Effect of δ Phase on Microstructure and Hardness of Heat-Affected Zone in TIG-Welded GH4169 Superalloy

• 来源期刊: 金属学报（英文版）
• 年，卷（期）: 2019,（8）
• 页码范围: 1041-1052
• 页数: 12页
• 语种: 英文

摘要

The GH4169 superalloy with different content of δ-Ni3Nb phase was welded by tungsten inert gas welding.A detailed study of microstructure and hardness of heat-affected zone (HAZ) was performed in both as-welded and aged state.The results show that the precipitation of δ phase,especially the intergranular δ phase,can lead to the enrichment of Nb and Mo elements,which promote the formation of γ/Laves eutectic constituent at grain boundaries in HAZ.In as-welded state,the hardness decreases first and then increases (exhibiting a “V” shape) with distance away from fusion line in HAZ,which is governed by grain size.After aging treatment,however,the γ''phase plays a key role in hardness and leads to the “∧” shape profiles of hardness in HAZ.