补焊次数对A6N01S-T5铝合金对接接头微观组织与力学性能的影响

对A6N01S-T5铝合金进行一次焊接和三次补焊试验,系统分析补焊次数对接头微观组织和力学性能的影响。结果表明,焊缝区由α-Al以及(α-Al+Mg_2Si)的伪共晶组织构成;随着补焊次数的增加,焊缝区组织变化不大,热影响区产生过时效现象形成软化区。焊缝区显微硬度高于热影响区,且随补焊次数的增加热影响区范围增大,显微硬度值下降;这主要与热影响区过时效现象加剧有关。补焊对焊接接头抗拉强度和弯曲性能影响较小,而对延伸率影响较大;随着补焊次数的增加,延伸率不断下降。拉伸试样均断裂于热影响区,为接头力学性能的薄弱部分。     

自动化列车用6005A-T6铝合金焊接接头的微观组织与力学性能

以厚度为35 mm的6005A-T6铝合金为试验材料,进行单、双面FSW对接焊接试验,研究焊缝的微观组织与力学性能。结果表明,单、双面FSW焊缝前进侧与母材有明显的界面,双面焊焊核区的晶粒更加细小,双面焊焊缝的力学性能和耐腐蚀性能更好。     

6082铝合金MIG焊焊接接头组织与力学性能研究

通过拉伸、弯曲、硬度试验以及金相分析等对6082铝合金MIG焊接头的力学性能与显微组织进行了研究。结果表明:采用5087焊丝焊接6082铝合金时,具有较好的抗拉性能,板厚8和4mm的焊接接头焊态的抗拉强度分别为母材的77.8%和73%;弯曲断裂集中在熔合线处,弯曲角度均较小;6082铝合金MIG焊接头焊缝中心组织为等轴晶,靠熔合线的焊缝晶粒沿散热方向呈柱状晶,熔合区晶粒粗大;软化区出现过时效效应,使Mg2Si长大,成为接头最薄弱的区域。     

厚板铝合金搅拌摩擦焊接头不同状态微观组织与力学性能

对14 mm厚2219～O铝合金板进行了搅拌摩擦焊接,研究了无缺陷、有缺陷和经焊后热处理的接头分层切片的微观组织、力学性能和断裂方式.结果表明:无缺陷接头的抗拉强度σb和屈服强度σMM0.2分别从上部的160.8和96.8 MPa下降至底部的146和86 MPa;有缺陷接头的σb和σ0.2分别从上部的132.9和94 MPa下降至底部的126和78.8 MPa;经焊后热处理的试样中部的σb最高,达到243.8 MPa,而上部的σ0.2最高,为123.3 MPa;延伸率δ则依次升高,无缺陷,有缺陷和热处理后接头的δ分别由上部的6.7%,4.8%和7.5%升高至底部的10.1%,8.5%和14%.经焊后热处理的接头焊核区晶粒沿厚度方向更均匀和细小,力学性能明显提高,并以韧性断裂为主,显微硬度波动很小.对于有缺陷接头,焊接缺陷严重降低了接头的力学性能,主要以韧-脆混合方式断裂,各分层的显微硬度均低于无缺陷接头.     

热矫形温度对6N01铝合金接头组织与性能的影响

对6N01-T5铝合金焊接接头进行了不同温度的热矫形,研究了矫形温度对接头微观组织及力学性能的影响规律。结果表明,250℃内加热时接头强度和焊缝区硬度有微量上升,HAZ和母材区硬度逐渐变大;高于250℃时强度和硬度开始下降,软化区范围加宽,分别向母材和淬火区方向延伸,高温下性能恶化严重;150℃~200℃加热时易发生弯断,且弯断角随温度升高而减小。室温时,接头母材区析出相为GP区和β″,硬度值较低,热影响区软化区晶内在只有粗大析出相;250℃加热时,母材区开始析出β′相,在β″和β'的析出转变期接头硬度与强度出现峰值,软化区因重新析出β'/β″相得到强化,拉伸断于焊缝;450℃加热时,接头处于严重过时效状态,无弥散析出相,硬度和强度降低。     

