【摘要】：本文以6mm厚高強(qiáng)鋼為實(shí)驗(yàn)材料,利用激光-電弧復(fù)合焊進(jìn)行焊接。為獲得強(qiáng)韌性均較好的復(fù)合焊接接頭,本試驗(yàn)設(shè)計(jì)了多種焊后熱處理方案,并對(duì)未熱處理和熱處理后接頭的組織、強(qiáng)度和韌性進(jìn)行了分析。為研究退火對(duì)強(qiáng)韌化的影響,設(shè)計(jì)了兩種不同工藝的退火熱處理。試驗(yàn)結(jié)果表明不同退火工藝后焊縫的硬度和強(qiáng)度均比未熱處理的低,但塑性得到改善。退火對(duì)原熱影響區(qū)的韌性提高較大。等溫退火使接頭整體韌性降低,兩種退火熱處理均未達(dá)到強(qiáng)韌化的目的。為研究正火對(duì)強(qiáng)韌化的影響,設(shè)計(jì)了兩種不同工藝的正火熱處理。試驗(yàn)結(jié)果表明正火后接頭硬度比未熱處理接頭的低,且分布不均勻,強(qiáng)度較高,塑性較差,韌性較低但均勻性良好。正火加高溫回火降低了接頭整體的強(qiáng)度以及焊縫的韌性,但塑性和原熱影響區(qū)的韌性得到有效提高,兩種正火熱處理的強(qiáng)韌化效果不理想。為研究回火對(duì)強(qiáng)韌化的影響,設(shè)計(jì)了11種不同溫度的回火熱處理。試驗(yàn)結(jié)果表明低溫回火后接頭硬度較高,當(dāng)溫度提高到250℃時(shí),母材區(qū)域硬度降低,隨著回火溫度的提高使焊縫的韌性降低,原熱影響區(qū)韌性呈先增長(zhǎng)后降低的趨勢(shì),韌性較小。中溫回火后硬度比未熱處理的低但分布均勻,當(dāng)回火溫度提高到450℃時(shí),硬度再次升高,提高回火溫度使焊縫的韌性比未熱處理焊縫的低,原熱影響區(qū)的韌性明顯增長(zhǎng),韌性較好。高溫回火后硬度逼近未熱處理的,均勻性較好,當(dāng)≥600℃時(shí),母材區(qū)域硬度下降嚴(yán)重。隨著回火溫度的提高,接頭的強(qiáng)度逐漸降低,塑性逐漸提高,高溫回火后焊縫和原熱影響區(qū)的韌性均較好。試驗(yàn)結(jié)果表明,550℃高溫回火時(shí),接頭的強(qiáng)韌性較好,達(dá)到強(qiáng)韌化目的。
[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，

本文編號(hào)：2198451