高强钢激光—电弧复合焊接强韧化热处理研究

发布时间：2018-08-23 08:15

【摘要】：本文以6mm厚高强钢为实验材料,利用激光-电弧复合焊进行焊接。为获得强韧性均较好的复合焊接接头,本试验设计了多种焊后热处理方案,并对未热处理和热处理后接头的组织、强度和韧性进行了分析。为研究退火对强韧化的影响,设计了两种不同工艺的退火热处理。试验结果表明不同退火工艺后焊缝的硬度和强度均比未热处理的低,但塑性得到改善。退火对原热影响区的韧性提高较大。等温退火使接头整体韧性降低,两种退火热处理均未达到强韧化的目的。为研究正火对强韧化的影响,设计了两种不同工艺的正火热处理。试验结果表明正火后接头硬度比未热处理接头的低,且分布不均匀,强度较高,塑性较差,韧性较低但均匀性良好。正火加高温回火降低了接头整体的强度以及焊缝的韧性,但塑性和原热影响区的韧性得到有效提高,两种正火热处理的强韧化效果不理想。为研究回火对强韧化的影响,设计了11种不同温度的回火热处理。试验结果表明低温回火后接头硬度较高,当温度提高到250℃时,母材区域硬度降低,随着回火温度的提高使焊缝的韧性降低,原热影响区韧性呈先增长后降低的趋势,韧性较小。中温回火后硬度比未热处理的低但分布均匀,当回火温度提高到450℃时,硬度再次升高,提高回火温度使焊缝的韧性比未热处理焊缝的低,原热影响区的韧性明显增长,韧性较好。高温回火后硬度逼近未热处理的,均匀性较好,当≥600℃时,母材区域硬度下降严重。随着回火温度的提高,接头的强度逐渐降低,塑性逐渐提高,高温回火后焊缝和原热影响区的韧性均较好。试验结果表明,550℃高温回火时,接头的强韧性较好,达到强韧化目的。
[Abstract]:In this paper, 6mm thick and high strength steel is used as experimental material, laser-arc welding is used for welding. In order to obtain the composite welded joints with good strength and toughness, various post-weld heat treatment schemes were designed, and the microstructure, strength and toughness of the joints after heat treatment and non-heat treatment were analyzed. In order to study the effect of annealing on strengthening and toughening, two different annealing processes were designed. The results show that the hardness and strength of the weld after different annealing processes are lower than those without heat treatment, but the plasticity is improved. The toughness of the primary heat affected zone is greatly improved by annealing. The overall toughness of the joint was decreased by isothermal annealing. In order to study the effect of normalizing on strengthening and toughening, normalizing heat treatment of two different processes was designed. The experimental results show that the hardness of normalizing joints is lower than that of untreated joints, and the hardness is not uniform, the strength is higher, the plasticity is poor, the toughness is lower but the uniformity is good. Normalizing and tempering at high temperature reduced the overall strength of the joint and the toughness of the weld, but the ductility and the toughness of the original heat affected zone were improved effectively, and the strengthening and toughening effects of the two normalizing heat treatments were not ideal. In order to study the effect of tempering on strengthening and toughening, 11 kinds of tempering heat treatment at different temperatures were designed. The results show that the hardness of joint is higher after tempering at low temperature. When the temperature is raised to 250 鈩，

本文编号：2198451