2219铝合金及变极性TIG焊焊接接头的力学性能

通过拉伸实验,借助光学显微镜和扫描电镜等手段,测定了2219—T62铝合金母材及变极性TIG焊焊接接头在不同温度下的力学性能,并且对母材以及焊接接头的断口形貌及微观组织进行了观察分析。实验结果表明,铝合金具有低温韧性增强现象,适用于低温工作条件;接头的抗拉性能及延伸率相比母材都有大幅下降。探讨了温度对母材及焊接接头性能的影响。     

热处理对铝合金气瓶焊接接头微观组织的影响

以6061铝合金为母材的铝合金气瓶作为研究对象,通过光学显微组织分析手段研究不同热处理制度对铝合金气瓶接头微观组织的影响.结果表明:焊后焊丝会与母材在填焊区和热影响区之间发生熔合,形成一层熔合界面.铝合金气瓶经过时效处理后,焊接接头熔合区的晶粒长大,Mg和Si进一步在晶界处析出;经过固溶与时效热处理后,熔合界面的析出相...     

薄板5A06铝合金VPPA焊缝的补焊性能

针对薄板铝合金穿孔型变极性等离子焊接可能产生的背面咬边、沟槽等缺陷,进行了手工TIG补焊,分析了3mm厚5A06铝合金补焊接头的拉伸性能。结果表明,采用手工方法补焊沟槽缺陷时,补焊接头强度比原始焊缝强度平均值有所降低;采用手工方法补焊等离子弧焊缝长距离咬边时,尽管咬边补焊加剧了强化相的偏析、晶粒的粗化,但是焊趾处经过重熔后,提升了接头整体强度值。     

Ti6Al4V厚板低匹配TIG窄间隙焊接头力学性能

本文针对800MPa级TI6AL4合金,选取低于母材强度级别的2B焊丝,并采用TIG窄间隙焊接,同时对接头的力学性能和显微组织分别进行了测试和观察。结果表明:采用TIG窄间隙焊的焊接接头抗拉强度为900MPa,接头延伸率为8%,通过SEM试验发现,窄间隙接头母材的合金元素向焊缝中心扩散,合金元素强化了焊接接头。     

5083铝合金搅拌摩擦焊接头组织及力学性能研究

采用搅拌摩擦焊焊接5083铝合金,光学显微镜OM、透射电镜TEM对焊接接头进行金相分析,拉伸试验和硬度试验对焊接接头力学性能进行分析。结果表明,焊接接头焊核区为晶粒细小的等轴晶组织,热力影响区晶粒细小且沿剪切方向拉长,热影响区晶粒明显长大。其接头的力学性能显著优于传统的熔化焊,抗拉强度约为母材的90%,塑性与母材相当;硬度分布均匀,可达母材的90%。     

Ti_2AlNb基合金超音频直流脉冲TIG焊

分别采用20,40,50,60 kHz不同频率的4组超音频直流脉冲TIG焊工艺焊接了厚度为1.5 mm的Ti2AlNb基合金板材。并采用X射线探伤手段对焊缝中的气孔缺陷进行检测,比如气孔的数量、尺寸及分布的位置;对于无缺陷的接头,观察接头的宏观和显微组织,测试接头硬度分布规律和拉伸性能。结果表明:采用脉冲频率为40,50,60 kHz的超音频直流脉冲TIG焊工艺对Ti2AlNb基合金进行焊接时,焊缝中气孔数量明显减少,尺寸减小,分布也由接头的内部变为接近表面的位置,在50,60 kHz的频率下能够得到没有气孔缺陷的焊接接头;接头各区域相组成不同,除B2基体以外,随母材向热影响区(HAZ)和熔合区(FZ)过渡,O相含量逐渐减少;由于相组成的变化,焊接接头的硬度分布规律为热影响区的硬度最高,母材次之,熔合区最低;对于4种不同频率的焊接工艺,采用频率为50 kHz时焊接接头抗拉强度最高,可达到926.20 MPa,加焊丝后可以在一定程度上进一步优化焊接接头的抗拉性能,降低同一焊接工艺下试样的性能分散性。     

