Effects of welding wire composition and welding process on the weld metal toughness of submerged arc welded pipeline steel

The effects of alloying elements in welding wires and submerged arc welding process on the microstructures and low-temperature impact toughness of weld metals have been investigated. The results indicate that the optimal contents of alloying elements in welding wires can improve the low-temperature impact toughness of weld metals because the proeutectoid ferrite and bainite formations can be suppressed, and the fraction of acicular ferrite increases. However, the contents of alloying elements need to vary along with the welding heat input. With the increase in welding heat input, the contents of alloying elements in welding wires need to be increased accordingly. The microstructures mainly consisting of acicular ferrite can be obtained in weld metals after four-wire submerged arc welding using the wires with a low carbon content and appropriate contents of Mn, Mo, Ti-B, Cu, Ni, and RE, resulting in the high low-temperature impact toughness of weld metals.

Arc characteristics of submerged arc welding with stainless steel wire

The arc characteristics of submerged arc welding （SAW） with stainless steel wire were studied by using Analysator Hannover （AH）. The tests were carded out under the same preset arc voltage combined with different welding currents. By comparing the probability density distribution （PDD） curves of arc voltage and welding current, the changes were analyzed, the metal transfer mode in SAW was deduced, and the characteristics of a stable arc were summarized. The analysis results show that, with an increase of welding parameters, the short-circuiting peak in the PDD curves of arc voltage decreases gradually until it disappears, and the dominant metal transfer mode changes from flux-wall guided transfer to projected transfer and then to streaming transfer. Moreover, when the PDD curves of arc voltage are both unimodal and generally symmetrical, the greater the peak probability and the smaller the peak span, the more stable the arc becomes.

Research on submerged arc welding wire for X100 pipeline steel

According to the study of the microstructure and properties of X100 pipeline steel, the welding consumable-wire based on Mn-Ni-Mo-B-Ti alloy system was successfully designed and developed. The yield strength of the deposited metal of the developed welding wire was 695 MPa, the tensile strength was 810 MPa, and Charpy impact energy was 92 J at negative 20 ℃ when matching with BSG-SJ101H1 sintered flux. The results of the weldability test for X100 pipeline steel which adopting this developed wire showed that the tensile strength of the weld was 827 MPa, 185 J of Charpy impact energy（ -10 ℃ ） , 97% of section of shear and the weld had good strength and toughness matching when the welding speed got to 1.7 m/min. The microstructure and fracture appearance of the weld were analyzed by using metallographic microscope, scanning electron microscope （SEM） and laser confocal microscope, the results indicated that the microstructure was mainly granular bainite in the weld metal, and the fracture was dimple with 200 - 300 μm depth presenting a typical ductile fracture characteristics. The test of welding wire with different content of Ni and Cr element indicated that Ni was better than Cr in improving the strength and toughness of weld metal.

Inclusion behavior and microstructure of weld metal with Ce in twin wire high heat input submerged-arc welding

In this study,the welding thermal cycle curve exhibited two temperature peaks in high heat-input twin-wire separate-pool submerged-arc welding and coarse-grained heat affected zone existed in the welded joint. The inclusions of primary weld metal and coarse-grained heat affected zone of Ce-added SAW should be Al_2O_3,MnO,SiO_2,TiO,Ce_2S_3,CeS,Ce_2O_2S and Ce_2O_3. Under the effect of welding thermal cycle,oxy-sulfides inclusions of Ce,the diameter of which was less than 2. 0 μm,slightly grew larger,but the composition and type of the inclusions didn't change. The microstructure of the large heat input weld metal had acicular ferrite that Ce oxide sulphide particles induced nucleation and proeutectoid ferrite. In the coarse-grained heat affected zone of weld metal,home-position precipitation of acicular ferrite and sympathetic acicular ferrite were both observed. It was supposed that previous crystal cells of acicular ferrite in austenite grain promoted home-position precipitation of acicular ferrite. Meanwhile,sympathetic acicular ferrite tended to nucleate at the primary acicular ferrite grain boundaries,where high dislocation density was located,and grew inside the neighboring carbon-depleted austenitic regions. The granular bainite nucleated in the austenitic zone with high carbon content close to acicular ferrite and sympathetic acicular ferrite.

