Laser welding of Zr53.7Ni9.4Cu28.5Al8.4 bulk metallic glass

采用激光焊接技术对Zr53.7Ni9.4Cu28.5Al8.4块体金属玻璃进行焊接试验,研究在激光焊接下不同工艺参量对焊接接头组织的影响,探讨了焊接热循环过程中焊缝和热影响区的晶化行为.结果表明,固定激光功率1200W,焊接速度从8m/min提高到30 m/min,均成功获得了无气孔和裂纹等缺陷的焊接接头.焊缝熔化区保持了非晶结构,热影响区则出现不连续的呈弧形分布的点状晶粒.随着焊接速度的提高,热影响区的晶粒尺寸逐渐减小.     

焊接速度对高强镀锌钢板激光焊接头组织和性能的影响

采用激光焊接的方法对1.5 mm厚的DOGAL 800DP高强度镀锌钢板进行对接焊,通过用金相显微镜对接头显微组织进行观察,用万能拉伸试验机对接头抗拉强度及伸长率进行测试,研究了焊接速度对其焊接接头组织和力学性能的影响。结果表明,焊缝组织主要为贝氏体+少量的先共析铁素体及侧板条铁素体,热影响区组织主要为板条马氏体+贝氏体,马氏体含量明显高于焊缝;随着焊接速度提高,焊缝中铁素体含量减少,马氏体含量增加,热影响区组织细化,接头抗拉强度和伸长率均先升高后降低,当焊接速度为0.8 m/min时强度最高,1.0 m/min时伸长率最大;焊接速度高于1.2 m/min或低于0.6 m/min都不利于获得力学性能优良的焊接接头,当焊接速度为1.0 m/min时,接头具有最佳强塑性匹配。     

中厚板6082铝合金激光-MIG复合焊工艺与力学性能研究

采用激光-MIG复合焊工艺对中厚板6082铝合金进行焊接,焊接完成后,对焊缝进行了显微组织观察、硬度测试以及拉伸性能检测。结果表明,当激光功率为4.5 kW,焊接速度为1.2 m/min,离焦量为5 mm,送丝速度为8 m/min时,焊缝表面成形良好;焊缝熔合区显微组织均为等轴枝晶,晶粒较小,热影响区较窄,并且焊缝上部的组织相较于焊缝下部较为细小密集;焊接接头的热影响区硬度较母材和焊缝中心最高;焊缝的平均抗拉强度为251.9 MPa,接近于母材。     

含铒铝合金激光焊接接头组织与性能研究

对含铒铝镁合金冷轧板进行了激光焊接,分析了接头的各区域的微观组织和力学性能,探讨了铒对焊缝及热影响区组织与性能的影响。结果表明:由于稀土元素Er的加入,使焊缝中心晶粒尺寸减小到30μm左右;熔合线附近出现"细晶层";热影响区晶粒未见明显长大;焊接接头焊缝截面的显微硬度呈W形分布;Er对焊接接头的抗拉强度提高并不明显,接头抗拉强度为母材的70%。     

Q345E钢激光-MIG复合高速焊工艺及接头力学性能研究

对6 mm Q345E钢开展激光-MIG复合高速焊焊接工艺试验,研究了不同焊接热输入对焊缝成形及接头力学性能的影响规律。研究结果表明:在保证焊接接头质量的前提下,最大焊接速度可达4.2 m/min;焊接热输入在4.4～2.1 kJ·cm~(-1)范围逐渐减小时,焊接接头角变形减小,当焊接速度4.2 m/min时,焊接角变形仅0.8°,与1.2 m/min焊接速度相比减小了57%。随着焊接热输入减小,焊接接头淬硬倾向增加,接头最高硬度出现在焊接热影响区,当焊接热输入为2.1 kJ·cm~(-1)时,接头的最高硬度最高,为600 HV;当焊接热输入减小时,焊缝金属组织由块状铁素体及下贝氏体向板条马氏体转变,焊接热影响区粗晶区出现大量板条马氏体,焊接热输入越小,马氏体晶粒越小。在不同焊接热输入下,焊接接头拉伸断口均断于母材。     

