GH4738合金高温扩散退火工艺

High-temperature diffusion annealing process of GH4738 alloy

借助于Thermal-calc热力学软件计算了合金的平衡凝固相图,以此为依据制定了高温扩散退火处理的试验参数。利用OM和SEM观察了GH4738合金的铸态偏析状况,并用EPMA技术研究了合金铸态以及不同高温扩散退火制度下的元素偏析规律。结果表明,铸态合金中Ti元素偏析最为严重,高温扩散退火处理后Ti元素偏析得到明显改善,经1200℃×50 h的高温处理后效果最为显著,同时计算了残余偏析指数随温度的变化曲线,计算结果和试验结果基本吻合。

Equilibrium solidification phase diagram of GH 4738 superalloy was calculated by using Thermal-calc software,based on which experimental parameters of homogenization treatment was established.The segregation of as-cast GH4738 superalloy was observed by using OM and SEM,the laws of element segregation in the as-cast alloy with as-cast and different diffused annealing state at different temperatures were studied by using EPMA technique.The results show that Ti element segregation is the most serious in the as-cast alloy,the segregation of Ti element is significantly improved after the alloy treated by high-temperature diffusion annealing process,and the effect is the most significant after annealing at 1200℃for 50 h.Meanwhile,the change curves of the residual segregation index versus temperature is calculated,and the calculated results are basically in accord with the experimental results.