Prediction of cooling time t8/5 in twin wire submerged arc welding of intermediate thickness plate

Twin wire submerged arc welding （SAW） is widely used in oil or gas line pipe fabrication because of its high productivity. To investigate the strength and toughness of the heat-affected zone （HAZ） in twin wire SAW, the cooling time t8/5 of the coarse grained zone must be studied. The authors presented a method of predicting the cooling time in twin wire SAW of intermediate thickness plate. Based on Rosenthal analytical solutions, an energy factor was introduced to describe the energy contribution of the two wires, equations of thermal cycle and cooling time in twin wire SAW of both thick, and thin, plates were developed. Weighting factors determined by actual thickness and critical thickness were adopted to represent the thermal cycle and cooling time of intermediate thickness plate through linear interpolation with thick, and thin, plate solutions. The predicted cooling time for an intermediate thickness plate was verified experimentally, and the predicted results agreed therewith.

Research and engineering application of the arc welding pulsed controller technology

The tenacity of heat-affected zone （HAZ） will decline and the size of grains will increase, because of the overheating on HAZ when submerged are welding （SAW） is ased to thick plate with high heat input. The shaping will worsen when SAW is used to thin plate with high current at high speed. A new SAW technology, the pulsed direct current （DC） automatic SAW, will be put forward in this paper in order to overcome the above shortcomings. And a pulsed controller with micro-controller unit （MCU） as the core, nixie tube （NT） and keyboard as the man-machine conversation interface is developed. The main functions of the pulsed controller include the output of pulsed welding current and the working with twinwire. The research has widely prospects in application with significant meanings in theory and practical engineering.

基于SYSWELD的大厚板窄间隙双丝埋弧焊热过程数值模拟

基于60 mm厚Q345R钢,开展了窄间隙双丝埋弧焊焊接试验,得到了合理的工艺参数,焊缝成型平整均匀无任何缺陷.通过SYSWELD有限元软件对大厚板窄间隙双丝埋弧焊焊接热过程进行数值模拟分析,模拟的熔池宽与高和实际相比,误差率均控制在5%以内,并利用热电偶装置测得热影响区热循环曲线与模拟的热循环曲线变化趋势基本一致,具有升温快,降温慢的特点,验证了该模型的有效性.为后续利用该模型,进一步探究不同参数或边界条件对于大厚板窄间隙双丝埋弧焊焊接热过程与应力-应变规律提供理论指导.

厚板双面四丝单道埋弧焊接工艺参数设计及应用

结合焊缝熔深与四丝单道埋弧焊一丝焊接参数、钢板壁厚、坡口深度的函数关系,及焊丝填充面积与四丝单道埋弧焊一丝~四丝焊接参数、坡口深度、坡口角度的函数关系,设计厚板双面四丝单道埋弧焊接的焊接坡口尺寸及对应的焊接参数。依据此参数进行32 mm、40 mm和50 mm厚板双面四丝单道埋弧焊接试验。结果表明,设计的焊接工艺参数既可保证厚板大钝边尺寸双面焊接焊透,又能保证厚板大坡口截面填满,并可获得良好的焊接质量。

实-药芯多丝电弧复合焊中药芯焊丝位置对焊接稳定性的影响

为了实现高强钢的优质高效焊接,提出了一种全新的Q960E高强钢的高效焊接工艺,即实-药芯多丝电弧复合焊工艺,该工艺通过一把集成式三丝焊枪实现两根实心焊丝复合一根药芯焊丝,既可以利用药芯焊丝实现焊接接头力学性能的优化,又可以利用3根焊丝实现高效焊接。其中药芯焊丝可以从两实心焊丝的正前方、正后方及侧面送入,通过对比分析焊接过程、焊道成形得出最佳药芯焊丝作用位置,并对最佳药芯焊丝作用位置下焊接接头的组织和显微硬度展开分析。结果表明:当药芯焊丝从正后方或侧面送入时,其中一根实心焊丝易与熔池接触发生短路过渡,前者会导致焊道宽窄不一,后者会导致焊道明显偏向药芯焊丝送入一侧。当药芯焊丝从正前方送入时,药芯焊丝呈一脉多滴过渡,且两实心焊丝均为一脉一滴过渡,此时焊接过程稳定,焊后焊道成形较好,焊道横截面形貌呈“双峰”状,是最佳的药芯焊丝送入位置。此外,当药芯焊丝从正前方送入时,焊缝区组织主要为细小的针状铁素体,粗晶区组织主要为粗大的板条马氏体和少量粒状贝氏体,细晶区组织主要为细小的马氏体,不完全淬火区组织主要为回火马氏体。此外,热影响区同时出现了软化和硬化现象,近不完全淬火区的母材硬度最低,仅为296 HV,完全淬火区硬度最高,达到396 HV,母材和焊缝区的硬度在320~340 HV之间。

