高氮奥氏体不锈钢的δ相转变研究

Research on δ Phase Transition in High Nitrogen Austenite Sainless Steel

分别用金相法和铁素体测量仪测量0Cr20Mn19N0.58高氮奥氏体不锈钢铸态、锻态和固溶态组织中的δ相含量。结果表明:不同测量方法下铸态和锻态组织的测量结果存在显著差异,而固溶态组织的测量结果基本相符。形成这一现象的原因是:0Cr20Mn19N0.58高氮奥氏体不锈钢的凝固模式为FA模式,该模式下凝固过程中生成的δ相在1000℃以下发生δ→σ+γⅡ的相转变,由磁性相转变为非磁性相;在1000℃以上会发生σ+γⅡ→δ的相转变,由非磁性相转变为磁性相。

The δ phase content in casting, forging and solution structures of 0Cr20Mn19N0.58 high nitrogen austenite stainless steel was measured by metallograph method and ferrite measuring instrument, respectively. The results show that phase contents in casting and forging structures measured by different methods are obviously different. But the measured results are consistent in solution structure. The reasons for the phenomenon are that the solidificaiton mode of 0Cr20Mnl9N0.58 high nitrogen austenite stainless steel is FA mode. Under this mode, the δ phase forming during solidificaiton generates δ→σ＋γ. phase transition when the temperature is below 1000 ℃, and the magnetic phase transtbrms to nonmagnetic phases. The σ＋γ→δ phase transition appears when the temperature is above 1000 ℃, and the nonmagnetic phases transforms to magnetic phase.