Quantitative evaluation in hot workability of SUS303 free-cutting steel

The hot forging behavior of S-containing SUS303 free-cutting steel was investigated in detail by carrying out compression tests; the tests were carried out in the temperature range of 1073-1323 K and strain rates ranging from 0.01 to 30 s−1. Quantitative relationships among the Zener-Hollomon parameter Z, dynamic recrystallization (DRX) fraction and power dissipation efficiency were discussed for the first time. The processing map exhibited high reliability in predicting the stable condition of low strain rate and high temperature, while at high strain rate region the reliability is relatively low. At the optimum condition predicted by the processing map, refined and uniaxial microstructure could be obtained, and at the same time the cutting ability was also enhanced greatly due to the re-distribution of MnS precipitates into a more suitable condition for the cutting process.