Ti/Al比对GH984G合金长期时效过程中γ′沉淀相粗化行为及拉伸性能的影响  

INFLUENCE OF Ti/Al RATIOS ON γ′ COARSENING BEHAVIOR AND TENSILE PROPERTIES OF GH984G ALLOY DURING LONG-TERM THERMAL EXPOSURE

作　　者：谭梅林[1] 王常帅[1] 郭永安[1] 郭建亭[1] 周兰章[1] 

机构地区：[1]中国科学院金属研究所,沈阳110016

出　　处：《金属学报》2014年第10期1260-1268,共9页Acta Metallurgica Sinica

基　　金：国家高技术研究发展计划项目2012AA03A501;国家自然科学基金项目51301171;国家能源局项目NY20110102-1;中国科学院-四川省成果转化项目资助~~

摘　　要：研究了2种Ti/Al比对新型Ni-Fe-Cr基合金GH984G在长达上万小时高温时效过程中γ′淀相的粗化行为及其拉伸性能的影响规律.结果表明：随时效温度从700℃升高至800℃,球形γ′沉淀相的粗化速率明显增大.在700和750℃长期时效过程中,高Ti/Al比和低Ti/Al比合金γ′沉淀相的粗化行为均符合Lifshitz-Slyozof-Wagner（LSW）理论,受扩散过程控制,高Ti/Al比合金中γ′沉淀相的粗化速率较高.800℃长期时效过程中,2种Ti/Al比合金γ′沉淀相的粗化行为偏离LSW理论.此外,时效时间小于3×103h时,高Ti/Al比合金的γ′沉淀相长大较快,进一步延长时效时间,低Ti/Al比合金的γ′沉淀相长大速率较快.Ti/Al比对合金标准热处理态和700~800℃时效10480 h后合金的700℃拉伸性能无明显影响.通过选取合适的Ti/Al比,可以控制γ′沉淀相的粗化行为,增强合金组织稳定性.GH984G is a new Ni-Fe-Cr base alloy which has been designed for use as superheater,reheater and header materials for boilers in 700 ℃ advanced ultra-supercritical（A-USC） coal-fired power plants.Compared with the CCA617,Nimonic 263 and IN 740 alloys,the GH984 G is an economic alloy due to the elimination of Co and it containing more than 20%Fe.As a precipitation hardened alloy,the size of γ′ precipitates has great influence on the tensile properties.The γ′ precipitates become coarse during long-term thermal exposure.The coarsening behavior of γ′ precipitates is closely related with Ti/Al ratio.However,there are few investigations about the influence of Ti/Al ratio on the coarsening behavior of γ′ precipitates of GH984 G alloy.Therefore,in this work,the coarsening behavior of γ′ precipitates and its influence on tensile properties of GH984 G alloy with two Ti/Al ratios was investigated during long-term thermal exposure.The results show that the growth kinetic of the γ′ precipitates can be explained by Lifshitz-Slyozov-Wagner＇s theory of element diffusion controlled coarsening during long-term thermal exposure at 700 and 750 ℃.The rate of γ′ precipitates growth of the alloy with high Ti/Al ratio is higher.At 800 ℃,the rate of γ′ precipitates growth decreases with increasing the thermal exposure time.The coarsening behavior does not follow the Lifshitz-Slyozov-Wagner＇s theory.The reasons are attributed to the effect of elastic interaction energy and the depletion of γ′-forming elements in g matrix.The Ti/Al ratio has no obvious influence on700 ℃ tensile properties during long-term thermal exposure between 700 and 800 ℃.The 700 ℃ yield strength has no obviously decreases even if after thermal exposure at 700 ℃ for 10480 h.The ductility increases after thermal exposure at 800 ℃.The variation of strength and ductility is attributed to the coarsening of γ′ precipitation.The deformation mechanism is the moving dislocations shear γ′ precipitates and the stacking faul

关 键 词：Ni-Fe-Cr基合金 长期时效 γ′沉淀相 粗化行为 拉伸性能 

分 类 号：TG111.8[金属学及工艺—物理冶金]