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.     

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.     

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.     

Microstructural studies and impact toughness of dissimilar weldments between AISI 316 L and AH36 steels by FCAW

In this study, AISI 316 L austenitic stainless steel and AH36 low-alloy ship building steel pair were joined with flux-cored arc welding method by using E309LT1-1/4 filler metal under four different shielding gas compositions containing CO₂ at different ratios. Microstructure, impact toughness of welded materials, and their microhardness distribution throughout joining were determined. In macro- and microstructure examinations, stereo optical microscope, scanning electron microscope (SEM), SEM/energy dispersive spectroscopy, and SEM/mapping analysis techniques were used. After notched impact toughness, fracture surfaces were examined using the scanning electron microscope. This study investigated effects of shielding gas composition on microstructure, impact toughness, and microhardness distribution of transition zone between AH36 steel and weld metal of joined material. It is observed that based on an increase in amount of CO₂ in shielding gas, impact toughness values of the weldment decreased. Microhardness values change throughout weld metal depended on shielding gas composition. Moreover, an increase in amount of CO₂ within shielding gas decreased δ-ferrite amount in weld metal. The increase in amount of CO₂ within shielding gas leads to expanded transition zone in interface between AH36 and weld metal and also affects notched impact toughness values negatively due to the inclusion amounts occurring in weld metal and hence caused it to decrease.     

The effects of casting and forging processes on joint properties in friction-welded AISI 1050 and AISI 304 steels

The aim of the present study was to investigate the effects of investment casting and forging process on the microstructure and mechanical properties of friction weldments, AISI 1050–AISI 304. A continuous-drive friction welding device with the automatic control ability of friction time and forging pressure was designed and constructed. Factorial design of experiments was performed to join investment cast AISI 1050 steels and forged AISI 1050 steels with AISI 304 austenitic stainless steel with respect to the optimized process parameters. The joint performance was evaluated by tensile and hardness tests performed parallel and perpendicular to the weld interface. Microstructure of forged parts under friction welding was examined using optical microscopy, scanning electron microscopy, and energy-dispersive spectroscopy. Results of microstructural studies were compared with those of friction welding of investment cast parts. The results reveal that a recrystallized region or a mechanically mixed layer was formed on the AISI 304 side near the weld interface, depending on friction time and friction pressure. Friction welding of forged parts always exhibited higher tensile strength, lower hardness, and more upset than the cast parts.     

Effects of welding wire and torch weaving on GMAW of S355MC and AISI 304L dissimilar welds

Dissimilar welding of austenitic stainless steel (ASS) to low-alloy structural steel is widely used in the power generation industry. The formation of brittle martensite and hot cracking susceptibility in the single-phase austenite microstructure are the main concerns related to the metallurgy of this kind of weld. This study investigates the effect of different welding wires and the weaving technique on the quality, microstructure and microhardness of fillet weld joints between AISI 304L austenitic stainless steel and S355MC low-alloy structural steel. Using robotised synergic gas metal arc welding (GMAW), three different filler wires were used to weld specimens with and without weaving. The macro-sections of the fillet welds were inspected and the dilution rates and ferrite numbers (FN) measured. The microstructure was also inspected and microhardness values recorded. Porosity was discerned in two weld samples made with the use of weave beads. The measured FNs for all the weldments were very close to estimations from the Schaeffler diagram. The formation of a narrow martensitic band on the ferritic side of the weld metal was detected for most of the specimens. It is concluded that weaving decreased the dilution rate and increased the FN. However, no obvious effect on the microstructure and hardness as a result of using the weaving technique was noticed.     

基于钴基合金覆层的多层金属热锻模原型制备与性能

基于功能梯度材料(FGM)的思想制备多层金属热锻模是提高模具寿命的有效方法。采用焊条电弧堆焊制备了多层金属热锻模的原型试样,试样经焊后热处理后,进行了金相组织分析、显微硬度测试、磨损实验和冲击韧性测试等实验。实验结果表明:钴基合金堆焊层与W6Mo5Cr4V2堆焊层界面冶金结合情况良好;截面显微硬度呈梯度分布,表面钴基合金硬度达到492HV;制备的多层金属试样耐磨性是H13钢耐磨性的2.5倍,冲击韧性处于合理范围。     

Investigation on microstructure and mechanical properties of ni-based alloy overlayer by ultrasonic impact treatment

Journal of Mechanical Science and Technology - Ultrasonic impact treatment (UIT) was performed on the Ni-based alloy overlayer of austenitic stainless steel pipe girth weld. The difference of...     

