双时效工艺对SLM成形GH4169合金组织与拉伸性能的影响  

Effect of two-step aging process on microstructure and mechanical properties of SLM-GH4169 alloy

作　　者：倪磊 刘建华 王安东[1] NI Lei;LIU Jian-hua;WANG An-dong(School of Materials Science and Engineering,Jiangsu University,Zhenjiang 212013,China)

机构地区：[1]江苏大学材料科学与工程学院,江苏镇江212013

出　　处：《材料热处理学报》2022年第10期60-69,共10页Transactions of Materials and Heat Treatment

基　　金：国家自然科学基金(52175464)。

摘　　要：研究了不同双时效热处理工艺(一级时效温度为720、770和820℃及时间为1、2、4、8、16和32 h,二级时效温度为620℃及时间为8 h)对激光选区熔化成形的GH4169合金显微组织和力学性能的影响。结果表明:当合金在720℃时效时,晶内γ″相不断析出和长大,当时效时间小于16 h时,晶界处的δ相在形状和数量上均保持不变,当时效时间达到32 h,晶界上的δ相从短棒状转变为长针状,晶内γ″相大量转变为δ相。在770和820℃时效时组织演变与720℃时效类似,但是γ″相向δ相大量转变的起始时间分别提前到了4 h和2 h。不同温度时效处理的试样显微硬度随着时效时间的增加均表现出先增加后降低的趋势。在720℃时效16 h后,合金的硬度达到峰值,为485.6 HV5,而在770和820℃分别时效4 h和2 h后,合金的硬度达到峰值,分别为472.3和458.1 HV5。650℃拉伸性能测试结果表明第一阶段时效工艺分别为720℃×16 h,770℃×4 h,820℃×2 h的合金试样的抗拉强度分别为1201、1185和1053 MPa。合金的最佳双时效工艺为720℃时效16 h后炉冷2 h至620℃并保温8 h后空冷。Effect of different two-step aging heat treatment processes(firstly aging temperature of 720,770 and 820℃and time of 1,2,4,8,16 and 32 h,secondary aging temperature of 620℃and time of 8 h)on microstructure and mechanical properties of GH4169 alloy formed by selective laser melting(SLM)was studied.The results show that when the alloy is aged at 720℃,the intragranularγ″phase precipitates and grows continuously;when the aging time is less than 16 h,the shape and quantity of theδphase at the grain boundary remain unchanged;when the aging time reaches 32 h,theδphase at the grain boundary changes from short rod to long needle,and a large number of the intragranularγ″phase changes to theδphase.The microstructure evolution of the alloy aged at 770℃and 820℃is similar to that aged at 720℃,but the start time of the large transformation fromγ″phase toδphase is advanced to 4 h and 2 h respectively.The microhardness of the samples aged at different temperatures increases first and then decreases with the increase of aging time.After aging at 720℃for 16 h,the hardness of the alloy reaches a peak value of 485.6 HV5,while after aging at 770℃and 820℃for 4 h and 2 h,the hardness of the alloy reaches a peak value of 472.3 and 458.1 HV5,respectively.The tensile property test results at 650℃show that the tensile strength of the alloy samples with the first stage aging process of 720℃×16 h,770℃×4 h,820℃×2 h is 1201,1185 and 1053 MPa respectively.The optimal two-step aging process of the alloy is that it is aged at 720℃for 16 h,then cooled in furnace for 2 h to 620℃and held for 8 h by air cooling.

关 键 词：GH4169合金 激光选区熔化 双时效工艺 δ相析出 650℃拉伸性能 

分 类 号：TG132.3[一般工业技术—材料科学与工程]