薄板TC4钛合金TIG电弧和激光焊接接头晶粒尺寸与微观组织

对薄板TC4钛合金进行TIG电弧和激光焊接技术研究,重点分析了TIG焊接电流、焊接速度和激光输出功率对TC4钛合金焊接接头晶粒尺寸、微观组织和显微硬度的影响规律. 试验结果表明,在实现薄板TC4钛合金完全熔透的条件下,激光焊接具有更小热输入,接头焊缝区和热影响区宽度也显著降低. TIG焊接接头晶粒尺寸随热输入增加,呈现增加趋势. 随距焊缝中心位置增加,焊接接头晶粒尺寸均逐渐降低. TC4钛合金激光焊接接头焊缝区呈现魏氏组织特征,针状α'马氏体细小. 近缝热影响区组织为网篮状α'马氏体,而近母材热影响区为未转变α相和针状α'马氏体的双相组织. 随距焊缝中心位置增加,马氏体生成量逐渐减少,焊缝显微硬度值呈现降低趋势;同时相比于TIG焊接,TC4激光焊接接头具有更高的显微硬度.     

薄板2524铝合金激光填丝焊接工艺及组织性能

2524铝合金是具有优异损伤容限的新型航空高强Al-Cu-Mg合金.采用高功率光纤激光器焊接1.6 mm厚2524铝合金,研究了填充5087焊丝情况下,激光功率、焊接速度和填丝速度对焊缝成形、热裂纹倾向和焊缝显微组织的影响,优化焊接工艺参数,考察接头静态拉伸性能.结果表明,采用填充材料后,焊缝柱状枝晶生长方向性明显减小、晶粒细化、晶界共晶增多、热裂纹倾向降低.当激光功率为2.5 kW,焊接速度为2 m/min,填丝速度为2 m/min时,可获得成形良好、无缺陷的焊缝,接头抗拉强度达到313~324 MPa,拉伸断裂于接头熔合线附近,断口处有大量韧窝,呈韧性断裂特征.     

激光焊接工艺对QAl11-6-6铜合金焊接接头显微组织的影响

采用金相显微镜、扫描电镜、能谱仪等分析手段研究了激光焊接工艺对QAl11-6-6铜合金焊接接头显微组织的影响。结果表明:焊接速度对焊缝的宏观形貌有较大的影响。焊接速度较低时焊缝及热影响区较大,而随着焊接速度的增加,焊缝变窄,但焊缝的熔透性变小。焊接速度为10 m/min时,由于热输入小、冷却速率大,焊缝区晶粒较细,其尺寸为5μm左右,且基本无氧化夹杂等缺陷;焊缝区的相组成主要为α相、β′相、K相,未发现γ2相的存在,因而可避免焊接接头出现脆性断裂。     

激光焊接快速凝固Ni51Ti49形状记忆合金显微组织和相变行为

文中研究了快速凝固Ni₅₁Ti₄₉形状记忆合金条(厚度1 mm)的激光焊接工艺,以及焊缝成形、接头显微组织演变、硬度分布和马氏体相变行为. 结果表明,激光功率和焊接速度对焊缝成形有显著影响,采用激光功率为700 W、焊接速度为8 mm/s的焊接工艺实现焊缝区完全熔透,并获得熔合面积适中、缺陷较少的高质量接头;激光焊接导致接头各区域呈现显著的组织不均匀性,其中母材区保留快速凝固工艺的细晶、强织构显微组织特征,热影响区为粗大等轴晶和柱状晶构成的混合晶组织,焊缝中心区为粗大的柱状晶. 激光焊接后热影响区和熔合区的维氏硬度相对母材有显著降低,其中熔合区的平均硬度最低,其值为311 HV ± 14 HV. 接头经500 ℃保温1 h无应力时效处理后,接头各区域组织的相变行为明显不同,其中冷却过程中母材区发生常规两步马氏体相变(B2–R–B19′),而焊缝区呈现多步马氏体相变行为,即先发生一步B2–R相变,随后发生两个独立的R–B19′相变.     

