6005A铝合金CMT与MIG焊接头组织及性能研究

针对2mm厚6005A铝合金采用冷金属过渡(CMT)和熔化极惰性气体保护(MIG)焊接技术进行焊接,研究了两种焊接接头的力学性能、拉伸断口形貌,接头不同位置的微观组织。研究表明,CMT焊接头的抗拉强度好于MIG焊接头,达到母材的70%,焊缝组织更为细小;两种焊接接头断裂位置均为热影响区,CMT焊接接头为韧性断裂,MIG焊接接头为韧性断裂与准解理断裂的混合断裂。     

Characteristics of Welding Crack Defects and Failure Mode in Resistance Spot Welding of DP780 Steel

The mechanical properties of welded joints in resistance spot welding of DP780 steel were tested,and three dif-ferent types of welding cracks in welded joints were investigated by optical microscopy,scanning electron microscopy and electron back-scattered diffraction.Finally,the failure mode of the welded joints in shear tensile test was dis-cussed.It is found the shear tensile strength of welded joints can be greatly improved by adding preheating current or tempering current.The surface crack in welded joint is intergranular fracture,while the inner crack in welded joint is transgranular fracture,and the surface crack on the edge of the electrode imprint can be improved by adding prehea-ting current or tempering current.The traditional failure mode criterion advised by American Welding Society is no longer suitable for DP780 spot welds and the critical nugget size suggested by Pouranvari is overestimated.     

Performance evaluation of OOCr11NbTi perforated-plasma-arc-welded joint

Based on a 00CrllNbTi ferritic stainless steel plate produced by Baosteel,the plasma arc welding was performed without filler wire.The mechanical properties of the welded joints were tested,as a result,the transverse tensile strength of the welded joints decreased to a certain extent in comparison with that of the base metal,but the bending performance and plasticity of the welded joint were good.     

Corrosion Behavior of Welded Joints of Al-6Mg Alloy with Trace Scandium Addition

Al-6Mg alloy with trace Sc addition was prepared by means of melting-casting.The samples of the welded joints of Al-6Mg alloy with trace Sc addition were made by method of manual argon-arc welding.Neutral salt spray test was carried out by referring to GB/T10125-1997 and GB6384-1986 practice.Exfoliation testing was carried out in accordance with the method of Al-Mg alloy exfoliation corrosion test.The corrosion behaviors of the welded joints of AlMg alloy with high level of Mg and trace Sc addition were studied.The microstructures of the welded joints were observed by using optical microscope and transmission electron microscope.The corrosion resistance mechanism of the alloy was also involved.This work intended to determine if the welded joints of Al-6Mgalloy with trace Sc addition can have excellent corrosion resistance, when their strength are clearly improved.The results show that trace content of Sc refines the grains of alloys effectively, raises remarkably the corrosion resistance of the welded joints of Al-6Mg alloy with trace Sc addition.The corrosion resistance mechanisms are that there is free of continuous grain boundary precipitation or network which could be susceptible to corrosion in the microstructure of welded joints.     

Effect of the Heat-Treatment Conditions on the Structure and Mechanical Properties of the Base and Weld Materials of the VT41 Alloy Blisks in the HPC of an Advanced Engine

The influence of the conditions of complete and incomplete postwelding annealing on the strength properties of the welded joints of a VT41 alloy is studied. These annealing conditions are developed for the ring welded joints of a VT41 alloy. The optimum conditions are determined for the production of large welded joints of a VT41 alloy for a high-pressure compressor in an advanced engine. The mechanical properties of the base and weld metals are compared after complete and incomplete postwelding annealing. The microstructure of the welded joints after heat treatment is investigated.     

氟化稀土对异种钢焊接接头抗裂性能的影响

本文研究了用高合金焊条焊接带耐蚀喷焊层低碳钢时稀土对异种钢焊接接头抗裂性能的影响,结果表明：在焊条药皮中加入适量稀土可以提高接头的抗裂性能,但是加入量过多又会产生不良影响。适量稀土的加入能够改善焊缝组织,使异种钢焊接接头热影响区变窄、过热区晶粒长大受到抑制、过渡区脆硬层硬度显著降低,有利于异种钢焊接接头抗裂性能的提高。     

宝钢T92钢管焊接性能试验及焊接接头运行评价

检验及分析评价了宝钢产SA-213 T92钢高压锅炉管的焊接工艺性能及焊接接头性能,对T92钢焊接接头挂管电厂锅炉实炉运行考验,并对服役1年的T92钢焊接接头进行了高温持久强度试验及评价。结果表明,宝钢T92高压锅炉管焊接工艺性能及接头性能各项技术指标均符合DL/T 868—2004标准要求,实炉运行业绩良好,服役1年的T92管焊接接头高温持久强度总体仍达到或超过GB 5310—2008、EN10216—2007标准要求。     