12Cr2Mo1V钢凸台附加填充丝埋弧堆焊工艺研究

针对12Cr2Mo1V钢加氢反应器壳体凸台采用单丝埋弧焊进行堆焊、制造效率低的问题,研究了采用附加填充丝埋弧焊的焊接方法堆焊12Cr2Mo1V材质凸台本体的工艺可行性。研究结果表明,在12Cr2Mo1V钢上采用附加填充丝埋弧焊进行本体堆焊,焊接工艺性良好;其工艺评定试验的各项力学性能完全满足母材的要求,特别是-30℃夏比KV_(2)型缺口冲击试验冲击值均≥54 J,抗回火脆化倾向评定试验结果均满足v Tr54+3Δv Tr54≤0℃的要求。与单丝埋弧堆焊相比,两枪六丝附加填充丝埋弧堆焊凸台可提高生产效率200%~250%。该项工艺研究在满足加钒钢凸台性能的前提条件下,能极大缩短凸台制造周期、节能减排,为加氢反应器先进绿色制造的发展提供了新的制造手段。

海上风电项目大厚板焊接工艺研究

对海上风电项目大厚板焊接工艺进行研究,选择可适应大线能量的焊材、母材,采用双丝埋弧焊的焊接形式,有效控制焊接参数,得到性能优良的焊缝。通过现场实际应用,验证了这种焊接形式的可靠性,为海上风电项目大厚板的焊接提供了可靠的工艺,可以指导现场进行生产。

压力容器用埋弧焊丝钢H10Mn2-A盘条冶炼及轧制实践

根据客户特殊需求开发了压力容器用埋弧焊丝钢H10Mn2-A盘条,为了保证低倍组织质量,通过LF精炼进行窄成分和气体含量控制,连铸全程保护浇注,过热度≤30℃,拉速2.2 m/min。为了获得优良的成品力学性能,采用控轧控冷工艺,开轧温度1000±20℃,吐丝温度890±10℃,辊道速度15 m/min。经客户试用,H10Mn2-A盘条强度适中、塑性好,易拉拔,冲击韧性良好,满足压力容器用焊丝的拉拔和焊接性能要求。

双丝埋弧自动焊技术在辽宁清原抽水蓄能电站压力钢管环缝焊接中的应用

抽水蓄能是技术较成熟、经济性较优、具备大规模开发条件的电力系统,具有绿色低碳、清洁灵活的电力系统调节电源。抽水蓄能电站不仅具有比常规水电站更高的内水压力,而且其工况转换会带来频繁的水锤作用。因此,抽水蓄能电站输水系统压力钢管的钢材,须采用具有良好的可焊性、低温稳定性、塑性和抗冲击韧性的低合金钢和高强调质钢。焊接工序是压力钢管制造、安装生产中的一道关键工序,需要充分考虑降低焊接成本,加快焊接速度,提升焊接质量,以此来满足在抽水蓄能电站建设过程对于技术方面高效优质的要求。随着科学技术的飞速发展,焊接技术也在与时俱进,埋弧焊接技术已从单丝发展到双丝和多丝。结合双丝埋弧焊接的原理、特点,立足辽宁清原抽水蓄能电站2.8万t压力钢管制造过程,对双丝埋弧自动焊接技术在压力钢管环缝焊接中的应用进行分析总结,以供参考。

LNG储罐用高锰低温钢埋弧焊焊接材料及工艺研究

研制出适用于LNG储罐用高锰低温钢配套的埋弧焊丝和焊剂。采用C-Mn-Cr-Ni-Mo合金体系设计,形成的焊缝金属中Mn含量为22.5%~25.5%,焊缝金属抗拉强度和-196℃低温冲击等力学性能优良,与奥氏体高锰低温钢匹配性良好。通过分析道间温度和热输入对熔敷金属力学性能的影响,结果表明,在焊接奥氏体高锰低温钢时,须控制好道间温度和采用较小的热输入,确保焊缝金属具有优良的综合力学性能。

碎焊丝+摆动埋弧焊接技术研究及PCTC船的应用

介绍了大间隙坡口碎焊丝+摆动埋弧焊的焊接方法在PCTC船甲板搭载焊接中的工艺技术研究及应用。通过对碎焊丝+摆动埋弧焊的碎焊丝铺设厚度、装配大间隙进行打底封焊和盖面的焊接工艺进行试验及研究,从工艺性能及力学性能方面进行探讨。结果表明,在采用合理的焊接工艺条件下,此工艺的焊接性能良好,焊接接头力学性能等亦能满足船级规范要求。与传统FCAW+SAW的焊接方法进行对比可知,此工艺的整体焊接效率提高了55%,且焊接质量稳定。