7075航空铝合金TIG焊后热处理对其接头力学性能的影响

以航空用7075铝合金为焊接母材,采用航空专用铝合金ER5056焊丝对其进行TIG焊接,将焊后接头进行固溶处理+时效处理,研究焊接电流为130 A条件下的接头在不同固溶温度与固溶时间、不同时效温度与时效时间下进行热处理,通过对接头的硬度、拉伸力学性能、断口形貌及能谱进行表征发现,当固溶温度与时间为470℃×2 h、时效温度与时间为120℃×24 h条件下得到的接头具有较好的综合力学性能。     

电子束焊喷射成形Al-Zn-Mg-Cu合金的组织性能研究

采用电子束焊接的方法对10 mm厚的喷射成形Al-Zn-Mg-Cu合金板进行了拼焊实验。采用金相显微镜、扫描电镜、室温拉伸实验、显微硬度等方法分析了焊接接头的微观组织,测试了焊接接头的力学性能及显微硬度。结果表明,喷射成形Al-Zn-Mg-Cu合金焊接接头由三个区域(近缝区母材,焊核区,热影响区)组成。焊缝宽为0.3～1.0 mm,焊核区由尺寸约3～8μm的等轴细晶组成,析出相沿晶界分布,晶内析出相较少;热影响区大部分保留了母材的原始组织特征,小部分区域发生了重熔。从焊缝区到母材,显微硬度值逐渐下降,焊缝区硬度值高出母材约35。经T6处理后,焊接接头强度约为母材的82%。     

铝合金/Q235钎剂涂层钢板异种金属CMT焊接分析

采用CMT(Cold Mental Transfer,冷金属过渡焊)焊接技术,分别对5083铝合金和6061铝合金与Q235钎剂涂层钢板进行焊接实验。采用NOCLOCK+30%Zn粉的钎剂配方和相同的焊接工艺参数,对焊缝界面组织的SEM和EDS观察分析,研究不同母材对铝合金/钢异种金属焊接的影响。结果表明:采用该钎剂配方可以基本满足铝合金/钢异种金属焊接的要求;铝母材中镁含量越高,得到的接头性能越差。     

轨道交通用7xxx系铝合金接头组织性能浅析

对轨道车体用7xxx铝合金接头进行MIG对接焊,填充金属选用直径为1.2mm的ER 5087铝合金焊丝,焊后对焊接接头进行拉伸,微观金相组织观测及显微硬度测试,目的在研究轨道车体用7xxx铝合金接头的组织和性能。研究结果显示,7N01铝合金焊接接头实际强度系数大于0.6,接头硬度最低值位于焊缝中心,热影响区硬度较母材略有降低;焊缝区由等轴晶及粗大柱状晶组成,熔合线处存在垂直熔合线的等轴晶;焊接接头后主要强化相为MgZn₂,同时存在一定数量呈条状分布的第二相粒子Mg₂Si。     

CO2 laser beam welding of 6061-T6 aluminum alloy thin plate

Laser beam welding is an attractive welding process for age-hardened aluminum alloys, because its low heat input minimizes the width of weld fusion and heat-affected zones (HAZs). In the present work, 1-mm-thick age-hardened Al-Mg-Si alloy, 6061-T6, plates were welded with full penetration using a 2.5-kW CO₂ laser. Fractions of porosity in the fusion zones were less than 0.05 pct in bead-on-plate welding and less than 0.2 pct in butt welding with polishing the groove surface before welding. The width of a softened region in the-laser beam welds was less than 1/4 times that of a tungsten inert gas (TIG) weld. The softened region is caused by reversion of strengthening β″ (Mg₂Si) precipitates due to weld heat input. The hardness values of the softened region in the laser beam welds were almost fully recovered to that of the base metal after an artificial aging treatment at 448 K for 28.8 ks without solution annealing, whereas those in the TIG weld were not recovered in a partly reverted region. Both the bead-on-plate weld and the butt weld after the postweld artificial aging treatment had almost equivalent tensile strengths to that of the base plate.     