马弗炉用高温合金钢电弧焊接的接头性能

采用钨极氩弧焊与手工电弧焊相结合的方法完成马弗炉高温合金钢的焊接,并通过对其焊接接头常温与高温力学性能的测试,结合焊接接头金相组织的观察,对BSTMUF601与16MnR、SUS310S等异种钢焊接的高温焊接热影响区性能变化给予解析。结果显示,一定焊接工艺条件下的BSTMUF601具有等同于进口材料的焊接接头性能,可用于马弗炉设备制造以及在役马弗炉的修复。     

Effect of Scandium on Corrosion Resistance of Welded Joint of Al-6Mg-Zr Alloy

Al Mgalloyshavebeenwidelyusedinmanyin dustries,especiallyinmarineandaircraftapplica tions,duetotheirgoodweldability,ductilityandex cellentcorrosionresistance.Beingthenon heattreat ablealloys,thesematerialsderivetheirstrengthpri marilyfromsolidsolutio…     

Effect of Welding Processes on Tensile and Impact Properties, Hardness and Microstructure of AISI 409M Ferritic Stainless Joints Fabricated by Duplex Stainless Steel Filler Metal

The effect of welding processes such as shielded metal arc welding, gas metal arc welding and gas tungsten arc welding on tensile and impact properties of the ferritic stainless steel conforming to AISI 409M grade is studied. Rolled plates of 4 mm thickness were used as the base material for preparing single pass butt welded joints. Tensile and impact properties, microhardness, microstructure and fracture surface morphology of the welded joints have been evaluated and the results are compared. From this investigatio.n, it is found that gas tungsten arc welded joints of ferritic stainless steel have superior tensile and impact properties compared with shielded metal are and gas metal arc welded joints and this is mainly due to the presence of finer grains in fusion zone and heat affected zone.     

高性能WNQ690钢气体保护焊试验研究

以WNQ690钢为研究对象,采用气保护焊接工艺,焊接线能量控制在15kJ／cm,WER70NH匹配WNQ690钢进行焊接,研究WNQ690钢焊接性能及焊接组织结构。接头抗拉强度为750MPa,冷弯性能优良,焊缝-40℃平均冲击功为137J,熔合线及热影响区冲击功均达到较高水平,焊接接头的HV10硬度在234-300之间,说明WNQ690钢淬硬倾向较小。WNQ690钢材的组织为回火贝氏体,焊接接头过热区组织为贝氏体,焊缝中含有较多的针状铁素体和少量的先共析铁素体,焊接热影响区的细小贝氏体组织使焊接热影响区具有较高的冲击韧性。     

Effect of welding processes on tensile, impact, hardness and microstructure of AISI 409M ferritic stainless joints fabricated using duplex stainless steel filler metal

 The present investigation is aimed at to study the effect of welding processes such as shielded metal arc welding, gas metal arc welding and gas tungsten arc welding on tensile and impact properties of the ferritic stainless steel conforming to AISI 409M grade. Rolled plates of 4 mm thickness were used as the base material for preparing single pass butt welded joints. Tensile and impact properties, micro hardness, microstructure and fracture surface morphology of the welded joints have been evaluated and the results are compared. From this investigation, it is found that gas tungsten arc welded joints of ferritic stainless steel showed superior tensile and impact properties compared with shielded metal arc and gas metal arc welded joints and this is mainly due to the presence of finer grains in fusion zone and heat affected zone.     

镁合金焊接接头耐腐蚀性能研究现状

对近年来镁合金及其焊接接头腐蚀性能的研究现状和最新成果与进展进行了总结,指出了目前在镁合金焊接接头腐蚀研究领域存在的问题与不足,最后分析了镁合金焊接接头腐蚀的研究方向和工作重点。     

Numerical Studies of Estimation of Fracture Parameters for Mismatched Welded Joints with HAZ Cracks

An idealized tri-material assumption is established to describe the constitutive relationship of mismatched welded joints by considering the influence of heat affected zone(HAZ).The fracture parameters Jand C*are estimated for mismatched welded joints with HAZ cracks by finite element analysis with ABAQUS.A middle crack tension(M(T))specimen is utilized in the analysis for different material properties and geometries of the weldment.The influence of mechanical property and geometry on the fracture parameters Jand C*of the specimen is discussed for the welded joints with HAZ crack.The results suggest that the HAZ property is a significant factor in the estimation of Jand C*for the mismatched welded joint with HAZ crack.     

