采用激光-MIG复合焊对X80管线钢和X100管线钢进行焊接,研究了激光功率对复合焊接头的焊缝形貌、显微组织、硬度、强度和韧性的影响规律.结果表明,激光功率从2.0 k W增大至3.5 k W时,盖面焊缝熔宽和熔深增加,激光区熔深明显增加;激光区...采用激光-MIG复合焊对X80管线钢和X100管线钢进行焊接,研究了激光功率对复合焊接头的焊缝形貌、显微组织、硬度、强度和韧性的影响规律.结果表明,激光功率从2.0 k W增大至3.5 k W时,盖面焊缝熔宽和熔深增加,激光区熔深明显增加;激光区焊缝中AF含量增加、LB含量减少,X100侧粗晶热影响区和细晶热影响区中条状贝氏体含量减少,X80侧粗晶热影响区和细晶热影响区中准多边形铁素体含量增加.复合焊接头硬度分布并不对称,最高硬度出现在X100侧熔合区部位.复合焊接头的抗拉强度基本不随激光功率变化,拉伸试样断裂位置均为X80侧母材.随着激光功率增大,焊接接头最高硬度和韧性均下降.展开更多
油气管道往往服役于恶劣环境,其焊接接头面临着严重的腐蚀问题,存在较大安全隐患。激光-电弧复合焊焊接效率高、变形小,已成为管道施工焊接领域具有良好应用前景的焊接方法。针对不同激光功率下X80管线钢激光-MIG复合焊焊缝的耐腐蚀性...油气管道往往服役于恶劣环境,其焊接接头面临着严重的腐蚀问题,存在较大安全隐患。激光-电弧复合焊焊接效率高、变形小,已成为管道施工焊接领域具有良好应用前景的焊接方法。针对不同激光功率下X80管线钢激光-MIG复合焊焊缝的耐腐蚀性进行研究。分析焊接接头各区域显微组织分布,研究母材和不同激光功率下激光-MIG复合焊焊缝的极化曲线、交流阻抗谱和SEM表面腐蚀形貌,得到了激光功率对激光-MIG复合焊焊缝电化学腐蚀行为的影响规律。结果表明,激光-MIG复合焊焊缝的显微组织由针状铁素体、粒状贝氏体和先共析铁素体构成;随着激光功率的增加,粒状贝氏体数量减少,针状铁素体和先共析铁素体含量增加。母材和激光-MIG复合焊焊缝的极化曲线均无显著的钝化区,母材的腐蚀电流密度大于激光-MIG复合焊焊缝,电荷转移电阻小于激光-MIG复合焊焊缝。随着激光功率的增加,激光-MIG复合焊焊缝的耐腐蚀性先上升再下降,激光功率为3.0 k W时焊缝的耐腐蚀性最好。展开更多
The high-temperature tensile behavior of laser welded Ti-22Al-25Nb (at%) joints was investigated at 500,650,800,and 1 000 ℃.The temperatures for tensile tests were selected according to the phase transformation seque...The high-temperature tensile behavior of laser welded Ti-22Al-25Nb (at%) joints was investigated at 500,650,800,and 1 000 ℃.The temperatures for tensile tests were selected according to the phase transformation sequence of Ti2AlNb-based alloys.At temperatures lower than the B2+O phase field (500 ℃) and higher than the B2+O phase field (1 000 ℃),the joints fracture in the base metal in ductile fracture mode.By contrast,the joints exhibit obvious high-temperature brittleness in the B2+O phase field (650 °C and 800 ℃).Heat treatments were conducted with respect to the thermal history of tensile specimens.Intergranular microcracks along the grain boundary of B2 phase are found in the fusion zone after the heat treatments at 650 ℃ and 800 ℃.The high-temperature brittleness at 650 ℃ and 800 ℃ is attributed to the B2→O transformation along the grain boundary.The stress concentration caused by the volume change of B2→O transformation also contributes to the high-temperature brittleness of laser welded Ti-22Al-25Nb joints.展开更多
The y-groove Tekken test has been performed to evaluate the cold cracking susceptibility of X100 pipeline steel.The impact of preheating state on the microstructure,distribution of hardness,and the stress-strain state...The y-groove Tekken test has been performed to evaluate the cold cracking susceptibility of X100 pipeline steel.The impact of preheating state on the microstructure,distribution of hardness,and the stress-strain state in the welded joint was analyzed.The results show that X100 pipeline steel reveals a low susceptibility to cold cracking with cracking ratios below 20%.It is found that elevated preheating temperature leads to longer cooling time in the welded specimen and ultimately results in a lower cold cracking susceptibility.Preheating temperatures of up to 100℃ are favorable in decreasing the cold cracking susceptibility due to a relative fine microstructure and low M-A constituent amount in coarse grained heat affected zone,a low hardenability,and low-level residual stress and strain.However,excessive preheating temperatures of 150℃ and 200℃ lead to grain coarsening,higher M-A constituent amount,higher residual stress level and increasing strain level in the Tekken specimens.Preheating temperature above 150℃is not favorable for decreasing the cold cracking susceptibility of X100 steel.展开更多
文摘采用激光-MIG复合焊对X80管线钢和X100管线钢进行焊接,研究了激光功率对复合焊接头的焊缝形貌、显微组织、硬度、强度和韧性的影响规律.结果表明,激光功率从2.0 k W增大至3.5 k W时,盖面焊缝熔宽和熔深增加,激光区熔深明显增加;激光区焊缝中AF含量增加、LB含量减少,X100侧粗晶热影响区和细晶热影响区中条状贝氏体含量减少,X80侧粗晶热影响区和细晶热影响区中准多边形铁素体含量增加.复合焊接头硬度分布并不对称,最高硬度出现在X100侧熔合区部位.复合焊接头的抗拉强度基本不随激光功率变化,拉伸试样断裂位置均为X80侧母材.随着激光功率增大,焊接接头最高硬度和韧性均下降.