海上风机基础用S355NL直缝焊管双丝埋弧焊工艺设计

S355NL细晶粒结构钢以其优异的性能在海上风电、石油平台、焊接钢管等方面得到广泛应用。为进一步提高焊接钢管的生产效率,获得性能优良的海上风机基础用钢管焊接接头,开展S355NL直缝焊管的焊接工艺研究。采用双丝埋弧焊方式,选用低镍合金焊材,不仅能够细化焊缝组织晶粒,同时降低淬硬倾向,提高S355NL直缝焊管焊缝的低温冲击韧性。在焊接过程中采用多层多道焊接,控制热输入≤5.0 kJ/mm,减少熔合区和热影响区在高温区域停留时间,保证熔合线和热影响区冲击性能。试验结果表明,该工艺所制试板及成品焊管各项力学性能试验合格,能够满足-40℃夏比冲击试验要求。生产应用表明,该焊接工艺制定及焊材选配正确恰当,能够提高焊接生产效率。

高强高韧性管线钢埋弧用焊丝的研制

研制的高强高韧性管线钢用埋弧焊丝与SJ10 1和SJ10 2焊剂匹配后的熔敷金属不仅具有很高的强度 (σs≥ 5 4 0MPa) ,而且还具有优良的低温韧性 (AKv - 1 0℃ ≥ 12 0J)。该焊丝的研制满足了屈服强度超过 5 0 0MPa以上管线钢对焊缝熔敷金属性能的要求。研究结果表明 ,要保证熔敷金属具有较佳的强韧性匹配 ,熔敷金属中的合金元素总量必须满足Ceq≥ 0 .38,Pcm≥ 0 .17,才能保证熔敷金属的强度 ,以及具有以针状铁素体为主焊缝组织 ;在文中的合金系统下 ,随着熔敷金属中C、Mn元素含量的增加 ,熔敷金属的针状铁素体组织的含量增加 ,韧性得到提高。随着焊剂碱度值的增加 ,熔敷金属中的氧含量降低 ,C、Mn元素增加 ,使得熔敷金属中的合金元素更趋向于最佳的配比 ,从而提高了韧性。

高效埋弧焊技术的发展及应用

埋弧焊具有熔敷率高、焊接质量好等优点,是当今焊接生产中普遍使用的熔焊方法之一。介绍了多丝埋弧焊、带极埋弧焊、添加合金粉末埋弧焊、窄间隙埋弧焊、冷丝和热丝填丝埋弧焊等多种高效埋弧焊方法,并就各自的工艺特点、国内的应用情况进行了分析与总结。

高铬铸铁耐磨堆焊埋弧药芯焊丝研究

采用自动埋弧堆焊对高铬铸铁埋弧药芯焊丝堆焊合金的组织及耐磨性进行试验,研究Cr/C对堆焊层的组织和耐磨性的影响。研究发现,Cr/C增加,初生碳化物形状越来越规则,初生碳化物的杆状纤维增长,增加堆焊层的韧性。初生碳化物微区Cr含量增加,增加初生碳化物显微硬度。Cr/C与初生碳化物面积分数对耐磨性的影响比较明显,其中初生碳化物面积分数与耐磨性呈线性关系。高铬铸铁堆焊层的耐磨性受到基体组织影响较大,由奥氏体及其分解产物构成的混合基体的堆焊层耐磨性最大。文中所研究的41#、43#、45#焊丝其堆焊层的耐磨性非常好,相对Q235钢的耐磨性分别为β41=27.1716、β43=18.6305和β45=19.7949。文中进一步探讨了耐磨堆焊层磨损过程中的孔洞效应及裂纹扩张效应。

桥梁钢Q370q双丝埋弧焊研究

以新型桥梁钢Q370q为研究对象,采用埋弧焊丝H10Mn2、CJQ-4分别进行双丝埋弧焊接试验,同时采用埋弧焊丝H10Mn2进行单丝埋弧焊接试验,通过对焊丝H10Mn2的双丝、单丝埋弧焊焊接接头以及焊丝H10Mn2、CJQ-4的双丝埋弧焊接接头进行对比研究,对每种接头在化学成分、微观组织、力学性能等方面的差异进行了理论分析。结果表明,双丝埋弧焊接桥梁钢Q370q在选择埋弧焊丝CJQ-4时,力学性能满足相关技术标准要求,焊接质量良好。