焊接速度对TRIP590钢激光焊接头组织性能的影响

利用金相、拉伸及硬度试验研究不同焊接速度对TRIP590钢激光焊接头组织结构及力学性能的影响。结果表明,接头热影响区(HAZ)组织主要由贝氏体、铁素体及残留奥氏体组成,焊缝区(WZ)主要由板条状马氏体组成,随焊接速度提高,马氏体板条更加细长,晶粒细化。接头宏观断裂发生在母材区,其抗拉强度与母材相当。接头焊缝区硬度达430 HV,约为母材2倍,随焊接速度提高,热影响区变窄,焊缝硬度增加。     

铜钢异种材料等离子弧焊接头性能

采用LHM-200等离子弧焊机对1 mm紫铜与低碳钢异种材料进行了熔透型等离子弧焊试验,得到了内部无缺陷、外观成形良好的接头.观察了接头的显微组织,并分析了工艺参数对接头力学性能的影响.结果表明,焊缝区中心显微组织呈细胞群状,界面两侧的组织特征呈现显著的不同,焊缝与铜侧界面没有明显的熔合线,局部呈漩涡状,钢侧与焊缝连接处出现了明显的分界线;最佳工艺为焊接电流为65 A,焊接速度为0.4 cm/s,离子气流量为0.7 L/min,此时接头抗拉强度可达176 MPa,试样断裂于铜母材热影响区.     

CO_2激光焊接600MPa DP钢接头组织与性能

采用CO2激光对抗拉强度为600MPa,厚度1.4mm的DP钢进行焊接.研究焊接速度对焊缝外观和截面成形的影响、接头的组织特点、硬度、强度和成形能力.结果表明,激光功率相同,焊接速度较低时焊缝易产生气孔,焊接速度较高时易发生飞溅;焊接速度对焊缝熔深及熔宽也有影响.焊缝区组织主要由马氏体构成,从焊缝、焊接热影响区到母材,组织中马氏体含量下降,接头的最高硬度出现在焊缝或热影响区.在平行于焊缝方向,焊接接头的抗拉强度高于母材,垂直于焊缝方向,接头的抗拉强度与母材相当.由于焊缝出现马氏体组织,接头的塑性和韧性降低,板材的冲压成形能力下降.     

TZM钼合金钨极氩弧焊工艺及焊接接头组织

针对TZM钼合金,研究了钨极氩弧(TIG)焊工艺中不同焊接电流对焊接品质的影响,分析了焊接接头的显微组织及性能。结果表明,当TIG焊焊接电流为210 A,焊接速度4 mm/s,氩气流量8～12 L/min时,可获得品质优良的焊缝。焊接接头组织主要由焊缝中心粗大的柱状晶及热影响区的等轴晶组成,取代了母材的片层状纤维织构,削弱了材料的强度,改善了材料的塑性。     

激光焊接头超塑变形组织表征

采用高温拉伸研究激光焊接头超塑性变形行为,分析了焊缝及热影响区在超塑性变形过程中的显微组织演变规律,并提出采用等轴化系数来表征焊缝组织的等轴化进程,采用平均晶粒尺寸来表征热影响区组织的转变程度.结果表明,随着变形的进行,等轴化系数逐渐升高;在相同变形量时,变形温度升高或初始应变速率降低均有利于等轴化系数上升,促进焊缝超塑性变形的进行.随着变形的进行,热影响区平均晶粒尺寸逐渐升高;在相同变形量时,变形温度升高或初始应变速率降低均有利于平均晶粒尺寸上升,促进焊缝超塑性变形的进行.     

00Cr18Ni14Mo2Cu2不锈钢耐海水腐蚀焊接工艺分析

研究了00Cr18Ni14Mo2Cu2奥氏体不锈钢耐海水腐蚀的焊接工艺,通过改进焊接工艺,减小了热影响区宽度,减少了热影响区与焊缝金属化学成分的差异,细化了热影响区金相组织,控制了热影响区σ相析出.结果表明,热影响区腐蚀速率减小,且焊接接头(焊缝、热影响区和母材三者同时暴露在腐蚀介质中)腐蚀速率明显减小,大大提高了该钢焊缝区域的耐海水腐蚀性能.     