Friction stir welding of magnesium alloy ZM21

Friction stir butt welding of Mg-Zn-Mn alloy ZM21 hot rolled plates (in three thicknesses — 5 mm, 10 mm and 25 mm) was investigated. Defect-free, full-penetration welds were produced after careful process parameter optimization. Microstructural studies, hardness tests, tensile tests, and bend tests were carried out. Welds produced in 5 mm thick (5-mm-welds) and 10 mm thick plates (10-mm-welds) showed relatively finer grains in the weld nugget and in the heat-affected zone compared to the welds produced in 25 mm thick plates (25-mm-welds). When compared to the base material, 25-mm-welds showed coarser grains both in the weld nugget and in the heat-affected zone. No significant hardness differences were observed between the welds and the base material. Tensile tests on 5-mm and 10-mm-welds yielded a joint efficiency of more than 75%. Bend performance of the welds was found to be satisfactory, falling only slightly behind the base material. Overall, the results show that friction stir welding can be successfully utilized for joining magnesium alloy ZM21 in various thicknesses.     

Quantitative evaluation of softened regions in weld heat-affected zones of 6061-T6 aluminum alloy—Characterizing of the laser beam welding process

In welding 6061-T6 aluminum alloy, softening caused by the dissolution of strengthening β″ (Mg₂Si) precipitates occurs in heat-affected zones (HAZs). Laser beam welding is advantageous in view of narrower softened regions. The width of the softened region in a laser beam weld with a welding speed of 133 mm/s is 1/7 that of a tungsten inert gas (TIG) weld with a speed of 5 mm/s. The hardness distributions and width of softened regions in the HAZ have been quantitatively predicted to characterize the laser beam welding process. To this end, a kinetic equation describing the dissolution of age precipitates has been established and has been applied to 6061-T6 aluminum weldments. The hardness profiles and the width of softened zones have been successfully predicted in both welding processes. Prediction of the width of softened regions with varying power inputs and welding speeds reveals that a high energy density and a high welding speed in laser beam welding result in significantly narrower softened regions, in which the width is insensitive to variations in welding parameters compared to that of TIG welding.     

Characterization of a friction-stir-welded aluminum alloy 6013

The aluminum alloy 6013 was friction-stir welded in the T4 and the T6 temper, and the microstructure and mechanical properties were studied after welding and after applying a postweld heat treatment (PWHT) to the T4 condition. Optical microscopy (OM), transmission electron microscopy (TEM), and texture measurements revealed that the elongated pancake microstructure of the base material (BM) was transformed into a dynamically recrystallized microstructure of considerably smaller grain size in the weld nugget. Strengthening precipitates, present before welding in the T6 state, were dissolved during welding in the nugget, while an overaged state with much larger precipitate size was established in the heat-affected zone (HAZ). Microhardness measurements and tensile tests showed that the HAZ is the weakest region of the weld. The welded sheet exhibited reduced strength and ductility as compared to the BM. A PWHT restored some of the strength to the as-welded condition.     

含铝304和316L奥氏体不锈钢热轧板材焊接性能

 对加Al质量分数为4%的304、2%的316L不锈钢热轧板材的焊接性能进行了研究。采用手工氩弧焊（TIG）的焊接方法,利用光学显微镜对焊缝的显微组织进行分析,利用电子探针（EMPA）分析焊接母材的元素分布,并对焊接接头进行力学性能测试。组织和力学性能的研究结果表明：含铝304和含铝316L合金热轧板分别选用ER308L,ER316L作为焊接材料,经TIG焊接后,焊缝无裂纹、气孔等缺陷,接头具有良好的强度和塑性,焊接接头力学性能接近于其母材;热影响区组织与母材组织基本一致,焊缝与母材熔合良好,组织良好,加铝304和316L不锈钢具有良好的焊接性能。     

