摘要
以单晶高温合金CMSX-4为研究对象,设计制备一种含5层平台的单晶试板铸件,研究其在不同温度下进行固溶热处理后的再结晶行为。结果表明:经固溶热处理后除最下层平台外,其余每层平台的截面突变处均有再结晶产生,再结晶面积随平台所处高度的增加先增大后减小;铸件外侧平台比内侧平台更容易产生再结晶。固溶热处理温度T_(H)对铸件平台再结晶形核和长大的影响非常显著,当T_(H)从1303℃提升到1315℃时,再结晶面积从9.7 mm^(2)增加到293 mm^(2),增幅高达30倍。由于截面突变,铸件平台部位会在凝固及冷却过程中产生较大的塑性变形并积聚大量的变形能,在后续热处理时截面突变处易成为再结晶的起源;同时,因凝固过程中换热条件、冷却速率和变形速率的差异,导致铸件各部位的应力分布不均,在固溶热处理后表现出不同的再结晶行为。此外,提高T_(H)能够有效促进γ/γ′共晶组织和粗大γ′相的溶解,减少γ/γ′共晶组织及粗大γ′相对再结晶晶界迁移过程中的钉扎作用,显著增加再结晶缺陷区域。
Single crystal plate castings of superalloy CMSX-4 were prepared,providing simplified geometries of turbine blades featured with five stage platforms.The recrystallization behavior in the plate castings was investigated after solution heat treatments at different temperatures.The results show that after solution heat treatment,recrystallization occurs at the abrupt cross-section of every platform except the lowest one.The recrystallization area increases and then decreases as the platform's height increases.The outside platform of the casting is also more likely to result in recrystallization than the inside one.The nucleation and growth of the recrystallization grains are significantly influenced by the solution heat treatment temperature(T_H).When T_(H) is raised from 1303 ℃ to 1315 ℃,the recrystallization area increases by_(3)0 times,from 9.7 mm^(2) to_(2)93 mm^(2).Because of the abrupt section transition,the platform part of the casting will produce more plastic deformation and accumulate a large amount of deformation energy during solidification and cooling,and the abrupt change in cross-section will easily become the source of recrystallization during the subsequent heat treatment.Meanwhile,the difference in heat exchange conditions,cooling rate and deformation rate during solidification leads to uneven stress distribution.As a result,different recrystallization behaviors appear after solution heat treatment.Furthermore,increasing T_(H) can effectively promote the dissolution of γ/γ′ eutectics and coarse γ′ phase,reduce the pinning effect of residual γ/γ′ eutectics and coarse γ′ phase in the recrystallization grain boundary migration process,and significantly increase the recrystallization defect area.
作者
徐福泽
蔺永诚
马德新
赵运兴
何道广
刘冠
XU Fuze;LIN Yongcheng;MA Dexin;ZHAO Yunxing;HE Daoguang;LIU Guan(School of Mechanical and Electrical Engineering,Central South University,Changsha 410083,China;Shenzhen Wedge Central South Research Institute Co.,Ltd.,Shenzhen 518045,Guangdong,China;Powder Metallurgy Research Institute,Central South University,Changsha 410083,China)
出处
《材料工程》
EI
CAS
CSCD
北大核心
2023年第10期42-50,共9页
Journal of Materials Engineering
基金
国家自然科学基金项目(91860103,92060104)
中南大学研究生科研创新项目(自主探索)(1053320184004)
深圳市海外高层次人才基金资助(KQTD2015032716463668)
广东省引进创新创业团队项目资助(607264877417)。
关键词
单晶高温合金
CMSX-4
再结晶
塑性应变
数值模拟
single crystal superalloy
CMSX-4
recrystallization
plastic strain
numerical simulation
