New methods of predicting dissimilar steel weld metal microstructures by Schaeffler Diagram

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Evaluation of Microstructure and Mechanical Properties in Dissimilar Austenitic/Super Duplex Stainless Steel Joint

To study the effect of chemical composition on microstructural features and mechanical properties of dissimilar joints between super duplex and austenitic stainless steels, welding was attempted by gas tungsten arc welding process with a super duplex (ER2594) and an austenitic (ER309LMo) stainless steel filler metal. While the austenitic weld metal had vermicular delta ferrite within austenitic matrix, super duplex stainless steel was mainly comprised of allotriomorphic grain boundary and Widmanstätten side plate austenite morphologies in the ferrite matrix. Also the heat-affected zone of austenitic base metal comprised of large austenite grains with little amounts of ferrite, whereas a coarse-grained ferritic region was observed in the heat-affected zone of super duplex base metal. Although both welded joints showed acceptable mechanical properties, the hardness and impact strength of the weld metal produced using super duplex filler metal were found to be better than that obtained by austenitic filler metal.     

Microstructure and mechanical properties of dissimilar welds between 16Mn and 304L in underwater wet welding

Dissimilar joint between 304L austenitic stainless steel and low-alloy steel 16Mn was underwater wet welded using self-shielded nickel-based tubular wire. Microstructure, mechanical properties and corrosion behaviour of dissimilar welded joints were discussed. Ni-based weld metal was fully austenitic with well-developed columnar sub-grains. Type II boundary existed between Ni-based weld metal and ferritic base metal in underwater welds similar to that in air welds. Major alloying elements distributed non-uniformly across the austenitic weld metal/16Mn interface. Maximum hardness values in wet welding appeared in a coarse-grained heat-affected zone at the 16Mn side, which possessed very low impact toughness. Underwater Ni-based welded joints fractured at Ni-based weld metal under tensile test. Ni-based weld metal had favourable corrosion resistance similar to 304L base metal.     

高锰钢与钢轨钢二次闪光对焊接头的组织和冲击韧性

通过工艺试验,力学性能检验以及光镜、电镜、Ｘ射线衍射、电子探针等湿微分析手段,对高锰钢与钢轨钢二次闪光对焊接头的组织形态和冲击韧性进行了系统研究,确定了接头各区的组织形态和冲击韧性的变化情况,并提出了高锰钢与钢轨钢二次闪光对焊时改善钢轨钢焊接热影响区冲击韧性的工艺措施。研究表明,利用过渡材料来实现焊接性差、万分和物理性能相差悬殊的高锰钢与钢轨钢的焊接是一种行之有效的工艺措施。     

EFFECT OF CARBON MIGRATION ON CREEP PROPERTIES OF Cr5Mo DISSIMILAR WELDED JOINTS WITH Ni-BASED AND AUSTENITIC WELD METAL

In this paper, the effect of carbon migration on creep properties of Cr5Mo dissimilar welded joints with Ni-based (Inconel 182) and Cr23Ni13 (A302) austenitic weld metal was investigated. Carbon migration near the weld metal/ferritic steel interface of Cr5Mo dissimilar welded joints was analyzed by aging method. Local creep deformations of the dissimilar welded joints were measured by a long-term local creep deformation measuring technique. The creep rupture testing was performed for Cr5Mo dissimilar welded joints with Inconel 182 and A302 weld metal. The research results show that the maximum creep strain rate occurs in the decarburized zone located on heat affect zone (HAZ) of Cr5Mo ferritic steel. The creep rupture life of Cr5Mo dissimilar welded joints with A302 weld metal decreases due to carbon migration and is about 50％ of that welded with Inconel 182 weld metal.     

Microstructure and Mechanical Behavior in Dissimilar SAF 2205/API X52 Welded Pipes

The welding of a duplex stainless steel SAF 2205 DSS(UNS 31803) and high strength low alloy steel API X52 by shielded metal arc welding process was conducted using two different filler metals,the duplex E2209 and austenitic E309 grade.The microstructures of the dissimilar metal joints have been investigated by optical microscopy,scanning electron microscopy,energy-dispersive spectroscopy(EDS) and X-ray diffraction.EDS analysis at the interface X52 weld metal showed an evident gradient variation of Cr and Ni between boundaries of fusion and type II,where the highest hardness value was recorded.Tensile strength and toughness values of the weld metal produced by E309 electrode are slightly higher than those of the weld metal produced by E2209 electrode.Potentiodynamic polarization tests of different regions of the welded joints evaluated in 3.5%NaCl solution exhibit a high corrosion resistance of both weld metals.     