不同5xxx系焊丝对5182-H111组织和性能的影响

使用3种焊丝ER 5183、ER 5356、ER 5554对6mm 5182-H111铝合金板材进行半自动MIG焊对接试验,通过对焊接接头进行力学性能试验、显微硬度测试及金相组织的观察,探究3种焊丝对5182-H111铝合金组织和性能的影响。结果表明,使用3种焊丝所焊接头中,ER 5183及ER 5356接头抗拉强度均大于ISO 15614-22005要求的焊缝接头系数(1.0),而ER 5554接头焊缝系数仅为0.949;3种焊丝所焊接头硬度均在焊缝区及热影响区有所降低,其中ER 5356所焊接头焊缝强度较其他两种焊丝焊缝区硬度高,为85.5HV;3种焊丝所焊接头组织形貌相近,均存在β(Mg2Al3)强化相,但由于ER 5183与ER 5356焊丝中含有更多的Mg,因此生成了更多的β(Mg2Al3)相,使得焊缝组织更加致密。     

7003铝合金TIG焊焊接接头的组织与性能

采用显微硬度及电导率测试,剥落腐蚀及电化学腐蚀试验,光学显微镜(OM)及透射电镜(TEM),研究经ER5356焊丝钨极氩弧焊(TIG)的7003铝合金型材焊接接头各部分的微观组织与性能。结果表明:在离焊缝中心30 mm左右的热影响区位置形成硬度较低的软化区,这是由于η′(Mg Zn2)相的长大粗化;焊接接头的耐蚀性依次为焊缝区过时效区母材区淬火区,其原因是淬火区的晶界析出相连续分布,形成连续阳极腐蚀通道,增大了应力腐蚀及剥落腐蚀倾向,使得腐蚀性能很差;而过时效区和母材区的晶界析出相不连续,耐蚀性较好。     

TIG焊接热循环对AZ31B镁合金硬度的影响

以AZ31B镁合金为研究对象，采用TIG焊方法进行焊接，考察了焊接热循环对镁合金的硬度的影响。测量、比较、分析了焊缝、热影响区、母材的硬度。结果表明，表面处理过程（研磨、抛光、侵蚀液体及工艺等）对镁合金硬度的影响很大，直接影响到“焊接工艺-硬度”之间关系。与母材相比，由于焊缝的冷却速率高，组织细小，硬度较高。热影响区的组织虽比母材粗大，但硬度与母材相近。焊缝区不同部位的硬度存在一定差异。     

Process Optimization for Friction-Stir-Welded Martensitic Steel

Advanced high-strength M190 steel sheets were joined by friction-stir welding under different tool rotational and traversing speeds. The optical microstructure of the joints exhibited complete martensite and partial martensite at the weld nugget depending on the cooling rate during welding. The first heat-affected zone outside of the weld nugget revealed ferrite-pearlite phase aggregate, and the second heat-affected zone showed a tempered martensitic structure. The interplay of process variables in terms of peak temperature and cooling rate was studied to observe their effect on joint efficiency under shear testing. The peak hardness at weld nugget was close to the parent alloy at an intermediate cooling rate of 294 to 313 K/s. The lowest hardness was observed at the first heat-affected zone for all welded joints. Joint efficiency was dependent on relative quantity of ferrite-pearlite at first heat-affected zone. In that respect, the intermediate temperature to the tune of ~1193 K to 1273 K (~920 °C to 1000 °C) at the weld nugget was found to be beneficial for obtaining an adequate quantity of pearlite at the first heat-affected zone to provide joint efficiency of more than 50 pct of that of parent alloy.     

Relationship Between Microstructure,Strength, and Fracture in an Al-Zn-Mg Electron Beam Weld: Part I: Microstructure Characterization

This work presents a detailed, multiscale, spatially resolved study of the microstructure of an electron beam butt weld of the EN-AW 7020 (Al-Zn-Mg) alloy. Using a combination of optical, scanning and transmission electron microscopy, differential scanning calorimetry, and small-angle X-ray scattering, the distribution of phases in the different areas of the heat-affected zone and of the fusion zone is quantitatively characterized, for two different aging states: naturally aged after welding and artificially aged at 423 K (150 °C). The heat-affected zone consists of regions experiencing different levels of precipitate dissolution and coarsening during welding as well as new precipitation during post-welding heat treatment (PWHT). The microstructure of the fusion zone is typical from a fast solidification process, with a strong solute segregation in the interdendritic zones. The precipitate distribution after PWHT follows this solute distribution, and the resulting hardness is much lower than the relatively homogeneous value in the base metal and the heat-affected zone.