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.     

Effect of Autogenous Arc Welding Processes on Tensile and Impact Properties of Ferritic Stainless Steel Joints

 The effect of autogeneous arc welding processes on tensile and impact properties of ferritic stainless steel conformed to AISI 409M grade is studied. Rolled plates of 4 mm thickness have been used as the base material for preparing single pass butt welded joints. Tensile and impact properties, microhardness, microstructure, and fracture surface morphology of continuous current gas tungsten arc welding (CCGTAW), pulsed current gas tungsten arc welding (PCGTAW), and plasma arc welding (PAW) joints are evaluated and the results are compared. It is found that the PAW joints of ferritic stainless steel show superior tensile and impact properties when compared with CCGTAW and PCGTAW joints, and this is mainly due to lower heat input, finer fusion zone grain diameter, and higher fusion zone hardness.     

Comparison of Friction Stir and Gas Tungsten Arc Weldments of Modified 12 wt.% Cr Ferritic Stainless Steel

This paper presents the comparative evaluation of microstructural features and mechanical properties of a friction stir welded (solid‐state) and gas tungsten arc welded (fusion weld) 409 M grade ferritic stainless steel joints. Optical microscopy, microhardness, transverse tensile and impact tests were performed. The coarser ferrite grains in the base material are changed to very fine grains consisting of a duplex structure of ferrite and martensite due to the rapid cooling rate and high strain induced by severe plastic deformation caused by frictional stirring. On the other hand, grain growth was observed in the fusion zone as well as heat affected zone of the gas tungsten arc welded joint resulting in deterioration of mechanical properties.     

Effect of Welding Processes and Consumables on Tensile and Impact Properties of High Strength Quenched and Tempered Steel Joints

Quenched and tempered steels are prone to hydrogen induced cracking in the heat affected zone after welding. The use of austenitic stainless steel consumables to weld the above steel was the only available remedy because of higher solubility for hydrogen in austenitic phase. In this investigation, an attempt was made to determine a suitable consumable to replace expensive austenitic consumables. Two different consumables, namely, austenitie stain less steel and low hydrogen ferritic steel, were used to fabricate the joints by shielded metal are welding （SMAW） and flux cored arc welding （FCAW） processes. The joints fabricated by using low hydrogen ferritic steel consumables showed superior transverse tensile properties, whereas joints fabricated by using austenitic stainless steel consumables exhibited better impact toughness, irrespective of the welding process used. The SMAW joints exhibited superior mechanical and impact properties, irrespective of the consumables used, than their FCAW counterparts.     

Comparative Study on Processing Property Between CWW CO2 Gas Shielded Welding and SAW

 Cable welding wire (CWW) CO2 gas shielded welding is an innovative process arc welding with high efficiency, high quality and low consumption, in which cable wire is used as consumable electrode. CWW CO2 gas shielded welding and submerged arc welding (SAW) are used for contrast studies on processing property of high strength steel A36 used in ship structure. The results show that the shapes of weld seam, using CWW CO2 gas shielded welding and SAW, are good and no weld defect such as air hole, flaw, slag inclusion, incomplete fusion, lack of penetration and so on are found in the weld seam. Because the rotating of arc during CWW CO2 gas shielded welding process has a strong stirring effect on molten pool, the grain in the heat affected zone (HAZ) of the joints, using CWW CO2 gas shielded welding, is small. Tensile failure positions of joints by CWW CO2 gas shielded welding and SAW are all in the base metal, but tensile strength of CWW CO2 gas shielded welding joint is higher than that of SAW joint by an average of 2. 3%. The average impact energy of HAZ, using CWW CO2 gas shielded welding and SAW, is almost equal, but the average impact energy of the weld seam using CWW CO2 gas shielded welding is increased by 6%, and the average impact energy of the fusion line is increased by 7%. The 180° bending tests for the joints of CWW CO2 gas shielded welding and SAW are all qualified, and the joints hardness is all less than HV 355, but hardness of CWW CO2 gas shielded welding wire welding joint near the fusion line is obviously lower. It can be concluded that the properties of CWW CO2 gas shielded welding are better than those of the SAW joint, and CWW CO2 gas shielded welding is suitable for welding high strength steel A36 used in ship structure.     

Evaluation of Microstructure and Mechanical Properties of Laser Beam Welded AISI 409M Grade Ferritic Stainless Steel

 The microstructure analysis and mechanical properties evaluation of laser beam welded AISI 409M ferritic stainless steel joints are investigated. Single pass autogeneous welds free of volumetric defects were produced at a welding speed of 3000 mm/min. The joints were subjected to optical microscope, scanning electron fractographe, microhardness, transverse and longitudinal tensile, bend and charpy impact toughness testing. The coarse ferrite grains in the base metal were changed into dendritic grains as a result of rapid solidification of laser beam welds. Tensile testing indicates overmatching of the weld metal is relative to the base metal. The joints also exhibited acceptable impact toughness and bend strength properties.     

