摘要
使用电子束对DD407单晶高温合金进行焊接,采用光学显微镜和扫描电镜观察分析了熔凝区裂纹形态及分布特征,采用EDS测定了试样枝晶干与枝晶间区域的化学成分,计算了元素的偏析比并分析了裂纹形成原因。结果表明:在电子束热作用下,DD407单晶熔凝区中主要产生纵向裂纹、横向裂纹、弧坑裂纹、晶间裂纹,当其它工艺参数不变时,熔凝区凝固裂纹含量随着电子束流的增大先增大后减小;DD407单晶在焊接凝固过程中,杂晶区合金元素偏析严重,导致低熔点共晶组织聚集并形成低熔点液态薄膜,在凝固收缩拉应力作用下,使得杂晶区常形成凝固裂纹。
Nickle base single crystal superalloys DD407 were welded by electron beam welding. The morphology and distribution of cracks were analyzed by optical microscopy and scanning electron microscopy. The chemical composition between dendrite arm and interdendritic area was measured by EDS. The segregation ratio of elements was calculated and the cause of cracks formation was analyzed. The results show that longitudinal cracks, transverse cracks, crater cracks and intergranular cracks are mainly produced in a fused region of DD407 with the thermal effect of the electron beam. With the increasing of electron beam current, the content of solidification cracks increases firstly and then decreases when other parameters remain unchanged. Low melting point eutectics gather and form a low-melting liquid film due to the serious segregation of alloying elements in miscellaneous grain zone. Therefore, the solidification cracks are often formed in miscellaneous grain zone with the solidification shrinkage tensile stress.
出处
《稀有金属材料与工程》
SCIE
EI
CAS
CSCD
北大核心
2017年第7期1920-1923,共4页
Rare Metal Materials and Engineering
基金
国家自然科学基金(51365044)
先进焊接与连接国家重点实验室开放课题(AWJ-M13-09)
关键词
单晶高温合金
裂纹
电子束焊
single crystal superalloys
cracks
electron beam welding
