摘要
对表面通过喷丸预变形后的定向凝固DZ4板材试样进行1220℃/4h的热处理,以在板材试样表面形成再结晶层。在760℃下进行疲劳试验,以研究表面再结晶层对定向凝固DZ4合金板材的疲劳性能的影响。结果表明,表面有再结晶层的定向凝固DZ4板材试样的疲劳性能大大降低,且疲劳寿命随着再结晶层深度的增大而降低;断口观察表明,疲劳裂纹均起源于表面的再结晶区或其与基体的界面。通过有限元模拟对含再结晶区的板材试样的损伤演化行为进行模拟,结果表明再结晶区的存在改变了试样表面的应力场分布,再结晶区与基体的界面上的应力最大,裂纹一般从此处萌生,并向表面和基体扩展。
Board specimens of directionally solidified DZ4 superalloy after shot-peening were heated at 1220℃ for 4h to prepare recrystallized layer at the surface. Then fatigue experiments at 760℃ were carried out in order to research the effect of recrystallized layer on the fatigue properties of the board specimens. The results show that fatigue properties greatly decrease and the fatigue lives decrease with the increment of the depth of recrystallized layer. Fatigue cracks initiate from the recrystallized zone or the interface with matrix. Analogy calculation was carried out to simulate the damage evolutionary process with finite element analysis. The results show that stress field is changed because of the existence of recrystallized zone and stress at the interface between recrystallized zone and matrix is largest. So fatigue cracks initiate at the interface and propagate to the surface and the matrix.
出处
《材料工程》
EI
CAS
CSCD
北大核心
2008年第6期64-67,71,共5页
Journal of Materials Engineering
关键词
定向凝固合金
再结晶
疲劳
界面
损伤演化
directionally solidified superalloy
recrystallization
fatigue
interface
damage evolution
