激光-MAG和MAG焊接Weldox960钢接头的组织与性能对比

分别采用激光-活性气体保护电弧焊(Laser-MAG焊)和MAG焊对Weldox960钢板进行焊接,对比分析了两种工艺焊接接头的显微组织及性能。结果表明:Laser-MAG焊接接头热影响区粗晶区的平均晶粒尺寸较小,为48μm,而MAG焊接接头的为95μm,两种焊接接头的显微组织基本相同,焊缝区组织为细小粒状贝氏体,细晶区组织为细小板条马氏体和粒状贝氏体,部分相变区组织为铁素体+粒状贝氏体;Laser-MAG焊接接头的热影响区宽度小于MAG焊接接头的,软化带也较窄,其拉伸性能和冲击性能均优于MAG焊接接头的,条件疲劳极限为320 MPa,高于MAG焊接接头的。     

EH36船板钢埋弧焊接头的组织和力学性能

采用埋弧焊工艺对EH36船板钢进行多道次、大热输入条件下的焊接试验,研究了焊接接头的显微组织和力学性能。结果表明:在大热输入条件下,焊缝组织由晶界铁素体、块状铁素体和少量针状铁素体组成,不存在侧板条铁素体,这对焊缝的力学性能有利;粗晶热影响区是受焊接热输入影响最严重的区域,冲击韧性最差的区域为焊缝;焊接接头的最高硬度出现在粗晶区靠近熔合线处,为222HV,最低硬度出现在细晶区,为181HV,未出现焊接软化区。     

Q345B低碳钢/20Mn23Al无磁钢异种钢焊接接头的组织及性能

采用E316LT0-1不锈钢焊丝对Q345B低碳钢和20Mn23Al无磁钢进行熔化极气体保护焊,研究了焊接接头的显微组织和力学性能.结果表明:接头填充焊层组织主要为骨骼状δ-铁素体和奥氏体,打底焊层组织主要为树枝状铁素体和奥氏体;Q345B钢侧过热粗晶区组织为贝氏体和魏氏体,相变重结晶区组织为珠光体和铁素体,20Mn23Al钢侧热影响区组织为孪晶奥氏体和少量铁素体;母材和焊缝中的合金元素发生互扩散,Q345B钢和20Mn23Al钢侧扩散层厚度分别约为15,25μm;接头拉伸性能优于Q345B钢但略差于20Mn23Al钢,接头焊缝区硬度最大,热影响区次之.     

5R60铝合金焊接接头微观组织与力学性能研究

针对中国兵器工业集团第五二研究所开发的高性能5R60铝合金在应用中对熔焊的需求,使用五二所研发的?1.6mm高性能5R59铝合金焊丝,采用MIG焊接方法焊接13mm厚5R60铝合金板材,并对焊接接头显微组织、断口形貌、拉伸力学性能和显微硬度等内容进行研究。研究结果表明：焊缝区和靠近焊缝一侧的热影响区晶粒为均匀细小的等轴晶,平均晶粒尺寸分别为9.6和18.4μm;焊缝组织中分布大量由Al、Sc、Zr、Ti元素组成的初生第二相,该相对提升促进焊缝组织晶粒细化、提升接头强度具有积极作用;显微硬度测试结果分析焊接接头热影响区宽度约为30mm;焊接接头最高抗拉强度和延伸率分别为367MPa和13%,平均抗拉强度和延伸率分别为358.3MPa和12.5%;焊缝区由于铸态组织缺陷成为性能最薄弱区域,平均显微硬度为90.5HV。     

不同焊接工艺下FB780钢焊接接头热影响区的显微组织和冲击韧性

用Gleeble-3500型热模拟试验机模拟单道次焊接条件下FB780钢焊接接头热影响区(HAZ)的热循环过程,研究了在不同焊接峰值温度及不同t8/5(由800℃冷却到500℃的时间)下HAZ的显微组织,并测试了不同焊接条件下HAZ的显微硬度和冲击韧性。结果表明:在t8/5相同的条件下,随着峰值温度的升高,HAZ组织粗化;当峰值温度一定时,随着t8/5的增加,铁素体板条变宽并逐渐融合,M/A组元粗化,粗大铁素体晶粒与细小准多边形铁素体晶粒混合,组织的均匀性恶化;在相同的峰值温度条件下,HAZ的硬度和冲击功均随着t8/5的增加而降低;在峰值温度为1 175℃,t8/5为6s条件下,HAZ的低温(-20℃)冲击断口形貌为韧窝花样,韧窝尺寸较大,HAZ的低温韧性与母材的相匹配,同时硬度较高,该工艺为最佳的单道次焊接工艺。     

