Cr16Mn9Cu2Ni1N低镍奥氏体不锈钢凝固组织研究

Study on Solidification Microstructure of Cr16Mn9Cu2Ni1N Low Nickel Austenitic Stainless

低镍奥氏体不锈钢冷却模式为先析出δ铁素体,随后转变为奥氏体,晶核中的δ铁素体被保存下来。随着冷却速度的变化,凝固模式发生变化。在冷却速度不太快的近表面层,可得到接近平衡态的枝晶组织,残留δ铁素体为骨架形或蠕虫状,奥氏体全部为δ铁素体通过固态相变转变而来。在冷却速度较快的表面层,凝固模式偏离平衡态,δ铁素体作为先析出相在液相中形核长大的同时,剩余的液相转变为共晶奥氏体。

During the cooling process, ferrite is the first phase to precipitate in low nickel austenitic steel, then it will be transformed into austenite and delta-ferrite in the nucleus is retained. With the change of colling rate, the solidification modes changes. Near the surface where the colling rate is not high, the near-bal？anced dendrite structure can be obtained.The retained delta-ferrite are vermiform or of skeleton frame and all austenite are transformed from delta-ferrite by solid phase transformation. On the surface where the colling rate is very high, the solidification mode deviate from the balance;as primary-precipitated phase, delta-fer？rite form first from the liquid while the remaining liquid phases are transformed to eutectic-austenite.