Welding austenitic steel to copper with the defocused radiation of a fibre laser

Special features of producing butt welded joints between 12Cr18Ni10Ti austenitic steel and M1 copper by laser welding are investigated. Welding was carried out without filler or intermediate material. The defocused beam of the fibre laser, displaced to the austenitic steel, was used. The welded joints in dissimilar materials produced in the selected conditions were without defects and their strength was comparable with the M1 copper parent metal. The tensile tests and hardness measurements were carried out on the resultant welded joints. The microstructure of the welded joints was investigated and the transition zone was examined by chemical analysis.     

热输入对T4003/Q450NQR1异种钢焊接接头组织及性能的影响

采用奥氏体焊材ER309LSi-G焊丝对T4003铁素体不锈钢与Q450NQR1耐候钢异种钢进行两种不同焊接热输入的MAG焊接,通过显微组织和力学性能等试验,对两种焊接接头性能进行研究。结果表明:两种焊接接头均未发现缺陷,焊接接头性能较好。与0.82 kJ/mm热输入比较,0.62 kJ/mm热输入下的焊接接头冲击韧性及硬度较好,熔合线较窄,晶粒度较为细小,拉伸数值较高,更加适用于T4003铁素体不锈钢与Q450NQR1耐候钢异种钢焊接。     

Fatigue Crack Growth Behavior of Gas Metal Arc Welded AISI 409 Grade Ferritic Stainless Steel Joints

The effect of filler metals such as austenitic stainless steel, ferritic stainless steel, and duplex stainless steel on fatigue crack growth behavior of the gas metal arc welded ferritic stainless steel joints was investigated. Rolled plates of 4 mm thickness were used as the base material for preparing single ‘V’ butt welded joints. Center cracked tensile specimens were prepared to evaluate fatigue crack growth behavior. Servo hydraulic controlled fatigue testing machine with a capacity of 100 kN was used to evaluate the fatigue crack growth behavior of the welded joints. From this investigation, it was found that the joints fabricated by duplex stainless steel filler metal showed superior fatigue crack growth resistance compared to the joints fabricated by austenitic and ferritic stainless steel filler metals. Higher yield strength and relatively higher toughness may be the reasons for superior fatigue performance of the joints fabricated by duplex stainless steel filler metal.     

珠光体钢与奥氏体钢异种钢焊接材料的选择与应用

分析了珠光体钢与奥氏体钢异种钢的焊接性,介绍了焊接材料的选用原则、材料种类、工艺及工程中的应用.结果表明：该类异种钢焊接材料的选择原则是,尽量选用接近或高于奥氏体钢的高合金成分,而不是接近珠光体钢的成分;尽量避免焊缝中马氏体组织形成,保证接头获得良好的使用性能和焊接性.可供该类异种钢选用的焊接材料种类较多,工艺方法各具特色.三个典型应用案例表明,这类异种钢焊接质量的有效控制,取决于焊接材料的合理选用及正确的工艺方法.新型、高效、自动化焊接材料是颇具推广应用前景的焊接新材料.     

Dilution and microsegregation in dissimilar metal welds between super austenitic stainless steel and nickel base alloys

Abstract

Super austenitic stainless steels are often welded using high Mo, Ni base filler metals to maintain the corrosion resistance of the weld. An important aspect of this processing is the weld metal dilution level, which will control the composition and resultant corrosion resistance of the weld. In addition, the distribution of alloying elements within the weld will also significantly affect the corrosion resistance. Dissimilar metal welds between a super austenitic stainless steel (AL-6XN) and two Ni base alloys (IN625 and IN622) were characterised with respect to their dilution levels and microsegregation patterns. Single pass welds were produced over the entire dilution range using the gas tungsten arc welding process. Microstructural characterisation of the welds was conducted using light optical microscopy, scanning electron microscopy, and quantitative image analysis. Bulk and local chemical compositions were obtained through electron probe microanalysis. The quantitative chemical information was used to determine the partition coefficients k of the elements in each dissimilar weld. The dilution level was found to decrease as the ratio of volumetric filler metal feedrate to net arc power increased. Reasons for this behaviour are discussed in terms of the distribution of power required to melt the filler metal and base metal. In addition, the segregation potential of Mo and Nb was observed to increase (i.e. their k values decreased) as the Fe content of the weld increased. This effect is attributed to the decreased solubility of Mo and Nb in austenite with increasing Fe additions. Since the Fe content of the weld is controlled by dilution, which in turn is controlled by the welding parameters, the welding parameters have an indirect influence on the segregation potential of Mo and Nb. The results of the present work provide practical insight for corrosion control of welds in super austenitic stainless steels.     