核级手动截止阀Ω焊缝凝固缺陷成因研究

采用显微硬度测量、金相和扫描电镜(SEM)观察对不锈钢手动截止阀焊接接头各微区的硬度进行测量;对Ω焊缝、热影响区(HAZ)和母材的显微组织进行观察;对接头的断口形貌进行观测分析。结果表明:接头各区域的硬度分布差异不大,分布较为均匀,而2#试样HAZ的硬度高于1#。Ω焊缝金属柱状晶粗大,晶粒(柱状和胞状晶)的方向性强,晶间存在偏析,焊缝已形成沿晶界开裂。主要原因是:Ω焊缝装配间隙部位在冷却结晶时因液态填充不够,形成缩松、缩孔。在焊接应力/应变场作用下,拉伸应变或应变率超过此时材料的临界塑性和临界应变率时则产生焊接凝固裂纹。     

6061铝合金/Q235镀锌钢冷金属过渡熔钎焊接头的显微组织及拉伸性能

采用冷金属过渡(CMT)熔钎焊工艺对6061铝合金和Q235镀锌钢异种材料进行了对接焊,并对焊接接头的显微组织和拉伸性能进行了研究。结果表明:焊接接头表面成形质量良好;焊接接头由熔化区、热影响区和界面层等3部分构成;熔化区组织由α-Al固溶体和铝硅共晶组织组成,热影响区组织较母材的发生了粗化,界面层形成了金属间化合物(IMCs),界面层厚度约为8μm,且界面层向熔化区单向生长;6061铝合金母材侧的焊接热影响区的硬度最低(42HV),界面层的硬度最高(365HV);对接接头的抗拉强度为161 MPa,约为6061铝合金的0.69倍,抗拉强度明显高于搭接接头的。     

6mm厚304奥氏体不锈钢激光焊接工艺规律的研究

采用光纤激光器对6mm厚的304不锈钢进行焊接试验,通过对不同工艺参数下的焊接接头显微硬度、拉伸性能及显微组织进行测试与观察,研究激光功率、焊接速度对焊接接头中心等轴晶晶粒大小、柱状晶宽度的影响规律以及力学性能的影响规律.结果 表明:焊接接头硬度都比母材大,热影响区的硬度与母材接近;增大激光功率或减小焊接速度,焊缝柱状晶宽度以及中心等轴晶晶粒都逐渐增大,焊缝显微硬度逐渐减小,焊缝抗拉强度先增大后减小;当激光功率为2.9KW时,焊缝抗拉强度达到最大值711.5MPa,抗拉强度与母材强度接近,继续增加激光功率,焊缝组织粗化,焊接接头抗拉强度降低.     

X100管线钢焊接接头的显微组织和性能

利用光学显微镜、拉伸试验机、冲击试验机及维氏硬度计等对X100管线钢埋弧焊焊接接头的组织及性能进行了研究。结果表明:X100管线钢焊接接头粗晶区组织为粗大的先共析铁素体和粒状贝氏体,细晶区主要为细小的铁素体,不完全重结晶区为细晶铁素体、粗晶针状铁素体和粒状贝氏体混合组织;接头的抗拉强度平均值为576MPa,达到母材的80%,拉伸试样断裂于焊缝处;接头焊缝、热影响区的冲击功分别为198J和259J;焊缝区最高硬度为316HV,在临界温度热影响区(ICHAZ)和亚临界温度热影响区(SCHAZ)之间存在软化现象。     

薄板06Cr19Ni10不锈钢焊接接头组织与性能的研究

通过对微束等离子弧焊和冷金属过渡焊(CMT)的1.5 mm厚06Cr19Ni10奥氏体不锈钢薄板焊接接头的组织与性能的对比,发现微束等离子弧焊接头抗拉强度及疲劳强度均略低于冷金属过渡焊,两种焊接方法下接头弯曲性能均良好,焊缝区硬度均低于母材且CMT焊缝区硬度值略高于微束等离子弧焊,焊缝组织均为奥氏体+不同形态的δ铁素体组织,组织呈柱状晶。     

HAZ Characterization and Mechanical Properties of QP980-DP980 Laser Welded Joints