高速列车用6N01铝合金焊接接头的组织与性能

采用钨极氩弧焊(TIG)方法对6N01铝合金进行焊接,对焊接接头的微观组织、力学性能进行了研究.结果表明,6N01铝合金焊接性能较好,焊接接头的强度为186.7 MPa,可达到母材强度的65.6%.在焊接热循环的作用下,焊接接头的力学性能相对于基材发生了较大的变化,焊接热影响区内的软化区是合金接头的最薄弱环节,拉伸试验时在该处发生断裂,其次是焊缝处.     

高速列车用高强A7N01铝合金焊接接头的组织与性能

通过维氏硬度计、扫描电镜、能谱仪对高速列车用A7N01铝合金MIG焊接接头的显微硬度、微观组织、疲劳断口形貌及组织成分进行试验分析。结果表明,焊接接头热影响区淬火区晶粒细小,晶内有很多细小的强化相;软化区晶粒粗大,晶内细小强化相较少,强化相在晶界处聚集长大。热影响区晶内有很多粗大化合物Al8Fe2Si,这些粗大化合物中杂质元素Fe、Si含量较高,容易导致疲劳裂纹的萌生。在粗大化合物的边界部位有强化相MgZn2析出。焊接接头硬度分布不均匀,软化区硬度明显低于淬火区,焊缝硬度最低,为72.1 HV,母材硬度最高,为135 HV。疲劳模拟试验表明,在靠近熔合线的热影响区产生了疲劳裂纹,并在淬火区扩展至试样最终断裂。疲劳裂纹倾向于沿晶扩展,疲劳断口上有很多沿晶二次裂纹。     

焊接速度对5754铝合金FSW接头微观组织和力学性能的影响

对3 mm厚的5754铝合金板材进行搅拌摩擦焊接，研究了搅拌头在转速800 r/min条件下，不同焊接速度(100 ~ 400 mm/min)对搅拌摩擦焊接头微观组织和力学性能的影响. 结果表明，5754铝合金FSW接头横截面形貌呈“盆”形. 随着焊接速度增加，5754铝合金FSW接头的焊核区和轴肩区的面积逐渐减小，而搅拌针区面积先增加后减小. 当焊接速度为300 mm/min时，搅拌针区面积达到最大值6.66 mm2，轴肩区和搅拌针区面积比例为0.97，5754铝合金FSW接头的强度系数达到97.5%，这主要是因为轴肩区和搅拌针区面积相近，增大了焊核区和热影响区界面面积，从而提高了FSW接头强度，拉伸断裂在焊核区以外(热影响区或基材区)，断口为韧性断口. 当焊接速度为400 mm/min时，5754铝合金FSW接头的强度系数为58.8%，拉伸试样均断裂在焊核区，断口为脆性断口.     

ER 5356铝合金焊丝焊接接头组织及力学性能

通过拉伸、弯曲、硬度试验和金相分析等,对ER 5356铝合金焊接接头的组织与力学性能进行了研究,并对断口进行了SEM扫描分析,结果表明：ER 5356铝合金焊丝焊接接头的拉伸性能和抗弯性能均符合要求;焊缝区显微组织主要为α（Al）相基体和其上分布的部分析出β（Mg₂Si）相,焊缝晶粒形态为等轴树枝晶,焊缝中心最后冷却,焊缝中部冷却较慢为等轴晶粒,晶粒均匀细小;热影响区的焊接温度超过了原有的时效温度,但又未达到固溶温度。出现了过时效效应,从而产生了过析出的软化区。     

铝合金搅拌摩擦焊异种焊接头的显微组织和力学性能

对8mm厚6082/5083铝合金进行了搅拌摩擦焊焊接,焊后通过金相分析、拉伸试验和断口形貌观察等方法研究了搅拌摩擦焊异种焊接头的显微组织和力学性能.研究结果表明:在旋转速度800 r/min、焊接速度120 mm/min工艺条件下,接头表面成形良好,内部无明显缺陷.焊核区是由细小的等轴晶组织构成;前进边和回转边的界面形态差异较为明显,前进边的组织形貌呈花纹状,由两种铝合金组织交互融合而成,但回转边组织形貌则呈曲线状,明显将两种组织分开.断口形貌分析显示,接头断裂模式为脆性断裂.     