304/Q235复合板多主元高熵化焊缝的组织与性能

对304/Q235复合板进行激光填粉焊接试验,利用光学显微镜、扫描电镜、X射线衍射、材料万能试验机及电化学工作站等,对比分析了多主元高熵化CrNi₂MnTi_0.5Al_0.5焊料及Fe基焊料所得焊接接头的微观组织、物相结构、力学性能与电化学腐蚀性能,探索了焊缝填充材料对不锈钢复合板焊缝微观组织、接头性能的影响规律。结果表明,CrNi₂MnTi_0.5Al_0.5焊料焊缝区形成了FCC及Ti₃Al颗粒的双相结构,焊缝显微硬度仅为Fe基焊料焊缝区硬度的69%~75%。两种焊接接头都有较好的抗拉强度,拉伸试样都在母材区断裂。CrNi₂MnTi_0.5Al_0.5焊料焊缝区具有最佳的耐蚀性能,其腐蚀速率约为304不锈钢的41%。     

Fe_3Al合金与A304钢的TIG焊试验研究

采用TIG焊方法,分别选择9Cr-1Mo钢焊丝、A347焊丝和Inconel82Ni基合金焊丝作填充材料对Fe3Al合金与A304不锈钢进行焊接试验,并对接头质量进行了检测分析。结果表明:三种填充焊丝的焊缝中均有裂纹产生,并且在Fe3Al合金的热影响区还出现了微裂纹;采用Cr-Mo钢焊丝时,溶池金属沿Fe3Al母材基体结晶长大,接头区组织较均匀,而采用Ni基焊丝时,Fe3Al侧存在界线明显的熔合区。     

Fe3Al合金与A304钢的TIG焊试验研究

采用TIG焊方法，分别选择9Cr-1Mo钢焊丝、A347焊丝和Inconel82Ni基合金焊丝作填充材料对Fe3Al合金与A304不锈钢进行焊接试验，并对接头质量进行了检测分析。结果表明：三种填充焊丝的焊缝中均有裂纹产生，并且在Fe3Al合金的热影响区还出现了微裂纹；采用Cr—Mo钢焊丝时，溶池金属沿FeAl母材基体结晶长大，接头区组织较均匀，而采用Ni基焊丝时，Fe3Al侧存在界线明显的熔合区。     

Selection of filler wire for and effect of auto tempering on the mechanical properties of dissimilar metal joint between 403 and 304L(N) stainless steels

Weldability of the dissimilar weld joint between austenitic 304L(N) stainless steel (SS) and martensitic 403 SS made by gas tungsten arc welding process using ERNiCr-3 filler metal has been studied. For this study, 12 mm thick plates of these two materials were joined using a K-type weld groove joint, with the straight edge on the 403 SS side buttered using ERNiCr-3 filler wire. Two types of weld joints were prepared—one using as-buttered 403 SS and the other one with buttered and post-weld heat-treated 403 SS plate. The joint made with the as-buttered 403 SS plate exhibits good bend ductility and toughness on the heat-affected zone (HAZ) of the 403 SS side and it is comparable with that of the buttered and post-weld heat-treated 403SS weld joint properties. Thus, buttering of the 403 SS plate enabled dissimilar welding with the 304L(N) SS plate without any post-weld heat treatment because of auto tempering of the martensite present in the 403 SS HAZ formed due to weld thermal cycle.     

