Development of welding technology for improving the metallurgical and mechanical properties of 21st century nickel based superalloy 686
Development of welding technology for improving the metallurgical and mechanical properties of 21st century nickel based superalloy 686
复制标题
DOI：
10.1016/j.msea.2017.03.042
复制
发表时间：
2017-04-13
期刊：
影响因子：
6.4
通讯作者：
Manikandan, M.
中科院分区：
文献类型：
--
作者：
Arulmurugan, B.;Manikandan, M.
合金 686 是一种源自 Ni-Cr-Mo 三元系的高耐腐蚀性 21 世纪镍基高温合金。添加合金元素铬（Cr）和钼（Mo），提高了在广泛使用环境下的耐腐蚀性。较高比例的合金元素 Cr 和 Mo 的存在会导致镍基高温合金的微观偏析，并最终导致熔融区产生热裂纹。然而，关于 686 合金焊接中合金元素微观偏析的信息很少。本研究探讨了降低微观偏析以减少熔融区第二相形成的可能性。焊接接头采用 ERNiCrMo-10 填充物和无填充焊丝（自熔）模式的钨极气体保护焊 (GTAW) 和脉冲电流钨极气体保护焊 (PCGTAW) 制造。利用光学和扫描电子显微镜（SEM）研究了焊接接头的微观结构性能。采用脉冲电流（PC）技术制造的接头显示出精细的微观结构、更窄的焊道并且几乎没有热影响区（HAZ）。扫描电子显微镜证明 GTAW 情况的枝晶间区域存在第二相。进行能量色散X射线光谱（EDS）分析来评估合金元素的微观偏析。结果表明，无论是自生焊丝还是填充焊丝，在 GTAW 的枝晶间区域都观察到了 Mo 的偏析。进行拉伸和冲击测试以评估焊接接头的强度、延展性和韧性。结果表明，与各自的 GTAW 相比，PCGTA 有助于提高焊接接头的强度、延展性和韧性。无论本研究中采用何种焊接类型，弯曲测试都不会导致裂纹。
Alloy 686 is a highly corrosion resistant 21st-Century Nickel based superalloy derived from Ni-Cr-Mo ternary system. The alloying elements chromium (Cr) and molybdenum (Mo) are added to improve the resistance to corrosion in the broad range of service environment. The presence of a higher percentage of alloying elements Cr and Mo lead to microsegregation and end up with hot cracking in the fusion zone of Nickel-based superalloys. However, there is scanty of information regarding the welding of alloy 686 with respect to the microsegregation of alloying elements. The present study investigates the possibility of bringing down the microsegregation to cut down the formation of secondary phases in the fusion zone. The weld joints were fabricated by Gas Tungsten Arc Welding (GTAW) and Pulsed current gas tungsten arc welding (PCGTAW) with ERNiCrMo-10 filler and without filler wire (autogenous) mode. The microstructural properties of the weld joints were studied with optical and Scanning Electron Microscope (SEM). The joints fabricated by pulsed current (PC) technique shows refined microstructure, narrower weld bead and practically no heat affected zone (HAZ). Scanning Electron Microscope demonstrates the presence of secondary phases in the interdendritic regions of GTAW case. Energy Dispersive X-ray Spectroscopy (EDS) analysis was carried out to evaluate the micro segregation of alloying element. The results show that the segregation of Mo noticed in the interdendritic zone of GTAW both autogenous and filler wire. Tensile and Impact tests were done to evaluate the strength, ductility, and toughness of the weld joints. The results show that the PCGTA helps to obtain improved strength, ductility and toughness of the weld joints compared to their respective GTAW. Bend test did not lead to cracking irrespective of the type of welding adopted in the present study.