Resistance Element Welding of 6061 Aluminum Alloy to Uncoated 22MnMoB Boron Steel

A novel resistance element welding technology was applied to join 6061 Al alloy and uncoated 22MnMoB boron steel. To conduct the resistance element welding process, a technological hole was drilled in the Al sheet into which a Q235 steel rivet was inserted. Resistance spot welding was carried out at the rivet. The mechanical properties, fracture morphology, nugget formation process, dynamic resistance, microstructure, and hardness distribution of the resistance element welding were investigated. Traditional resistance spot weld joints were also prepared for comparison. Resistance spot welding could barely join Al 6061 and boron steel, and had a maximum tensile shear force of less than 1000 N. Novel resistance element welding could join the metals reliably with a maximum tensile shear force of over 7000 N and a relatively high toughness. Nugget formed at the interface of rivet and steel acted as loading position, and IMC interlayer connected rivet and aluminum.     

Friction Interface Migration of Copper Alloy and Carbon Steel Dissimilar Metal Joints in Inertia Radial Friction Welding

The microstructure and mechanical properties of the copper and steel bimetallic welded joint were analyzed. Research results show there was a friction interface transferring phenomenon in inertia radial friction welding (IRFW). A secondary friction interface (SFI) appeared in welded joints of H90 copper brass/D60 steel rod. The SFI showed an abnormal transferring phenomenon. The formation mechanism of the SFI was analyzed under the condition of H90 copper/D60 steel dissimilar metals in IRFW. A new model and formation mechanism were issued and used to explain the unusual transferring phenomenon and characteristic in the views of three gradients: temperature gradient, deformability gradient (large or super plastic deformability), and microstructure gradients. The microhardness and element diffusion also supported our viewpoints about the SFI transferring and provided proofs for the transferring mechanism.     

Microstructural and Mechanical Observations of Galvanized TRIP Steel after Friction Stir Spot Welding

Friction stir spot welding was done in transformation-induced plasticity steel sheets coated with zinc. The influence of tool rotational speed and dwell time on the microstructure and mechanical properties of lap-joints were investigated. After processing, different zones were formed in the joints. Microstructures in each zone depended on the welding conditions employed. Higher dwell time coupled with higher rotational speed promoted the deposition of a large amount of allotriomorphic ferrite beside the keyhole left by the pin. Coalesced bainite formation was stimulated by the deformation. Mechanical and chemical stabilization of the austenite occurred in different welding zones. Some zinc from the coating remained in the joint, in the stirring zone, representing a partial bonding between the steel sheets. The strength of the welds depended on a complex interaction between geometrical features, such as bonding ligament length and distance between the zinc and the keyhole left by the pin and the resultant microstructure in the stirring zone. The highest joint strength was observed for the “lowest tool rotational speed–highest dwell time” combination of welding parameters.     

6063-T6铝合金管连续驱动摩擦焊接工艺

本文着重介绍了6063 -T6铝合金管连续驱动摩擦焊接工艺,以及6063 -T6铝合金管采用连续驱动摩擦焊接的结果及分析,表明只要选择合理的焊接工艺参数,在6063 -T6铝合金管批量生产中采用连续驱动摩擦焊接是可行的.     

Fabricating Defect-Free API X65 Steel Welds under Underwater Wet Conditions using Friction Taper Plug Welding

The experiment on API X65 steel was carried out using friction taper plug welding (FTPW) under underwater wet conditions at room temperature. Sound weld formation can be achieved vastly at axial force ranging from 25 to 40 kN and a rotating speed of 7000 rpm. The microstructure of the weld zone consists of lath martensite, upper bainite, granular bainite, polygonal ferrite, and acicular ferrite. The microstructure of heat affected zone (HAZ) mainly consists of lath bainite as well as a bit of lath martensite and granular bainite. The tensile properties of defect-free welds are excellent. The maximum impact energy of the V-notch of bonding area can reach 110 J, which was conducted at 0°C with an error of ±12.5 J. The typical SEM impact fracture morphology presents areas of cleavage, quasi-cleavage, and dimples.     

连铸10CrNiCu钢焊接预热温度的确定

通过间接估算和试验两种途径对连铸10CrNiCu钢板的焊接预热温度进行了研究,研究结果表明连铸10CrNiCu钢具有较好的焊接抗裂性,一般情况下焊接不需要预热,但是在低温高湿度、碳当量较高和结构拘束度大的情况下焊接时需要预热到60℃以上。     

浅谈铁路钢桥焊接工艺评定

通过铁路钢桥制造规范的学习,对钢桥焊接工艺评定工作的实施进行了理解和分析,介绍了焊接工艺评定实施的程序及要点,以及应注意的问题。     

数值模拟在超级钢焊接中的应用

本文综述了超级钢焊接温度场的数值模拟方法及研究现状,以及超级钢焊接热影响区微观组织的预测方法及研究现状,论述了超级钢的强化机制及细晶原理。超级钢作为一种性能好、成本低的新型材料,有着广阔的应用前景,但其焊接工艺尚不完善。数值模拟方法能够准确的模拟超级钢焊接温度场,预测超级钢焊接热影响区微观组织,这对了解超级钢焊接机理有很大帮助,并为优化焊接工艺提供指导和依据。     

