本文選題：DP超高強鋼 + 激光焊接　； 參考：《天津大學學報(自然科學與工程技術版)》2017年03期

【摘要】：利用Nd:YAG固體激光器對DP980超高強鋼進行激光對接焊接,通過硬度測試、拉伸試驗研究DP980超高強鋼激光焊接接頭力學性能的變化,采用光學顯微鏡(OM)、掃描電子顯微鏡(SEM)等觀察顯微組織的轉變.結果表明:DP980超高強鋼經過激光焊接,焊接接頭分為焊縫金屬區(qū)、完全相變區(qū)、不完全相變區(qū)、回火區(qū)和母材區(qū).焊后焊縫金屬區(qū)和完全相變區(qū)為馬氏體組織,硬度較高;焊接接頭軟化現(xiàn)象發(fā)生在不完全相變區(qū)和回火區(qū):不完全相變區(qū)馬氏體發(fā)生相變使得鐵素體含量增加;回火區(qū)組織發(fā)生回火,馬氏體析出碳化物,導致軟化.在力學性能方面,焊接接頭抗拉強度略有降低,延伸率下降明顯,軟化區(qū)的存在導致在拉伸試驗時焊接接頭的不均勻變形,造成了其塑性明顯下降;拉伸試樣的斷裂發(fā)生在焊接接頭熱影響區(qū),斷口觀察發(fā)現(xiàn)存在有大小不等、深淺不一的韌窩,屬于塑性斷裂.
[Abstract]:Laser butt welding of DP980 ultra-high strength steel was carried out by using Nd:YAG solid-state laser. The mechanical properties of laser welded joint of DP980 ultra-high strength steel were studied by hardness test and tensile test.Optical microscope and scanning electron microscope (SEM) were used to observe the transformation of microstructure.The results show that the welded joints are divided into weld metal zone, complete phase transition zone, incomplete phase transition zone, tempering zone and base metal zone.After welding, the weld metal zone and complete transformation zone are martensite structure with high hardness, and the softening of welded joint occurs in incomplete transformation zone and tempering zone: martensite transformation in incomplete transformation zone makes the content of ferrite increase.Tempering occurs in the tempering zone and martensite precipitates carbides leading to softening.In terms of mechanical properties, the tensile strength and elongation of welded joints decreased slightly, and the existence of softening zone resulted in uneven deformation of welded joints during tensile tests, which resulted in a marked decrease in plasticity.The fracture of tensile specimen occurs in the heat-affected zone of welded joint, and the fracture surface observation shows that there are dimples of varying size and depth, which belong to plastic fracture.
【作者單位】： 天津大學材料科學與工程學院;湖北汽車工業(yè)學院材料科學與工程學院;
【基金】：國家自然科學基金資助項目(51175374) 先進焊接與連接國家重點實驗室開放基金資助項目(AWJ-Z15-03)~~
【分類號】：TG456.7

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本文編號：1745564