焊后热处理对Q690D钢对接接头组织和性能的影响

doi:10.13251/j.issn.0254-6051.2025.05.032

摘要/Abstract

摘要： 研究了不同焊后热处理制度(580 ℃×2 h、450 ℃×8 h、450 ℃×4 h、450 ℃×2 h、250 ℃×2 h)下Q690D钢对接接头的力学性能和显微组织。结果表明,焊后热处理对接头强度的影响不大,但对其冲击性能的影响较大。当热处理温度高于Q690D钢的回火温度(480 ℃)时,焊缝、热影响区冲击性能下降明显,表现为准解理断裂;当热处理温度低于回火温度时,保温2 h后,焊缝、热影响区冲击性能有较大提升,表现为韧性断裂。当热处理温度低于回火温度30 ℃时,保温时长对热影响区冲击性能的影响较小,但过长的保温时间(8 h)会使焊缝冲击性能大幅下降,故保温时长不宜超过4 h。焊态接头热影响区存在硬化区和软化区,热处理后,硬化消除但软化略有加重。经过焊后热处理的焊缝组织主要为针状铁素体+粒状贝氏体,随着热处理温度的升高或保温时间的延长,晶界处析出明显碳化物,且针状铁素体平均针宽增大。

关键词: Q690D钢, 焊后热处理, 对接接头, 显微组织, 力学性能

Abstract: Mechanical properties and microstructure of Q690D steel butt joints under different post-weld heat treatment(PWHT) processes, namely, 580 ℃×2 h, 450 ℃×8 h, 450 ℃×4 h, 450 ℃×2 h, and 250 ℃×2 h, were studied and compared with those under welded state. The results show that PWHT has a little effect on strength, but has a significant influence on impact properties. When the heating temperature is higher than the tempering temperature(480 ℃) of the Q690D steel, the impact properties of the weld seam and heat affected zone(HAZ) decrease significantly, exhibiting quasi cleavage fracture. When the heating temperature is lower than the tempering temperature and after holding for 2 h, the impact properties of the weld seam and HAZ are significantly improved, showing ductile fracture. When the heating temperature is 30 ℃ lower than the tempering temperature, the holding time has a small impact on impact properties of the HAZ. However, an excessive holding time (8 h) will significantly reduce the impact properties of weld seam, so the holding time should not exceed 4 h. There are hardening and softening zones in the HAZ of welded joint, after heat treatment, the hardening effect is eliminated but the softening effect is slightly aggravated. The microstructure of weld seam after post-weld heat treatment is mainly composed of acicular ferrite and granular bainite. With the increase of heating temperature or the prolongation of holding time, obvious carbides precipitate at the grain boundaries, and the average size of acicular ferrite increases.

Key words: Q690D steel, post-weld heat treatment, butt joint, microstructure, mechanical properties

中图分类号:

TG156
TG407

李争, 张赫, 王飘扬, 付文俊, 徐玉君. 焊后热处理对Q690D钢对接接头组织和性能的影响[J]. 金属热处理, 2025, 50(5): 208-213.

Li Zheng, Zhang He, Wang Piaoyang, Fu Wenjun, Xu Yujun. Effect of PWHT on microstructure and properties of Q690D steel butt joints[J]. Heat Treatment of Metals, 2025, 50(5): 208-213.

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