all retained austenite to martensite. The end result is a very stable material which is 100% martensite and very hard RC 58-62. Without cryogenic treatment, these steels may contain significant amounts of retained austenite which is a weak, soft, easily abraded micro constituent of steel.