摘要
通过熔模铸造的方法制备了ZTA7合金试样,对试样进行α层检测和补焊。利用光学显微镜(OM)、能谱仪(EDS)、显微硬度测试仪等检测了ZTA7铸件基体和α层的组织、成分和显微硬度,分析了铸件补焊裂纹的开裂位置和形式,研究了α层对开裂的影响规律。研究结果表明:铸件补焊周围的裂纹无规则分布在焊接热影响区及邻近热影响区的母材表层。铸件内部基体为具有原始β相晶界的片状α组织,表层为粗大的片状α组织。脆硬的α层和焊接热循环过程中产生的焊接应力共同导致铸件表层开裂,且开裂率随着α层厚度的减小而降低。表面α层厚度低于55μm时才能显著降低铸件补焊后的开裂机率。要完全避免补焊开裂,应以硬度值为依据,全部去除铸件表面α层。
The sample of ZTA7 alloy were prepared by investment casting. The α layer in the sample was tested and the repair welding test was carried out. Microstructures, chemical compositions and microhardness of the matrix of ZTA7 casting and α layer were tested by optical microscope(OM), energy dispersive spectrometry(EDS) and Vickers hardness tester. The locations and forms of repair welding cracks of the casting were analyzed, and the influence of α layer on the crack was studied. The results show that the welding cracks are distributed irregularly on the heat affect zone(HAZ) and matrix surface layer near the heat affected zone. The internal matrix of the castings is composed of schistose α phase with β boundary, and the surface structure is coarse α. The cracks on the surface of casting are caused by the α layer and the stress produced in the weld thermal cycle process, and the cracking rate decreases with the reduce of the thickness of α layer. The probability of welding crack can be reduced obviously when the thinkness of α layer is less than 55μm. In order to completely avoid cracking, the α layer on the surface should be completely removed, which should be based on the hardness value.
作者
张帅锋
张建欣
于冰冰
尹艳超
孙宏喆
ZHANG Shuaifeng;ZHANG Jianxin;YU Bingbing;YIN Yanchao;SUN Hongzhe(Luoyang Ship Material Research Institute,Luoyang 471039,China)
出处
《热加工工艺》
北大核心
2020年第3期67-70,共4页
Hot Working Technology
关键词
ZTA7
α层
补焊裂纹
熔模铸造
显微硬度
ZTA7
α-case layer
repair welding crack
investment casting
microhardness
作者简介
张帅锋(1989-),男,河南洛阳人,工程师,硕士,主要研究方向:钛合金焊接、增材制造,电话:0379-67256263,E-mail:zhsf@tju.edu.cn