铝基复合材料─不锈钢摩擦焊焊接接头显微组织的电镜研究

利用电子显微镜技术系统地观察了铝基复合材料（ＭＭＣ）与奥氏体不锈钢之间摩擦焊焊接接头中的显微组织变化规律。发现强度较高的奥氏体不锈钢在焊接过程中发生了明显的塑性变形，焊接界面附近不同部位变形机制和特征不同，变形方式主要是形成形变孪晶、滑移带和位错亚结构。首次在透射电镜（ＴＥＭ）下观察到了一个由微晶氧化物组成的过渡层组织。     

Effect of welding parameters on mechanical properties and optimization of pulsed TIG welding of Al-Mg-Si alloy

An attempt has been made to study the effect of pulsed TIG welding process parameters on dilution and mechanical properties such as notch tensile strength, hardness, and impact toughness in as-welded condition. Pulsed TIG welds exhibited lower notch tensile strength and impact toughness than the parent metal due to interdendritic network microstructure features. Taguchi method was used to optimize the pulsed TIG welding process parameters of heat-treatable (Al-Mg-Si) aluminum alloy weldments for maximizing the mechanical properties. An inverse relationship has been observed between the notch tensile strength and impact toughness.     

Mechanical and metallurgical properties of friction welded AISI 304 austenitic stainless steel

Owing to the superior properties, of stainless steel it is pertinent to make use of it in various automotive, aerospace, nuclear, chemical and cryogenic applications. It is observed that a wide range of dissimilar materials can be easily integrated by solid phase bonding techniques, such as friction welding and explosive bonding. This study mainly focuses on friction welding of AISI 304 austenitic stainless steel. The friction processed joints are evaluated for their integrity and quality aspects. Friction welding of austenitic stainless steel was carried out using a KUKA friction welding machine (Germany). As the friction time increased, the fully plastically deformed zone (region I) in the vicinity of the bond line becomes increased. In contrast, an increase in friction time will decrease the region (region II) where the grains are partly deformed and grown. Tensile test results indicated that, the joint strength is decreased with an increase of the friction time. The detailed fractographic observation confirmed that the rupture occurred mostly at the joint zone and partly through the base material.     

Mechanical and metallurgical properties of friction welded AISI 304 austenitic stainless steel

Owing to the superior properties, of stainless steel it is pertinent to make use of it in various automotive, aerospace, nuclear, chemical and cryogenic applications. It is observed that a wide range of dissimilar materials can be easily integrated by solid phase bonding techniques, such as friction welding and explosive bonding. This study mainly focuses on friction welding of AISI 304 austenitic stainless steel. The friction processed joints are evaluated for their integrity and quality aspects. Friction welding of austenitic stainless steel was carried out using a KUKA friction welding machine (Germany). As the friction time increased, the fully plastically deformed zone (region I) in the vicinity of the bond line becomes increased. In contrast, an increase in friction time will decrease the region (region II) where the grains are partly deformed and grown. Tensile test results indicated that, the joint strength is decreased with an increase of the friction time. The detailed fractographic observation confirmed that the rupture occurred mostly at the joint zone and partly through the base material.     

Cryogenic fracture toughness evaluation for austenitic stainless steels by means of unloading compliance method

Most research to date concerning the cryogenic toughness of austenitic stainless steels has concentrated on the base metal and weld metal in weldments. The most severe problem faced on the conventional austenitic stainless steel is the thermal aging degradation such as sensitization and carbide induced embrittlement. In this paper, we investigate the cryogenic toughness degradation which can be occurred for austenitic stainless in welding. The test materials are austenitic stainless JN1, JJ1 and JK2 steels, which are materials recently developed for use in nuclear fusion apparatus at cryogenic temperature. The small punch (SP) test was conducted to detect similar isothermally aging condition with material degradation occurred in service welding. The single-specimen unloading compliance method was used to determine toughness degradation caused by thermal aging for austenitic stainless steels. In addition, we have investigated size effect on fracture toughness by using 20% side-grooved 0.5TCT specimens.     

Effect of process parameters on friction stir welding of aluminum alloy 2219-T87

In this work, successful friction stir welding of aluminum alloy 2219 using an adapted milling machine is reported. The downward or forging force was found to be dependent upon shoulder diameter and rotational speed whereas longitudinal or welding force on welding speed and pin diameter. Tensile strength of welds was significantly affected by welding speed and shoulder diameter whereas welding speed strongly affected percentage elongation. Metallographic studies revealed fine equiaxed grains in weld nugget and microstructural changes in thermo-mechanically affected zone were found to be the result of combined and interactive influences of frictional heat and deformation. A maximum joining efficiency of 75% was obtained for welds with reasonably good percentage elongation. TEM studies indicated coarsening and/or dissolving of precipitates in nugget. For the gas metal arc weld, SEM investigations revealed segregation of copper at grain boundaries in partially melted zone.     