Microstructure,Tensile and Impact Toughness Properties of Friction Stir Welded Mild Steel

 Microstructure, tensile and impact toughness properties and fracture location of friction stir welded AISI 1018 mild steel are revealed in this paper. The 5 mm thick AISI 1018 mild steel plates were friction stir welded with tool rotational speed of 1000 rpm and welding speed of 50 mm/min with tungsten base alloy tool. Tensile strength of stir zone is higher (8%) when compared to the base metal. This may be due to the formation of finer grains in the weld nugget region under the stirring action of the rotating tool. The ductility and impact toughness of the joints are decreased compared to the base metal and this is due to the inclusion of tungsten particles in the weld region.     

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.     

Performance evaluation of 00Cr11NbTi perforated-plasma-arc-welded joint

Based on a 00Cr11NbTi 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.     

Evaluating the Properties of Dissimilar Metal Welding Between Inconel 625 and 316L Stainless Steel by Applying Different Welding Methods and Consumables

The current work was carried out to characterize welding of Inconel 625 superalloy and 316L stainless steel. In the present study, shielded metal arc welding (SMAW) and gas tungsten arc welding (GTAW) with two types of filler metals (ERNiCrMo-3 and ERSS316L) and an electrode (ENiCrMo-3) were utilized. This paper describes the selection of the proper welding method and welding consumables in dissimilar metal joining. During solidification of ERNiCrMo-3 filler metal, Nb and Mo leave dendritic cores and are rejected to inter-dendritic regions. However, ERSS316L filler metal has small amounts of elements with a high tendency for segregation. So, occurrence of constitutional super-cooling for changing the solidification mode from cellular to dendritic or equiaxed is less probable. Using GTAW with lower heat input results in higher cooling rate and finer microstructure and less Nb segregation. The interface between weld metal and base metal and also unmixed zones was evaluated by scanning electron microscopy and energy dispersive X-ray (EDX) analysis. Microhardness measurements, tensile test, and Charpy impact test were performed to see the effect of these parameters on mechanical properties of the joints.     

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。     

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。     

Dendrite Morphological Analysis on SMA,GMA, and PGMA Welding of Dissimilar 304LN Austenitic Stainless Steel and Micro-alloyed Steel

Dissimilar metal welding between the austenitic stainless steel and micro-alloyed steel was widely used in high-temperature applications in power stations and petrochemical plants. In the current research, the dissimilar metals between austenitic stainless steel and micro-alloyed steel have been joined by shielded metal arc welding (SMA), gas metal arc welding (GMA), and pulse gas metal arc welding (PGMA) processes. Welded samples of the aforementioned processes were subjected to comparative studies pertaining to the dendrite morphological characteristics. The study reveals that the process parameters affect the growth of dendrite arm because of the variation in the coefficient of thermal conductivity, expansion, and metallurgical incompatibility of the metals. In the PGMA welding process, the dendrite length decreases, while its width increases in all the locations of the weld by varying dimensionless factors ϕ (0.05, 0.15, and 0.25) and keeping its heat input as constant (Ω—11.2 kJ/cm). Among the welded joints, the PGMA weld joint comparatively exhibit shorter length (20 µm) and width (4 µm) of dendrite arm than the welded joints of the GMA and SMA processes. The change in the dendrite dimension is observed to be due to the variation in the dimensionless factor ϕ and the quantity of heat transfer to the weld (QT). The studies have been systematically planned in order to gain advanced scientific knowledge to establish superior technique for multi-pass PGMA welding of thick section of austenitic stainless steel to micro-alloy steel with respect to that used with conventional welding process.     

Comparison of microstructure and properties between joints of FSW and TIG 316L austenitic stainless steel

FSW and TIG were conducted on 316L stainless steel.Variation during microstructure and properties in joints obtained by different welding methods was studied.The results show that the effect of severe mechanical stirring and intense plastic deformation creat a fine recrystallized grain in the welding joint during FSW.As for TIG,the temperature of welding joint exceeds the melting point of welded material itself.The entire welding process belongs to the solidification of a small molten pool;and the microstructure of the joint takes on a typical casting structure.When the welding parameters were selected appropriately,the average ultimate tensile strength of FSW joints can reach 493 MPa,which is 83.6%of base metal;the average elongation is 52.1%of base metal.The average ultimate tensile strength of TIG joints is 475 MPa, which is 80.5%of base metal;the average elongation is 40.8%of base metal.The tensile test of FSW joints is superior to the TIG joints.The microhardness of FSW joint compared to base metal and TIG joint having a significant improvement,which arel95.5 HV,159.7 HV and 160.7 HV,respectively;grain refinement strengthening plays an important role in enhancing the microhardness.The electrochemical corrosion tests show that the joint of FSW 316L austenitic stainless steel has a good corrosion resistance.     