A304不锈钢薄板激光焊接接头微观组织及电化学腐蚀研究

为了研究A304不锈钢薄板的连续激光焊接工艺及电化学腐蚀性能,本文采用英国GSI公司的JK2003SM型Nd：YAG固体激光器进行焊接实验,并对焊接接头微观组织进行了研究。研究结果表明工艺参数为P=1 600 W,v=3 mm/s,焊后熔宽为1.6 mm,焊缝的中心位置有等轴晶;A304不锈钢焊接接头耐蚀性最强的是焊缝金属区、其次是母材区、最弱的是热影响区。     

电站锅炉用HR3C新型奥氏体耐热钢的激光焊接

超(超)临界电站锅炉用新型铁素体、奥氏体耐热钢对传统焊接技术提出了挑战.激光焊接技术作为一种可靠高效的先进焊接方法,为此类钢的焊接提供了经济可行的解决办法.采用窄间隙激光填丝焊接技术,研究了10 mm厚HR3C新型奥氏体耐热钢管的激光焊接性,并对接头显微组织及高温持久强度进行了分析.试验采用3 500 W Slab CO2激光器,填充焊丝为T-HR3C.结果表明,通过优化激光焊接工艺参数,可以获得X射线探伤和渗透检验合格的焊接接头;焊缝具有明显的沿中心对称形态,以细小的柱状晶为主,混夹着少量细小的等轴晶;热影响区晶粒没有明显长大,焊缝与母材的显微硬度相当,没有明显的软化区;焊态下的激光焊接接头高温持久强度较固溶处理的热丝TIG焊接头有明显提高.     

Residual stress and microstructure in welds of 13%Cr–4%Ni martensitic stainless steel

The objectives of the present study were to characterize the distribution of residual stress and the microstructure changes induced by welding in the heat-affected zone (HAZ) of 13%Cr–4%Ni used in hydraulic turbine fabrication to deduce best practices. To characterize residual stress after welding, hole-drilling, X-ray diffraction (XRD) and the contour method were used on a FCAW 6 passes UNS W41036 (410NiMo) weld deposited on UNS S41500 (13%Cr–4%Ni) stainless steel; the results were put side to side with the weld microstructure and hardness to assess their criticality. Transverse compression was found in and around the last bead of the weld by XRD and hole-drilling. Longitudinal compression stress was found in and around the last bead while longitudinal tension was found near the low-temperature HAZ. The contour method showed that despite high compression in the last bead, high longitudinal tension exists in the rest of the weld and just below the weld. The superposition of both residual stress distribution and results from microstructural characterization shows that in multipass welding of 13%Cr–4%Ni martensitic stainless steel, cracking susceptibility is higher in the weld than in the HAZ, let it be fatigue cracking, environment-assisted cracking or cold cracking during welding. Post-weld heat treatment proved to be very efficient in lowering residual tension found in the first bead and in lowering the hardness of the weld. These results underline the importance of following proper procedures when welding these steels; this being even more true when the assembly is loaded in fatigue.     

Quantitative research on the heat affected zone of weave bead welding for Invaralloy

Quantitative research on the heat affected zone( HAZ) of weave bead welding( WBW) joint for Invar alloy is carried out in this paper. Based on the morphology and related data analysis of the weld seam,the width difference of each layer and the forming mechanism are analyzed. Results show that the bottom layer( Layer 1) has the widest HAZ and the smallest fluctuation,which reaches 1 200 μm. HAZ width of layer 2 to 5 is relatively narrower which is basically below 600μm,while the amplitude fluctuation is greater. The main reason lies in the welding path. The long straight welding without weave causes the base metal near the groove fully melts which causes by the long straight welding without weave,while welding with weave leads to the uneven and inadequate melting of metal near groove.     

Role of Welding Parameters Using the Flux Cored Arc Welding Process of Low Alloy Steels on Bead Geometry and Mechanical Properties

Welding parameters have direct effects on the bead geometry, microstructure, and mechanical properties of low alloy steels. A series of experiments have been carried out to examine some of these parameters using the flux cored arc welding process (FCAW). In this article, an experimental study was conducted to investigate the influence of welding parameters in FCAW process particularly welding voltage and travel speed on weld bead dimensions. The study also includes the effects of bead overlap and deposition sequence on the parent material and the heat-affected zone (HAZ) properties. It was found that an increase in the welding voltage leads to an increase in the weld bead width, and the increase in the welding traverse speed leads to a decrease in the weld bead width. When studying the bead overlap percentages, it was found that the 50% bead overlap can be considered to be practically a better option than the higher percentages of bead overlap (i.e., 70-90%). The experimental investigation of studying the deposition sequence showed that there were no significant differences in the microstructure, hardness, and the size of the refined HAZ between the two proposed deposition sequences. However, a significant improvement in the microstructure and the size of the refined HAZ, and a reduction in the hardness were achieved after depositing the second welding bead, irrespective of the depositing sequence.