The QP980-DP980 dissimilar steel joints were fabricated by fiber laser welding. The weld zone(WZ) was fully martensitic structure, and heat-affected zone(HAZ) contained newly-formed martensite and partially tempered martensite(TM) in both steels. The super-critical HAZ of the QP980 side had higher microhardness(～ 549.5 Hv) than that of the WZ due to the finer martensite. A softened zone was present in HAZ of QP980 and DP980, the dropped microhardness of softened zone of the QP980 and DP980 was Δ 21.8 Hv and Δ 40.9 Hv, respectively. Dislocation walls and slip bands were likely formed at the grain boundaries with the increase of strain, leading to the formation of low angle grain boundaries(LAGBs). Dislocation accumulation more easily occurred in the LAGBs than that of the HAGBs, which led to significant dislocation interaction and formation of cracks. The electron back-scattered diffraction(EBSD) results showed the fraction of LAGBs in sub-critical HAZ of DP980 side was the highest under different deformation conditions during tensile testing, resulting in the failure of joints located at the sub-critical HAZ of DP980 side. The QP980-DP980 dissimilar steel joints presented higher elongation(～ 11.21%) and ultimate tensile strength(～ 1011.53 MPa) than that of DP980-DP980 similar steel joints, because during the tensile process of the QP980-DP980 dissimilar steel joint(～ 8.2% and 991.38 MPa), the strain concentration firstly occurred on the excellent QP980 BM. Moreover, Erichsen cupping tests showed that the dissimilar welded joints had the lowest Erichsen value(～ 5.92 mm) and the peak punch force(～ 28.4 k N) due to the presence of large amount of brittle martensite in WZ and inhomogeneous deformation.     

Effect of friction welding parameters on mechanical and metallurgical properties of ferritic stainless steel

Friction welding is one of the most economical and highly productive methods in joining similar and dissimilar metals. It is widely used in the automotive and aerospace industrial applications. Ferritic stainless steel (AISI430) is normally difficult to weld by fusion methods, due to the associated problems such as grain growth and retained austenite content. Such problems can be alleviated by the friction joining process. The present study utilized a continuous drive friction welding machine to join cylindrical specimens of ferritic stainless steel of similar composition and shape (equal diameter and length). The processing parameters such as friction pressure, friction time, upsetting pressure and upsetting time were changed in order to understand the role of parameters on the strength related aspects of friction processed joints. The joints were subjected to mechanical testing methods such as the uni-axial tension test, and charpy ‘v’ notch impact tests. The micro hardness variation across the joint zone was determined. Micro structural studies were also carried out. The characteristics such as tensile strength, toughness and microstructural aspects exhibited by friction processed joints were compared to parent materials.     

Study on microstructure and mechanical properties of dissimilar steel joint developed using friction stir welding

In the present study, microstructure and mechanical properties of dissimilar weld of structural steel and ferritic stainless steel (FSS) plates of thickness 3 mm were investigated. The plates were butt welded by friction stir welding and defect-free welds were produced at a traverse speed of 20 mm/min and rotational speed of 508 rpm using a tungsten carbide tool. The weld joint consisted of alternate bands of both steels resembling an onion ring pattern. In the weld joint, six distinct regions were found including both the base metals. The stir zone of structural steel revealed refined grain structure of ferrite, pearlite, and martensite whereas in ferritic stainless side, highly refined ferritic grains with grain boundary martensite was observed and also confirmed by x-ray diffraction (XRD). The hardness of the weld joint varies from 186 to 572 HV. This scatter of hardness in stir zone is due to the presence of metal from both sides. The ultimate tensile and yield strengths of the transverse weld specimens was higher than the structural steel base metal whereas lower than the ferritic stainless steel, having fracture from structural steel side.     

CMT自动焊在不锈钢城轨车辆中的应用

文章介绍了CMT自动焊接的工艺及设备,说明其可以应用于不锈钢城轨车辆顶盖焊接结构及接头形式。本文对CMT自动焊接在顶盖焊接过程中出现的问题进行了分析研究,通过规范工艺参数及工艺要求,解决了应用过程出现的问题,并在项目中推广实施。     

SS400钢焊接接头抗断性能的数值评估

SS400钢是一种超细晶粒、超纯净、具有优良综合力学性能的新一代钢铁材料，其焊接结构性能的研究对其推广应用具有重要的意义。文中通过数值分析方法，以SS400母材性能为参照，对其实际焊接接头的抗断裂性能进行评估。采用MARC商用软件，对不同中心贯穿裂纹尺寸的SS400母材及其实际焊接接头拉伸板模型进行三维有限元计算和拉伸过程模拟。焊接方法为脉冲熔化极混合气体保护焊，焊接板的中心裂纹处于焊缝与热影响区之间的熔合区。用作比较的母材板的裂纹尺寸和位置、网格划分、边界条件等与焊接板完全相同。根据计算结果，分析焊接接头力学不均匀性对应力应变场的影响，并依据全面屈服理论对断裂参量CTOD进行分析比较。结果表明，焊接接头的CTOD值均低于同裂纹尺寸的纯母材。因此，该焊接接头拉伸板的抗断性能应优于纯母材。     

Microstructure and mechanical properties of similar and dissimilar stainless steel electron beam and friction welds

