刘坡
,
宗影影
,
郭赋
,
单德彬
材料研究学报
蠕变或应力松弛被认为是钛合金板材热成形降低回弹的主要机理.目前对热校形阶段中的蠕变与应力松弛的区别及联系尚缺乏深入研究.本文主要进行了钛合金高温短时蠕变及应力松弛实验,利用TEM对实验后的显微组织进行了观察.分别研究了温度、应力及时间对蠕变和应力松弛行为的影响规律,从蠕变率-时间和蠕变-时间角度建立了蠕变与应力松弛之间的联系.研究表明:钛合金在低温低应力下蠕变以原子扩散为主,高温高应力下以位错滑移和攀移为主,而应力松弛在不同温度时均以位错攀移为主要变形机制,基于蠕变数据预测的应力松弛行为与实验结果符合较好.
关键词:
金属材料
,
钛合金
,
蠕变
,
应力松弛
,
蠕变率
S.H.Ai
,
Y.B.Xia and J.F.Tian (State Key Laboratory for Fatigue and Fracture of Materials
,
Institute of Metal Research
,
The Chinese Academy of Sciences
,
Shenyang 110015
,
China)
金属学报(英文版)
The creep and fracture behavior of the cast K417 and forged GH4049 nickel-based superalloys were investigated in the temperature range of 700-900℃ C. Within the ranges of stress and temperature studied, the steady state creep rates exhibited a power law relationship with the applied stress and temperature. The time to rupture is inversely proportional to the steady state creep rate. Under all testing conditions, the creep fracture process was mainly controled by crack initiation and growth of the intergranular oxidation. Casting porosities, pores and carbides were also prefecentral locations of creep crack initiation in the cast K417 alloy. In addition, the intergranular fracture feature in the forged GH4049 alloy was apparently associated with the formation and coalescence of the cavitations on the grain boundaries.
关键词:
superalloy
,
null
,
null
