焊接参数对Ni60合金等离子堆焊层组织结构和显微硬度的影响
Influence of Parameters on Microstructure and Microhardness of Ni60 Alloy Hardfacingby Plasma Transferred Arc Welding
葛言柳 1邓德伟 1田鑫 2关锰2
作者信息
- 1. 大连理工大学材料科学与工程学院,辽宁大连116024
- 2. 沈阳鼓风机集团,沈阳110869
- 折叠
摘要
采用等离子堆焊技术在Z2CN18-10不锈钢表面堆焊Ni60合金粉末熔覆层.应用扫描电镜、电子探针、X-射线衍射仪、显微硬度计等测试手段,研究焊接电流和送粉速度对Ni60合金等离子堆焊层组织结构和显微硬度的影响.结果表明:堆焊层显微硬度较基材有明显提高,并且在熔合区域出现明显的硬度过渡和元素扩散区.焊接电流为110 A时堆焊层显微硬度为630 HV.随着焊接电流增大或送粉速度降低,堆焊层硬度和熔合区硬度梯度均明显降低.堆焊层出现了明显的组织梯度,包括熔合区、近熔合区树枝晶区(针状、条状、小花状)和近表层等轴晶区(块状、片状).焊接电流增加,近表面区域小花状共晶结构并未消失,体积含量增大.送粉速度降低,堆焊层近熔合线区域针状结构变粗大.送粉速度为6 g/min时,堆焊层中部区域出现了具有方向性的长条状和分离的块状硼化物.
Abstract
The Ni60 alloy powder was deposited on the surface of Z2CN18-10 stainless steel by plasma transferred arc welding. The microstructure and microhardness of the hardfacing with different welding currents and powder feed rates were characterized by scanning electron microscope, X-ray diffraction, electron microprobe and hardness tester. The results show that the microhardness of the coating improves a lot, the phenomenon of hardness transition and elements diffusion is observed in the fusion area. The microhardness of coating with current of 110 A is about 630 HV while the hardness of the coating and the hardness gradient both decrease with higher currents or lower powder feed rates. Micro-structural gradient is observed including fusion area, dendrite (needle-like, strip-like and floret-like) near the interface and equiaxial structure (bulk-like and plate-like) near the surface in the coating. As current increases, the floret-like eutectic structures don't disappear and the volume ratio increases. As powder feed rate decreases, the needle-like structures become more bulky. The strip - like and separated bulk - like borides are observed in the intermediate part of the coating with powder feed rate of 6 g/min.
关键词
等离子堆焊/电流/送粉速度/显微组织/显微硬度Key words
plasma transferred arc welding (PTAW)/current/powder feed rate/microstucture/microhardness引用本文复制引用
出版年
2011
NETL
NSTL
维普
万方数据