文摘油气管道往往服役于恶劣环境,其焊接接头面临着严重的腐蚀问题,存在较大安全隐患。激光-电弧复合焊焊接效率高、变形小,已成为管道施工焊接领域具有良好应用前景的焊接方法。针对不同激光功率下X80管线钢激光-MIG复合焊焊缝的耐腐蚀性进行研究。分析焊接接头各区域显微组织分布,研究母材和不同激光功率下激光-MIG复合焊焊缝的极化曲线、交流阻抗谱和SEM表面腐蚀形貌,得到了激光功率对激光-MIG复合焊焊缝电化学腐蚀行为的影响规律。结果表明,激光-MIG复合焊焊缝的显微组织由针状铁素体、粒状贝氏体和先共析铁素体构成;随着激光功率的增加,粒状贝氏体数量减少,针状铁素体和先共析铁素体含量增加。母材和激光-MIG复合焊焊缝的极化曲线均无显著的钝化区,母材的腐蚀电流密度大于激光-MIG复合焊焊缝,电荷转移电阻小于激光-MIG复合焊焊缝。随着激光功率的增加,激光-MIG复合焊焊缝的耐腐蚀性先上升再下降,激光功率为3.0 k W时焊缝的耐腐蚀性最好。
基金Funded by the National Natural Science Foundation of China(Nos.51804097 and 51879089)the Fundamental Research Funds for the Central Universities of China(No.B200202219)+2 种基金the Changzhou Sci&Tech Program(No.CJ20190049)the State Key Lab of Advanced Welding and JoiningHarbin Institute of Technology(No.AWJ-19M16)。
文摘The high-temperature tensile behavior of laser welded Ti-22Al-25Nb (at%) joints was investigated at 500,650,800,and 1 000 ℃.The temperatures for tensile tests were selected according to the phase transformation sequence of Ti2AlNb-based alloys.At temperatures lower than the B2+O phase field (500 ℃) and higher than the B2+O phase field (1 000 ℃),the joints fracture in the base metal in ductile fracture mode.By contrast,the joints exhibit obvious high-temperature brittleness in the B2+O phase field (650 °C and 800 ℃).Heat treatments were conducted with respect to the thermal history of tensile specimens.Intergranular microcracks along the grain boundary of B2 phase are found in the fusion zone after the heat treatments at 650 ℃ and 800 ℃.The high-temperature brittleness at 650 ℃ and 800 ℃ is attributed to the B2→O transformation along the grain boundary.The stress concentration caused by the volume change of B2→O transformation also contributes to the high-temperature brittleness of laser welded Ti-22Al-25Nb joints.
基金Project was supported by the National Natural Science Foundation of China (Grant No. 51804097)Fundamental Research Funds for the Central Universities (Grant No. 2017B17614).
文摘The y-groove Tekken test has been performed to evaluate the cold cracking susceptibility of X100 pipeline steel.The impact of preheating state on the microstructure,distribution of hardness,and the stress-strain state in the welded joint was analyzed.The results show that X100 pipeline steel reveals a low susceptibility to cold cracking with cracking ratios below 20%.It is found that elevated preheating temperature leads to longer cooling time in the welded specimen and ultimately results in a lower cold cracking susceptibility.Preheating temperatures of up to 100℃ are favorable in decreasing the cold cracking susceptibility due to a relative fine microstructure and low M-A constituent amount in coarse grained heat affected zone,a low hardenability,and low-level residual stress and strain.However,excessive preheating temperatures of 150℃ and 200℃ lead to grain coarsening,higher M-A constituent amount,higher residual stress level and increasing strain level in the Tekken specimens.Preheating temperature above 150℃is not favorable for decreasing the cold cracking susceptibility of X100 steel.