Properties of the welded joints of manganese steel made by low-frequency pulsed arc welding

The structure, the mechanical properties, the impact toughness, and the fracture mechanisms of the welded joints made of steel 09G2S plates by direct current welding and pulsed arc welding with a modulated arc current in the frequency range 0.25–5.0 Hz are studied. The application of low-frequency pulsed arc welding allowed us to form welded joints with a fine-grained structure in the weld metal and the heat-affected zone and to achieve a higher impact toughness and a longer cyclic fatigue life as compared to the welded joints fabricated by direct current welding. The achieved effect manifests itself over the entire testing range from 20 to–60°C.     

Fatigue Assessment of Cruciform Joints Welded with Different Methods

The advantages of the relatively new laser welding method are low welding distortions and high productivity, and it opens new opportunities for welding of steel structures in the automotive and heavy machinery industries. There is a need for understanding the fatigue strength and to develop fatigue design curves for laser welded joints. In this paper fatigue testing and weld quality of Hybrid Nd: YAG laser/MAG and MAG welded non‐load carrying cruciform joints is examined. Four batches were produced, tested and the results were compared. The local weld geometry of the cruciform welded joints was measured and analysed. The measured parameters were used to calculate the stress concentration factors by implementing FE‐models, in order to anticipate the influence of size of weld geometrical parameters on the stress concentrations. Residual stress measurement was carried out close to the toe region using the X‐ray diffraction method and weld defects (cold laps) in the cracked specimens was measured.     

超细晶粒钢筋焊接接头的疲劳强度

 超细晶粒钢是一种细晶强化的新一代钢铁材料，焊接加工对焊接接头疲劳性能的影响是人们关注的问题。参照建设部《钢筋焊接接头试验方法标准》的规定，对超细晶粒钢建筑钢筋闪光对焊、电渣对焊接头的疲劳寿命进行了测试。测试结果表明：高载荷下，闪光对焊接头的疲劳寿命明显优于电渣对焊接头，随着载荷的降低，2种接头的差距变小。在200万次循环下，两者的疲劳强度基本相当。     

使用状态对Q690CFD焊接接头性能的影响

针对煤矿机械、港口机械等对低成本焊接结构用高强钢的需求,宝钢开发了低成本TMCP高强钢Q690CFD,具有优异的综合力学性能和抗冷裂纹性能.对于高强钢厚板而言,焊后热处理工艺非常关键,它对接头的力学和使用性能有重要影响.在制造过程中,根据用户不同的服役条件,焊接结构要求不同的使用状态,比如焊态、消氢处理态和消应力处理态.按照相关的国家标准,采用实芯焊丝BH700-Ⅱ,制作了Q690CFD的富氩气保焊接头,分析接头的不同使用状态,包括焊态、300℃消氢处理和580℃消应力处理对Q690CFD/BH700-Ⅱ接头性能的影响.结果表明,焊态、消氢处理态和消应力处理态下,接头的力学性能均满足相关国家标准;按接头性能优劣来分,从好到差的顺序为：消氢处理态、焊态、消应力处理态.消氢处理可以一定程度上增加接头的冲击性能,但消应力处理使接头的冲击性能变差.     

Microstructural Evolution and the Effect on Hardness and Impact Toughness of Sanicro 25 Welded Joints After Aging at 973 K

Metallurgical and Materials Transactions A - Sanicro 25 tubes were welded using Alloy 617 mod. as the filler material, and the welded joints were aged at 973 K up to 10,000 hours....     

High cycle fatigue behavior of DP980 steel and DP980 steel laser welded joints

For the study of the DP980 steel high cycle fatigue property, high fatigue tests of DP980 steel and DP980 steel laser welded joints were carried out with fatigue testing machine, the Basquin equation was concluded. Microstructures and fractures were analyzed by optical microscope and scanning electron microscope. The results show that DP980 steel laser welding joints have the weld concavity at the welding root and top, the quality of welded joints is medium. The fatigue limit of DP980 steel is 341MPa, the fatigue limit of DP980 steel laser welded joint is 148MPa, the fatigue limit decreases by 50% compared with the fatigue limit of the base metal. For DP980 steel, the crystal boundary of the ferrite/martensite is the main location of micro cracks initiation, the fatigue fracture of DP980 steel is the quasi cleavage fracture. For DP980 steel laser welding joints, the fatigue cracks initiation is located in the weld concavity, not in the heat affected zone, the fatigue fracture is cleavage fracture. DP980 steel and DP980 steel laser welding joints crack propagation is characterized by the obviously fatigue striations coupled with secondary cracks.