Effect of lattice matching degree and intermetallic compound on the properties of Mg/Al dissimilar material welded joints

The welding of Mg/Al dissimilar materials with different filler metal was investigated, and the quantities and kinds of intermetallic compounds were discussed. In addition, the matching degrees between base metal and intermetallic compounds were defined and calculated, and the effect of different quantities of each intermetallic compound on the property of welded seam was investigated. The results indicated that the welded seam was composed of Al₃Mg₂ and Al₁₂Mg₁₇ by Mg/Al directly gas tungsten arc butt welding, and only one intermetallic compound of MgZn₂ formed in the welding seam using Zn and Zn–xAl filler metal. The tensile strengths of the joints increased with the increase of the matching degrees between the intermetallic compounds and the base metal when the welded seam contained different intermetallic compound. Meanwhile, the tensile strengths of the joints are decreased with the increase of intermetallic compound content when the welded seams contained the seam intermetallic compound.     

高强钢CO2激光-MAG复合焊接性能

为了研究CO₂激光-熔化极活性气体保护焊（MAG）复合焊接性能,采用CO₂激光和CO₂激光-MAG复合焊接590MPa级高强度钢,对其焊接接头的显微组织和力学性能进行了研究.结果表明,激光-MAG复合焊接的焊缝金属中,MAG电弧作用区主要为珠光体和贝氏体,激光作用区主要为马氏体;激光-MAG复合焊接的焊缝金属中Mo和Mn合金元素的分布具有不均匀性;激光和激光-MAG复合焊接的试件焊接接头拉伸性能完全满足要求,焊缝强度高于基体强度;激光-电弧复合焊缝金属在-60℃～+15℃试验温度范围内的冲击韧性比激光焊缝金属高;激光-MAG复合焊接焊缝金属硬度在250～400 HV之间,高于基体金属的硬度.     

Fe-Cr-2Al-Si阻尼合金与1Cr18Ni9Ti不锈钢的钨极氩弧焊接

采用钨极氩弧焊（GTAW）和奥氏体不锈钢焊丝LNT309LSi作为填充金属,研究了Fe-Cr-2Al-Si阻尼合金和1Cr18Ni9Ti不锈钢的焊接工艺和焊接质量。借助金相显微镜分析了焊缝组织特征,采用电子探析分析了焊缝成分。按照国家标准研究了焊接接头的硬度、拉伸性能和弯曲性能。结果表明,用奥低不锈钢焊丝焊接Fe-Cr-2Al-Si阻尼合金和1Cr18Ni9Ti不锈钢,可获得理想的奥氏体＋少量的铁素体＋马氏体的焊缝组织,焊缝的抗拉强度和抗弯性能均高于阻尼合金。所采用的焊接方法、焊接工艺和焊丝能满足这两种钢的焊接要求,焊接质量可靠。     

预置镍基合金片对异种钢UNGW接头组织及性能的影响

研究了预置镍基合金片对15CrMo/1Cr18Ni9Ti异种钢超窄间隙焊接接头组织及性能的影响。结果表明,预置镍基合金片厚度小于0.6 mm时,15CrMo熔合线附近焊缝区部分区域以A模式凝固并形成奥氏体胞状晶,而其它区域仍以FA模式凝固,其组织为等轴晶奥氏体+枝晶状铁素体,并且焊缝中心无凝固裂纹形成。预置0.9~1.2 mm厚的镍基合金片时,焊缝中心因镍偏聚而以A模式凝固,形成粗大的奥氏体柱状枝晶,并有凝固裂纹形成。预置镍基合金片厚度在0.6~0.9 mm时,可使15CrMo熔合线附近焊缝区的Ni质量分数比填充金属(ER347L)的提高约2%,明显比未预置镍基合金片的接头具有更好的抑制碳扩散效果,但当镍基合金片厚度在0.3~1.2 mm范围内变化时接头抑制碳扩散的效果并无明显变化。焊态的异种钢接头不均匀混合区内存在马氏体层,而热时效后在熔合线附近会形成一定宽度的富碳硬化区及贫碳软化区。     

Das Verhalten von Unter-Pulverschweißnähten in Meerwasser

Behaviour of submerged arc welds in seawater Some examples are used to demonstrate the importance of the correct selection of base metal and the corresponding filler material. In the case of a high strenght, pearlite free fine grain steel welded with the filler metal S2Mo under basic powder the base metal is preferentially attacked; in view of the low corrosion loss however, this material can be considered safe for use in seawater containing oxygen. In welded systems of fine grain steel St 38 with increased Mn content, however, the potential of the weld seam obtained under identical welding conditions is clearly lower than that of the base metal, so that such welds must be considered unsuitable for use in sea water. The corrosion susceptibility was determined in a solution of 1% artificial seawater in 99% methanol.