高温均匀化对GH4710镍基合金组织及性能的影响

Effect of High Temperature Homogenization on Microstructure and Properties of GH4710 Nickel Base Alloy

对真空感应+真空自耗双联工艺冶炼的GH4710镍基合金铸锭进行两段式高温均匀化热处理,采用金相显微镜观察了热处理前后铸锭的微观组织和晶粒尺寸,利用扫描电镜、电子探针对热处理前后铸锭中合金元素的分布及含量进行测定,计算了铸锭不同部位各种元素的偏析指数。研究结果表明,采取(1 150±10)℃×30 h-(1 200±10)℃×50 h的二段式热处理工艺,有效消除了GH4710镍基合金铸锭组织中的共晶相,降低了铸锭成分偏析,显著提高锻造棒材的力学性能。在980℃,120 N/mm^(2)的试验条件下,持久性能达到了126、134 h,较铸锭未均匀化生产的53、74 h,提高了一倍左右,持久伸长率也提高了50%以上。

GH4710 nickel base alloy ingots,melted by VIM plus VAR,were subjected to trails of two-stage hightemperature homogenizing heat treatments,the microstructure and grain size of the ingots before and after heat treatment were analyzed by metallographic microscop.the distribution and content of alloy element in the ingot before and after heat treatment were evaluated by scanning electron microscope and electron probe,as well as to calculate the segregation index for alloying elements in different positions of ingots.Test result verified that,the two-stage homogenizing heat treatment at(1150±50)℃×30 h-(1200±10)℃×50 h,it could significantly eliminate the eutectic phase in the structure of GH 4710 ingot and reduce the element segregation in the ingot,and the mechanical properties of the forged bar are improved significantly.Under the test conditions of 980℃,120 N/mm^(2),the persistence performance reached 126 h and 134 h,which was about double improvement compared with 53 h and 74 h of un-homogenizing heat treatment production.The persistent elongation rate has also increased by more than 50%.