SUS304不锈钢近平衡凝固过程微观组织实验研究

Microstructural evolution in SUS304 stainless steel during solidification

采用真空电弧炉将SUS304试样熔化后以一定的冷速冷却到不同的温度,快速液淬后观察其微观组织形貌.结果表明,304不锈钢的凝固过程分为两部分,首先是初生铁素体的析出过程,然后是三相反应过程;树枝状铁素体直接从溶液中析出,到达三相反应区后析出团状和孔状共晶团;由于受冷却速度的影响,细小的铁素体薄片转变成奥氏体,粗大的初生枝状铁素体无法完全转变,从而以骨骼状铁素体的形态存在于最终的微观组织中.

SUS 304 was melted in the vacuum arc furnace and then cooled under certain cooling rate at different temperature.The microstructure evolution during solidification of SUS304 stainless steel was studied by quenching methods.Experimental results show that the phase transformation sequence in the steel is that the precipitation of primary ferrite dendrites takes place first,followed by ferrite-austenite eutectic reaction;the precipitation of ferrite dendrites is formed directly from the melt.At the eutectic reaction stage,a lot of porous eutectic and clusters of eutectic are observed;lamellar ferrite is transformed into austenite under the influence of the cooling rate,and the skeletal ferrite is obtained from the incomplete transformation of the primary ferrite dendrites.