船用热轧钢板焊接性能研究

建立了热轧钢板焊接热影响区（HAZ）的连续冷却转变曲线（焊接CCT曲线）,以研究船用热轧钢板的焊接性能。根据所建立的焊接CCT曲线,选择了合理的焊接工艺对10mm厚的船用热轧钢板进行了手工电弧焊,并对焊后的焊接接头进行了宏观检验和X射线探伤、力学性能试验及冲击试验。借助金相显微镜和扫描电镜分析了CCT图中不同冷速条件下的显微组织和焊接接头的显微组织以及冲击断口形貌。试验结果表明：根据建立的焊接CCT曲线,所选择的手工电弧焊的焊接工艺是合理的,焊缝质量良好,焊接接头具有良好的综合性能。     

耐火耐候钢焊接性能及焊接材料的研究

重点介绍了武钢技术中心高层办公大楼用WGJ510C2耐火耐候钢(14 mm 、25 mm)2种规格钢板与WQ-1埋弧焊丝匹配试验研究.按照工程提出的焊接技术条件,对武钢二热轧生产的WGJ510C2钢进行了埋弧焊对接性能试验,内容包括接头常规力学性能试验、高温拉伸性能试验、金相组织与硬度试验、电化学腐蚀性能试验.试验结果表明,采用WQ-1焊丝加CHF101焊剂匹配焊接WGJ510C2钢2种规格试板,接头常温拉伸强度和高温拉伸强度均满足WGJ510C2钢技术条件要求.焊缝、熔合线和热影响区低温冲击功大于140 J,接头各区电化学腐蚀电位相近,具有优良耐腐蚀性能,焊接接头综合性能指标完全满足高层建筑用钢焊接技术要求.     

Q420GJ钢双丝埋弧焊接试验

通过双丝埋弧焊接工艺性能试验、焊接接头力学性能试验及组织结构分析等,对Q420GJ钢的焊接性能及相关组织结构进行了研究。结果表明:焊接接头综合力学性能优良,接头抗拉强度达到590MPa,焊缝-40℃冲击功平均值KV2达到119J;热影响区的韧脆转变温度在-30℃附近;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。     

Influence of FCA Welding Process Parameters on Distortion of 409M Stainless Steel for Rail Coach Building

The influence of flux cored arc welding (FCAW) process parameters such as welding current, travel speed, voltage and CO2 shielding gas flow rate on bowing distortion of 409M ferritic stainless steel sheets of 2 mm in thickness was discussed. The bowing distortions of the welded plates were measured using a simple device called profile tracer. An experimental regression equation was developed to predict the bowing distortion and with this equation, it is easy to select optimized process parameters to achieve minimum bowing distortion. It is revealed that the FCAW process parameters have significant influence on bead profile and the bowing distortion.     

Gas Tungsten Arc Welding of 316L Austenitic Stainless Steel with UNS S32205 Duplex Stainless Steel

In the present work, dissimilar welding between UNS S32205 duplex stainless steel (DSS) and 316L austenitic stainless steel (ASS) was performed by using gas tungsten arc welding and ER2209 filler at two different heat inputs (0.52 and 0.98 kJ/mm). Microstructures were characterized using reflected light optical microscope and scanning electron microscope. Micro-hardness and tensile properties were measured across the weld for both the heat inputs. The microstructure of the welded region was primarily austenitic (for both heat inputs) with Widmanstätten morphology. The grain size of the heat affected zone on DSS side was very large (~200 µm) for the high heat input sample with the presence of partially transformed austenite and acicular austenite. The precipitation of intermetallic phases and carbides was not observed for both the heat inputs. The proportion of ferrite in the weld metal (as measured by feritscope) was higher for the high heat input sample than the low heat input sample. During the tensile test, fracture occurred in 316L ASS base metal (because of its lower strength) in ductile manner. For high heat input welds, the impact tested sample showed the presence of fine spherical precipitates rich in Cr, Mn and Fe in the fracture surface of weld metal.     

Effect of Arc Welding Processes on the Weld Attributes of Type 316LN Stainless Steel Weld joint

The present study aims at understanding the effect of various arc welding processes on the evolution of microstructure, mechanical properties, residual stresses and distortion in 9 mm thick type 316LN austenitic stainless steel weld joints. Weld joints of type 316LN stainless steel were fabricated by three different arc welding processes which were commonly employed in the nuclear industry. All the weld joints passed radiographic examination. Microstructural characterization was done using optical and scanning electron microscope. Volume fraction of δ-ferrite was lowest in the A-TIG weld joint. The A-TIG welded joint exhibited adequate strength and maximum impact toughness values in comparison to that of weld joints made by SMAW and FCAW processes. The A-TIG weld joint was found to exhibit lowest residual stresses and distortion compared to that of other welding processes. This was attributed to lower weld metal volume and hence reduced shrinkage in the A-TIG weld joint compared to that of weld joints made by FCAW and SMAW processes which involved v-groove with filler metal addition. Therefore, type 316LN stainless steel A-TIG weld joint consisting of lower δ-ferrite, adequate strength, high impact toughness, lower residual stresses and distortion was suited better for elevated temperature service compared to that of SMAW and FCAW weld joints.