TiAl金属间化合物研究现状及发展趋势

论述了ＴｉＡｌ金属间化合物在显微结构、蠕变、抗氧化等方面的研究成果及发展趋势。     

直接热处理细化铸态TiAl基合金的研究进展

直接热处理方法具有工艺简单、成本低廉、显微组织易于控制和适用性广等优点，是细化TiAl基合金铸件组织的重要方法之一，概括和总结了直接热处理方法在工艺和机理方面的研究进展，提出了直接热处理工艺存在的问题及解决的途径。     

TiAl基合金的超塑性力学性能

超塑性力学性能是合理制定超塑性成形工艺和正确选用模具材料的理论依据。总结了国内外在TiAl基合金超塑性研究中所获得的各种条件下的超塑性力学性能。内容包括应变速率敏感性因子、超塑性延伸率和典型的真应力-真应变关系。最后，对TiAl其合金超塑性成形的应用前景进行了展望。     

爆炸焊接不锈钢─钢复合板

通过改善爆炸焊接中、大面积、大厚度的不锈钢─钢复合板的工艺参数，对如何获得高质量的不锈钢─钢复合板作了深入探讨。各项金相、机械性能检验表明，方案具有较高的实用价值。     

日本潜艇用钢及焊接材料的焊接性能综述

本文综述了日本的潜艇用钢及其焊接材料的各项焊接性能试验情况。对NS63和NS80钢的大量试验结果表明:为了防止产生焊接裂纹,应根据钢种强度级别、板厚和拘束应力的不同来选择不同的预热和道间温度,通常在50~150℃之间变化;相应的焊接热输入也宜在16~24 kJ/cm之内选配,以便得到与焊材相适应的临界冷却速度,使之满足焊缝力学性能的要求。还要限制施焊环境的水蒸气分压(≤25mmHg),焊材的吸潮量要≤0.20%。另外,对NS110钢的低强匹配焊接接头也进行了大量的试验工作,结果表明:在焊缝强度比母材降低15%的条件下仍具有良好的综合性能,将其应用到潜艇壳体上是可以信赖的。     

45钢与40Cr钢焊接工艺研究

本文着重介绍了45钢与40Cr钢的焊接特点,焊接工艺的选择,试验条件及所采用的焊接工艺,并对试验结果进行了分析,表明45钢与40Cr钢选择合理的焊接工艺和方法,对焊后的接头性能相当于45钢退火状态下的机械性能,能够用于公司的批量焊接生产。     

TiAl＋Sb合金的热稳定性的研究

研究了退火处理对Ｔｉ－３４ｗｔ．％Ａｌ－０．５ｗｔ．％Ｓｂ合金的室温抗弯性能，显微组织，相组成和断口形貌的影响。发现，低于１０００℃退火处理，ＴｉＡｌ＋Ｓｂ合金的显微组织没有变化，其力学性能仍然保持较高的值。此合金成分适应高温使用条件。     

热处理对TiAl基铸造合金组织形态的影响

研究了不同热处理制度对Ti-47Al-2Nb-2Cr-0.2Si(原子分数，%）铸造合金组织形态的影响。研究表明Ti-47Al-2Nb-2Cr-0.2Si铸造合金快速冷却的铸造组织是单相γ的层片状组织；通过热处理可以有效控制合金的相组成，并且可以细化组织，经适当热处理，合金的晶粒尺寸可以达到40-50μm。     

Single Pass Laser-Arc Hybrid Welding of Maraging Steel Thick Sections

Maraging steel 250 grade plates of 10 mm thickness were welded in single pass using a laser-arc hybrid welding (LHW) setup comprising 3.5 kW CO₂ laser and synergic pulse metal inert gas (MIG) welding power source at a welding speed of 1 m/min. The influence of single-pass welding on the bead characteristics, microstructure, and mechanical properties was investigated. The size and volume fraction of reverted austenite was effectively reduced in the fusion zone. Moreover, the width of the heat-affected zones (HAZ) was reduced and the microhardness results did not show significant softening in the HAZ after post weld aging. Tensile testing of the welds in transverse direction showed 97.3% weld efficiency. The fusion zone exhibited K_Ic fracture toughness of 77.4 MPa√m which was affected by the distribution pattern of reverted austenite. The study vividly brings out the process advantages of LHW for accomplishing thick section welds of maraging steel in single pass with narrow groove and lesser filler wire consumption.     

铝锂合金搅拌摩擦焊研究

采用柱形带螺纹搅拌针搅拌摩擦焊接5 mm厚铝锂合金轧制板材,并对接头组织、力学性能及断裂特性进行了研究.接头形成差别明显的三个区域:焊核区、热机影响区和热影响区.拉伸实验表明,接头强度随着焊接速度的提高先增加,并于v=60mm/min处达到最大值340MPa;当v＞60mm/min时,接头强度迅速下降.铝锂合金搅拌摩擦接头断裂模式为韧脆混合型断裂,并以脆性断裂为主.     

铸造用TiAl母合金制备技术研究进展

目前,新型轻质高温结构材料TiAl合金铸造部件已经进入工业化生产阶段,急需工业级铸造用TiAl母合金的制造技术和评估体系作为支撑。结合了钢铁研究总院铸造TiAl合金工程化研究和应用成果,概述了国内外铸造TiAl合金材料和部件的工程化应用现状,在此基础上,提出了铸造TiAl母合金的化学成分、规格等技术要求,并进一步对比分析了2次自耗熔炼、自耗熔炼+凝壳熔炼、自耗熔炼+凝壳熔炼+自耗熔炼等母合金制备工艺的优缺点,最后提出了工业级铸造TiAl母合金的技术发展方向。