回炉料对K441合金性能及杂质元素含量的影响

Effect of Returns on Properties and Impurity Elements Content of K441 Superalloy

通过采用真空感应熔炼法,对K441合金回炉料进行了四次熔炼,研究了回炉料对K441合金持久寿命、力学性能、杂质元素含量及微观组织形貌的影响。结果表明,经过四次回炉熔炼后合金的持久性能均满足标准的要求。合金的抗拉强度及塑性与新料合金相比变化幅度不大,但第四次回炉料合金的抗拉强度较高,这主要是由于Si元素的固溶强化作用所致。随回炉料合金回炉次数的增加,合金中的S元素含量降低,Mn含量变化幅度不大,P、Si元素含量增加。合金微观组织形貌观察表明,新料合金与回炉料合金中的碳化物均沿晶界分布,新料合金中晶粒内也存在部分碳化物。回炉料合金中的晶界存在杂质增加的现象。新料合金及回炉料合金中的γ′相数量相当,含量都较少,经多次回炉熔炼后合金中的γ′相尺寸减小。

By adopting the vacuum induction melting, K441 superalloy returns was melted four times and the creep life, mechanical properties and content of impurity elements of superalloy were determined. The effects of returns on creep life, mechanical properties, impurity element content and microstructure of K441 superalloy were studied. The results show that, after four times smelting the creep life of alloy meets requirement, the creep life of alloy using returns compared with fresh alloy changes little, and the tensile strength and plasticity changes little, but the fourth returns alloy tensile strength is higher, this is mainly due to the Si element solution strengthening. With the recycle times increasing of returns alloy, the S content decreased in the alloy and the Mn content changed little, but the content of P and Si increased. The observations of microstructure show that the carbide distributed along the grain boundaries in fresh alloy and returns alloy, and some carbide exist in the flesh alloy. There is a phenomenon that impurities increase at grain boundaries in returns alloy. The content of γ′ phase in fresh alloy and returns alloy is fewer, but the alloys possess the same content of γ′ phase, but the γ′ phase size in returns decreased after many times recycling.