5083铝合金搅拌摩擦焊接头的微观组织与力学性能

通过金相分析、拉伸及断口形貌观察等方法研究8 mm厚5083铝合金搅拌摩擦焊接头的显微组织和力学性能.金相观察结果表明:焊核区由细小的等轴晶组织构成;热机影响区受机械和热的双重作用组织发生了较大程度的变形;热影响区仅受热循环的作用,与母材组织相似,但组织稍微有粗化现象.力学试验表明:焊接速度为160 mm/min时,接...     

不同焊丝对A7N01铝合金焊接接头力学性能的影响

采用ER5356、ER5183和ER5087焊丝对A7N01S-T5铝合金进行MIG焊接,分析接头力学性能。试验结果表明,三种焊丝的接头焊接残余应力大小基本相当;采用ER5183焊丝焊接的接头抗拉强度和断后伸长率最高,且弯曲性能良好,原因是接头内气孔量较少;采用ER5356焊丝焊接的接头焊缝和热影响区的冲击功最高,ER5087焊丝接头焊缝和热影响区冲击功则低得多。综合来看,ER5183焊丝与A7N01S-T5铝合金的匹配性更好。     

A6N01铝合金脉冲MIG焊接接头的组织与性能研究

采用脉冲熔化极惰性气体保护焊(P-MIG)方法进行了国产A6N01铝合金的焊接,研究了焊接接头的力学性能和微观组织等,结果表明:焊缝熔敷金属为等轴晶状的铸态组织,靠近母材的熔合区形成了一层较薄的细小等轴状组织,焊接热影响区的部分强化相Mg2Si固溶到基体中。焊接接头的显微硬度以焊缝中心最低。焊接接头成形良好,焊态抗拉强度为198 MPa,断后伸长率为7.0%,断口位于焊缝。     

Al-Cu-Li合金搅拌摩擦焊接头的微观组织和力学性能

采用搅拌摩擦焊方法对2mm厚的Al-Cu-Li合金轧制板进行了焊接.接头内形成了焊核区、热机影响区和热影响区.焊核区由细等轴再结晶组织构成;热机影响区内的组织发生较大的弯曲变形,并在热循环的作用下发生了回复反应;热影响区形成了粗大的板条状组织.实验结果表明:在200mm/min的焊接速度下,接头的拉伸强度最高,达到393MPa,断裂形式为韧性和脆性的混合型断裂;在500mm/min的焊接速度下,接头强度为267.7MPa,断裂形式为脆性断裂.     

Evolution of residual stress field in 6N01 aluminum alloy friction stir welding joint

Based on the characteristics of friction stir welding( FSW) and Coulomb friction work theory,the residual stresses field of FSW joints of 6 N01 aluminum alloy( T5),which was used in high speed train,were calculated by using the ANSYS finite element software. During the FEM calculation,the dual heat source models namely the body heat source and surface heat source were used to explore the evolution law of the welding process to the residual stress field. The method of ultrasonic residual stress detecting was used to investigate the residual stresses field of the 6 N01 aluminum alloy FSW joints. The results show that the steady-state temperature of 6 N01 aluminum alloy during FSW is about 550 ℃,and the temperature mutates at the beginning and at end of welding. The longitudinal residual stress σ_x is the main stress,which fluctuates in the range of-25 to 242 MPa. Moreover,the stress in the range of shaft shoulder is tensile stress that the maximum tensile stress is 242 MPa,and the stress in the outside of shaft shoulder is compressive stress that the maximum compressive stress is 25 MPa. The distribution of the tensile stress in the welding nugget zone( WNZ) is obviously bimodal,and the residual stress on the advancing side is higher than that on the retreating side. With the increasing of the welding speed,the maximum temperature decreased and the maximum residual stress decreased when the pin-wheel speed kept constant. With the increasing of the pin-wheel speed,the maximum temperature of the joint increased and the maximum residual stress increased when the welding speed was constant. The experimental results were in good agreement with the finite element results.     

