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.

Self-Adaptive Control System for Additive Manufacturing Using Double Electrode Micro Plasma Arc Welding

Wire arc additive manufacturing(WAAM)has been investigated to deposit large-scale metal parts due to its high deposition efficiency and low material cost.However,in the process of automatically manufacturing the high-quality metal parts by WAAM,several problems about the heat build-up,the deposit-path optimization,and the stability of the process parameters need to be well addressed.To overcome these issues,a new WAAM method based on the double electrode micro plasma arc welding(DE-MPAW)was designed.The circuit principles of different metal-transfer models in the DE-MPAW deposition process were analyzed theoretically.The effects between the parameters,wire feed rate and torch stand-off distance,in the process of WAAM were investigated experimentally.In addition,a real-time DE-MPAW control system was developed to optimize and stabilize the deposition process by self-adaptively changing the wire feed rate and torch stand-off distance.Finally,a series of tests were performed to evaluate the control system’s performance.The results show that the capability against interferences in the process of WAAM has been enhanced by this self-adaptive adjustment system.Further,the deposition paths about the metal part’s layer heights in WAAM are simplified.Finally,the appearance of the WAAM-deposited metal layers is also improved with the use of the control system.

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.

M弧电流对Tri-Arc双丝电弧焊熔滴过渡形态影响

采用高速摄影技术对三电弧双丝电弧焊的熔滴过渡和焊接飞溅进行观察,分析金属型药芯焊丝在M弧电流变化时熔滴过渡的类型及飞溅产生的原因.结果表明,M弧电流为170 A时熔滴过渡形式有排斥过渡、颗粒过渡及细颗粒过渡,熔滴过渡不稳定.M弧电流为210 A时前丝和后丝熔滴过渡为大熔滴排斥过渡,三电弧同时出现,熔滴过渡稳定.M弧电流为260 A时前丝熔滴过渡为细颗粒过渡,后丝熔滴过渡为颗粒过渡,熔滴过渡较稳定.焊接飞溅产生的原因主要是脉冲切换改变了电弧力、斑点力及等离子流力,打破了原来的力系平衡.

U肋全熔透焊接正交异性板构造疲劳性能试验研究

为研究U肋与钢桥面不同焊接工艺接头的疲劳性能,以主跨408 m的中承式连续钢桁拱桥——武汉汉江湾桥主桥为背景,在传统单面埋弧焊基础上,提出一种先平位内焊再船位外焊的双面埋弧全熔透焊接技术,制作不同焊接工艺U肋与钢面板试件,开展丁字接头弯曲疲劳试验、焊接接头拉伸疲劳试验及3种典型构造细节疲劳试验,分析U肋与钢面板构造细节疲劳性能。结果表明:不同焊接方式下U肋与钢面板的疲劳强度差异明显,埋弧焊丁字接头的疲劳强度较高,大于342 MPa。U肋与钢面板双面埋弧熔透焊试件轴向拉伸状态下最低疲劳强度121.6 MPa,在-50~50 MPa拉-压循环应力幅和100 MPa拉应力幅下试件均未开裂;在120 MPa拉应力幅下,疲劳开裂加载次数均大于200万次,顶板内侧焊缝焊趾发生疲劳开裂。U肋与钢面板双面埋弧全熔透焊接构造细节疲劳性能优于单面焊及不开坡口的双面焊部分熔透构造细节,可以提高结构的耐久性和使用寿命。

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。

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。

工艺参数对原油船用耐蚀钢DWSAW焊接接头的影响

论述前后丝模式、焊接电流、焊接电压和焊接速度对国产原油船用耐蚀钢双丝埋弧焊(Double Wire Submerged Arc Welding,DWSAW)焊缝成型的影响,开展耐蚀钢DWSAW工艺试验,分析耐蚀钢DWSAW焊接接头的力学性能和耐腐蚀性能。结果表明,国产原油船用耐蚀钢具有良好的DWSAW适应性,采用合适的焊接工艺可获得力学性能和耐腐蚀性能兼顾的焊接接头。

Tri-arc双丝电弧焊堆焊工艺研究

采用三电弧双丝电弧焊,利用耐磨堆焊Fe-Cr-C-B系药芯焊丝作双丝,在Q235钢表面制备不同焊接工艺参数堆焊层,分析堆焊层熔合比、组织结构及耐磨性。结果表明:三电弧双丝药芯电弧焊堆焊可在较大范围调整焊接参数,获得较小的焊缝熔深、较低稀释率和较高的熔敷效率,耐磨性优异;当三电弧电流为150 A、电压30 V、焊丝伸出长度15 mm、送丝速度6 m/min、脉冲频率70 Hz时,堆焊层熔合比为0.07,堆焊层HRC为65,磨损量最小,耐磨性优良。

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。

石油化工油气管道焊接接头断裂韧性评定

评定了石油化工油气管道焊接接头断裂韧性,为今后石油化工油气管道质量提升、改进提供全新的研究思路。选取壁厚15,20,25 mm的石油化工油气管道常用X80等径管材,使用熔化极气体保护焊与双面多丝埋弧焊相结合的焊接方式,分别制备AJ-1,AJ-2,AJ-3 3种焊接接头试验试件。使用CTOD断裂韧性分别测定3个试件焊缝中心、熔合线、热影响区的裂纹顶端张开位移,并使用扫描电子显微镜观察各试件断裂微观形貌,分析各试件断裂韧性受裂纹扩展量影响情况。试验结果显示:裂纹扩展量会导致焊接接头裂纹顶端张开位移增大,影响焊接接头的韧性。3种焊接接头试件的不同区域裂纹顶端张开位移均>0.15 mm,断裂韧性较高;微观形貌结果显示,壁厚为15 mm的试件AJ-1热影响区韧窝较小,且出现较大解理面,脆性与韧性断裂特征都较为明显,该试件在焊缝中心与熔合线的韧窝较小,断裂韧性较低;壁厚为20 mm的试件AJ-2在热影响区存在准解理形貌,断裂韧性降低。在焊缝中心区的韧窝斜拉区断裂韧性升高,在熔合线出现较多剪切唇,断裂韧性并不理想;壁厚为25 mm的试件AJ-3在焊接接头各个区域均出现较多大韧窝,尤其焊缝中心的韧窝中出现第二相粒子,证明试件AJ-3的断裂韧性最高。