2014 Volume 54 Issue 8 Pages 1920-1926
Effects of temperature and oxygen concentration on decarburization of 55SiCr spring steel were investigated at the temperature range of 500°C–1200°C by using a Muffle furnace (an atmosphere of ambient air) and a Simultaneous Thermal Analyzer (low oxygen concentration with 2% O2 and 98% N2). In ambient air, the decarburization behavior can be divided roughly into five temperature ranges: T≥1200°C, no decarburization; TG (A3 for 55SiCr when its carbon concentration equals to zero)<T<1200°C, partial decarburization; A3<T<TG, complete and partial decarburization; T<A3, complete decarburization; T<A1, no decarburization. However, it is observed that complete decarburization did not occur in all the testing temperature ranges under low oxygen concentration. For 55SiCr spring steel, decarburization behavior under low oxygen concentration can be divided into two regions: T<700°C, no decarburization; T>700°C, only partial decarburization. Lower oxygen concentration results in decrease in a growth rate of the oxide scale and leads to different characteristics of decarburization.