7N01铝合金脉冲MIG焊接头组织与力学性能分析

采用脉冲MIG焊接方法分四层焊接12 mm厚7N01铝合金板材,研究了焊接接头的显微组织与力学性能。显微组织结果表明,从盖面层依次到打底层焊道受热循环次数逐渐增加,焊缝组织晶粒越来越粗大,并有明显的交界线;部分熔化区越来越宽,晶粒重熔也逐渐严重。力学性能结果表明,焊缝区硬度明显低于母材硬度,焊接接头的抗拉强度达到312 MPa,断后延伸率9.7%,断裂位置均位于焊缝;焊缝区低温冲击韧性32.5 J/cm2,热影响区低温冲击韧性37.2 J/cm2。试验表明,7N01铝合金采用脉冲MIG焊接方法焊接性能良好。     

Laser-pulsed MIG hybrid welding technology of A6N01S aluminum alloy

Welding research of A6N01S-T5 aluminum alloy profile for high-speed train was done by using laser-MIG hybrid welding and MIG welding individually. And the weld appearance,welding distortion,mechanical properties of the joints and microstructures were analyzed. The test results demonstrated that high-efficient welding for the profile can be achieved by using laser-MIG hybrid welding,the speed of which can be over 3. 0 m/min. The processing had a good gap bridging ability,even if the gap of the butt joint was up to 2. 0 mm,a good weld appearance can also be got. While the hybrid welding speed was greater than 2. 5 m/min,the welding distortion of the laser-tandem MIG hybrid joints was just about 33% of that of the MIG joints,but the welding efficiency was over 3 times of MIG welding. And tensile strength of the hybrid joints was 85% of that of A6N01S-T5 base metal,9% higher than that of the MIG joints. Fatigue properties was tested individually with pulsed tensile fatigue method in the condition of 1 × 10~7 lifetime. The test results demonstrated that the fatigue strength of the joints was a little lower than that of base material,which could be up to 115 MPa. But the fatigue strength of hybrid welding joints was 107. 5 MPa,which was 23% higher than 87 MPa of MIG welding joints.     

7N01铝合金搅拌摩擦焊接头力学性能

研究了在不同焊接参数的条件下,7N01铝合金搅拌摩擦焊接头的力学性能.结果表明,在特定的旋转频率和前进速度匹配条件下,下压量在0.3～1.0 mm范围波动,7N01铝合金搅拌摩擦焊接头的抗拉强度均能够稳定在340 MPa以上,达到母材的80%左右.通过扫描电镜观察断口发现,搅拌摩擦焊接头断口以韧窝型为主,在低倍下部分断口呈现出明显的分层现象,两层间分界部分呈现出阶梯状形貌.接头硬度测试表明,后退侧的平均硬度略高于前进侧,这也与拉伸测试中接头普遍断于前进侧的现象吻合.     

Effect of weld reinforcement on fatigue properties of A6N01 aluminum alloy welded joint

Fatigue properties of smooth and reinforcement A6N01 aluminum alloy welded joints were characterized in this paper. Based on measured S-lgN curves and fatigue fracture morphologies, effect of weld reinforcement on the fatigue property of the welded joint was studied. Results show that the weld toe is the weakness region of the reinforcement welded joint due to the stress concentration in this area, thus the fatigue fracture occurred at the weld toe for all the reinforcement welded joints; while the fatigue property of the smooth welded joint was improved due to remove of the weld reinforcement, and the welding defect was the key factor of the fatigue fracture, thus its fracture zones mainly located at welding zone and fusion line.