Microstructure and mechanical properties of similar and dissimilar welds of austenitic stainless steel (AISI 304), ferritic stainless steel (AISI 430), and duplex stainless steel (AISI 2205) have been studied. Welding processes electron beam welding and friction welding were used. Optical, scanning electron microscopy, and electron probe microscopy were carried out to study the microstructural changes. Residual stress, hardness, tensile strength, and impact toughness testing were conducted to study mechanical behavior. Dissimilar metal electron beam welds of austenitic–ferritic, ferritic–duplex, and austenitic–duplex stainless steel welds contained coarse grains, which are predominantly equiaxed on austenitic, duplex stainless steel side, and they are columnar on the ferritic stainless steel side. Diffusion of elements was significant in electron beam welding and insignificant in friction welds. Austenitic–ferritic stainless steel exhibited tensile residual stress on the ferritic stainless steel side adjacent to the interface, compressive stresses on the austenitic stainless steel side that matches with the delta ferrite microstructure observed in this region. High compressive stresses were noted on duplex stainless steel side interface compared to austenitic stainless side interface. The highest tensile strength was observed in duplex–austenitic stainless steel joints. The impact strength and notch tensile strength of electron beam weldments are higher than the friction weldments. All electron beam and friction welds showed toughness lower than parent metals.     

机械振动对激光焊接接头组织的影响

振动焊接工艺能有效细化接头组织晶粒,降低残余应力,提高焊接质量。为了研究振动焊接工艺在激光焊接方面的应用,选用316不锈钢作为试验材料,利用机械振动辅助激光焊接的工艺方法,通过改变机械振动参数和焊接速度,利用光学显微镜和扫描电镜观察焊后接头组织,对比分析不同振动频率和焊接速度下接头的微观组织形貌。结果表明,机械振动可以细化焊后组织中形成的柱状晶,使柱状枝晶破碎且向不同方向生长,晶轴间与焊缝中心处的等轴晶增加。提高焊接速度后,振动的加入能够细化焊缝区出现的粗大柱状晶。同时,振动可以减少焊后在奥氏体基体晶界处形成的网状高温铁素体和点状碳化物,使其趋于弥散。试验还对焊接接头进行显微硬度测试,发现振动焊接下得到的焊缝区接头组织硬度较高,且较高共振频率下硬度增加明显。     

Investigation of mechanical properties of friction-welded AISI 304 with AISI 1021 dissimilar steels

Austenitic stainless steel and low alloy steels are extensively used in various automotive, aerospace, nuclear, chemical, and other general purpose applications. Joining of dissimilar metals is one of the challenging tasks and most essential need of the present-day industry. It has been observed that a wide range of dissimilar materials can be easily integrated by friction welding. The objectives of the present investigation were obtaining weldments between austenitic stainless steel (AISI 304) with low alloy steel (AISI 1021) and optimizing the friction welding parameters in order to establish the weld quality. In the present study, an experimental setup was designed in order to achieve friction welding of plastically deformed austenitic stainless steel and low alloy steel. AISI 304 and AISI 1021 steels were welded by friction welding using five different axial pressures at 1,430 rpm. The joining performances of friction-welded dissimilar joints were studied, and influences of these process parameters on the mechanical properties of the friction-welded joints were estimated. The joint strength was determined with tensile testing, and the fracture behavior was examined by scanning electron microscopy (SEM) and was supported and backed by energy dispersive spectroscopy (EDS) analysis. Furthermore, the proposed joints were tested for impact strength, and the microhardness across the joint was also evaluated.     

不锈钢复合板焊接接头晶间腐蚀失效分析

针对不锈钢复合板焊接接头出现晶间腐蚀裂纹问题,采用光学显微镜、扫描电镜、XRD等技术手段对复合板焊接接头的组织、成分以及相组成进行检测和分析,对焊接工艺规范和热处理制度对焊接接头耐蚀性的影响进行探讨。结果表明,接头焊缝区铁素体含量18．3％,晶粒度9．5级,过渡层焊缝铬的含量9．58％,低于耐蚀性要求;接头产生了σ等硬脆相,这些因素都增大晶间腐蚀敏感性;焊接线能量过大,将降低接头的腐蚀性能;复合板整体消应热处理可以取消。     

Microstructure and mechanical properties of electron beam-welded AISI 409M-grade ferritic stainless steel

This paper deals with the microstructure and mechanical characterization of electron beam-welded AISI 409M-grade ferritic stainless steel joints. Single-pass autogenous welds free of volumetric defects were produced at a welding speed of 1,000?mm/min. The joints were subjected to optical microscopy, scanning electron fractography, microhardness, transverse and longitudinal tensile, bend and charpy impact toughness testing. The coarse ferrite grains in the base metal were changed into fine equiaxed axial grains and columnar grains as a result of characteristic rapid solidification of electron beam welds. Tensile testing indicates overmatching of the weld metal relative to the base metal. The joints exhibited acceptable impact toughness and bend strength properties.