钢-铝异种合金脉冲激光焊焊缝表征分析

采用Nd:YAG激光焊对304不锈钢和5052铝合金进行异种金属焊接,分别以峰值功率、焊接速度、离焦量和脉冲频率等工艺参数设计24组工艺试验,并对比分析未熔合、熔合和焊穿3种焊缝表面表征。运用激光点位移传感器测量焊缝高度,探索焊缝高度随激光功率等工艺参数的变化趋势,得出钢-铝焊缝3种表面形貌的工艺参数区间。分析结果表明,焊缝的表面形貌是由激光单点能量、离焦量和脉冲频率等因素共同决定,焊缝高度与峰值功率、焊接速度、离焦量和脉冲频率等工艺参数有一定的变化规律。     

线能量对SAF2507钢焊接接头性能的影响

双相不锈钢的焊接与一般奥氏体不锈钢的焊接有许多不同之处,焊接热循环对接头的组织变化有很大影响,而焊接线能量对焊接热循环有直接的影响。通过采用不同的焊接规范参数,焊接4组试件,并通过微观金相、耐腐蚀倾向试验等方法,分析比较试验结果,评价焊接线能量对00Cr25Ni7Mo4N(2507)焊接接头组织变化、耐腐蚀(点蚀)性能和冲击韧性的影响,为该种钢选择合适的焊接规范参数,提供了依据。     

Investigation on the resistance spot-welded austenitic/ferritic stainless steel

In this work, the effect of weld current on joining capability of austenitic stainless steel (AISI 304) and ferritic stainless steel (AISI 430) sheets with application of resistance spot welding process was investigated. Macrostructure, microstructure, microhardness, tensile shear strength, and failure mode of welded materials were evaluated for different weld currents. The values of weld current were 2.5, 3.75, and 5 kA. It was found that when the weld current increased, the nugget size and the weld strength were increased. Two distinct failure modes including interfacial and pullout were observed during tensile shear test. Finally, an adequate weld current was obtained.     

硼对低合金高强钢大热输入焊缝韧性的影响

对不同硼(B)的质量分数的低合金高强钢大热输入焊缝进行组织性能研究,分析、讨论B对低合金高强度(High strength low alloy, HSLA)钢焊缝韧性的影响规律。研究表明,低合金高强钢焊缝中适量增加B元素质量分数可提高组织中针状铁素体质量分数,有效细化焊缝组织,而当B元素过量时则使焊缝组织中的针状铁素体质量分数下降,组织粗化。同时,适量B元素还可抑制晶界先共析铁素体的产生;随着焊缝中B质量分数的增大,贝氏体转变得到促进,M-A组元总量提高,从不含B时的2.4%提高到B质量分数为0.008 8%时的5.7%,且其尺寸也相应增大,由平均尺寸2.14 μm增加至2.83 μm。由于B质量分数增加先促进针状铁素体后促进贝氏体形成,因此其对焊缝韧性的影响呈现抛物线变化规律,即低温冲击吸收能量随着B质量分数的增加先上升后下降。在焊缝Ti质量分数约为0.03%的条件下,B质量分数为0.005 2%时,焊缝获得了最佳的低温冲击韧度。     

氧化铈对低合金钢焊条熔敷金属的影响

基于现有焊条性能的特点,针对典型低合金钢焊条(E5515型焊条)当焊接碳当量CE>0.4%的中、高碳钢时,焊接性较差的问题,在新型低合金钢焊条药皮配方开发研制中采取药皮过渡微量的稀土氧化物.通过冲击韧度、拉伸、硬度和金相等试验研究氧化铈对低合金钢焊条熔敷金属力学性能影响和组织的影响,利用扫描电子显微镜对显微组织进行观察分析,用X射线能谱仪进行能谱分析.分析研究结果表明,加入适量的稀土氧化物能够细化熔敷金属显微组织,提高熔敷金属的冲击韧度:稀土能降低熔敷金属中的氢,从而显著降低钢的脆性转变温度.当氧化铈加入量最佳时,熔敷金属的抗拉强度提高了43.27%,屈服强度提高了52.11%,冲击韧度提高了26.49%,而硬度却不下降.     

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.