热输入对双光束激光焊接Ti-6Al-4V合金T型接头焊接过程、焊缝成形、组织及力学性能的影响（英文）

采用双光束同步激光填丝焊接的方法制备了Ti-6Al-4V合金T型接头,使用高速摄像机拍摄了焊接过程图像并研究了热输入对焊接过程稳定性、焊缝成形、组织及力学性能的影响。试验结果表明,热输入显著影响熔池行为和填丝焊接熔滴过渡,进而影响T型接头焊缝形貌及质量。随着热输入的增加,T型接头组织发生变化,晶粒尺寸变大。热影响区及焊缝处的马氏体使得这2个区域的显微硬度高于母材。另外,沿蒙皮方向及筋条方向的抗拉伸强度随着热输入的增加而增大。由于接头处马氏体增强作用,拉伸断裂均发生于母材处。     

40mm高强钢窄间隙激光填丝焊接头组织与性能

采用窄间隙光纤激光填丝多道焊的方法焊接了40 mm厚Q345D船用钢板,利用光学显微镜、扫描电镜和拉伸试验机分析了接头组织与性能。结果表明,选取合适的窄间隙激光填丝焊工艺可以得到成型好、无气孔和未熔合等缺陷的焊接接头,焊缝由13层构成,每层堆高约3 mm,焊缝宽度约为3.5 mm。填丝焊缝组织主要为铁素体和粒状贝氏体,焊缝中心冲击韧性良好。热影响区主要为马氏体组织,填丝焊的最高硬度值均出现在焊接热影响区,随着热输入的增加,热影响区最高硬度增加。拉伸试样均断于母材,焊接接头具有良好的力学性能。     

Ti-6Al-4V合金T型接头双光束激光焊接焊缝成形、组织及力学性能（英文）

采用双光束双侧同步填丝焊接的方法制备Ti-6Al-4V合金T型接头,并对焊缝成形、组织、力学性能及其相互关系进行研究。结果表明,试验获得了质量良好的焊缝,未出现不连续、焊瘤、可见的裂纹及气孔等缺陷,同时发现其与焊接过程中稳定的熔池行为及良好的熔滴过渡有关。从接头截面可以发现,蒙皮及筋条侧热影响区的形状完全不同。热影响区和熔合区的组织包含针状马氏体α′相。热影响区及熔合区的显微硬度均高于母材,且在筋条侧靠近融合区的热影响区处显微硬度最大。沿蒙皮及筋条方向的拉伸试样均断裂于母材处,其断裂方式为延性断裂。     

热输入对LNG运输车储罐用9Ni钢埋弧焊接头组织和性能的影响

通过埋弧焊的方法,采用三种线能量对22mm厚的9Ni钢板进行对接焊,对焊接接头金相组织进行观察,并对接头进行拉伸、弯曲、冲击、硬度等试验检验。结果表明,采用三种线能量的埋弧焊接头粗晶区组织均为马氏体,不完全正火区组织为回火马氏体和少量奥氏体,随着热输入的增加马氏体板条粗化;三种线能量的埋弧焊接头拉伸、弯曲性能均合格,随着线能量的增加,接头抗拉强度基本没有影响,而焊缝和热影响区-192℃冲击功均降低,且焊接热输入对HAZ冲击韧性影响比焊缝大;硬度测试结果表明,焊缝和热影响区硬度值均明显高于母材,临近母材的热影响区边界处均出现一个软化区,随热输入的增加,焊缝及热影响区最高硬度均提高,而软化区硬度几乎不变。     

焊接热输入对Q890/Q550异种钢激光-MAG复合焊接头组织及力学性能的影响

采用激光-MAG复合焊进行了Q890/Q550异种钢焊接试验,研究不同焊接热输入对异种钢焊接接头显微组织和力学性能的影响。试验结果表明,在相同热输入下,焊缝两侧过热区主要由板条马氏体和少量贝氏体组织组成,细晶区为致密的板条马氏体组织,Q890钢侧的马氏体含量比Q550侧多,板条更加粗短,焊缝冲击断口具有剪切韧窝特征,冲击韧性优于热影响区;随着热输入从3.5 kJ/cm增加到9.6 kJ/cm,过热区晶粒粗化,贝氏体逐渐增多,马氏体含量减少,焊缝和热影响区冲击吸收能量略微减小。三种热输入下拉伸试件均断在母材Q550钢,断后伸长率相当,断裂方式为韧性断裂,焊接接头强度高于母材。     

TC4钛合金窄间隙激光填绞股焊丝焊接接头组织及性能

采用实心绞股焊丝,通过窄间隙激光填丝焊对TC4钛合金进行焊接,分析了激光填丝焊接头各区域的微观组织及形貌,并测试了焊接接头的显微硬度、室温拉伸性能及冲击性能等力学性能。结果表明,焊缝截面整体成形良好,无明显未熔合和气孔等缺陷;母材由等轴α+β相组成,热影响区晶粒比母材稍大,热影响区由针状α′马氏体+初生α相组成,焊缝由粗大的原始β柱状晶和内部网篮状α′马氏体组成;焊接接头的抗拉强度平均值达940 MPa,拉伸断裂在母材,断口韧窝较浅,主要表现为韧性断裂特征;焊缝的显微硬度平均值为375 HV,高于母材及热影响区。 创新点： 采用高熔敷效率的绞股焊丝作为填充金属,对 20 mm 厚 TC4 钛合金板进行激光填丝焊,探究了厚板钛合金焊接接头的组织与性能分布规律,为厚板钛合金焊接结构的实际应用提供基础数据支撑。     

低活化马氏体钢激光焊接工艺与性能研究

研究了不同激光焊接工艺下低活化马氏体钢的焊缝形貌、显微硬度、常温拉伸和-40℃冲击性能,并对冲击断口形貌进行了观察。结果表明,当焊接热输入分别为1.2、1.4和1.8 k J·cm~(-1)时,低活化马氏体钢焊接接头均未出现未焊透现象。随着焊接热输入的增加,焊接接头上下表面的焊缝熔宽均呈逐渐增加的趋势。不同焊接热输入下,焊接接头的抗拉强度和屈服强度都明显高于低活化马氏体母材,且断裂位置都在母材处,而断后伸长率与母材相当。焊接热输入为1.4和1.8 k J·cm~(-1)时,焊缝区-40℃冲击功略高于基材,而热影响区-40℃冲击功与母材相当。     

大厚度TC4钛合金超窄间隙激光填丝焊接头组织性能研究

采用激光填丝焊接方法进行96 mm厚TC4钛合金板超窄间隙焊接,并对焊接接头进行了组织和性能分析。研究发现:焊缝整体呈钉形,没有出现气孔、裂纹及侧壁未熔合等焊接缺陷;焊缝区域主要由大量细长针状α’马氏体相互交织构成;焊接接头上中下3部分热影响区宽度、焊缝区域中α’马氏体板条宽度和位错密度呈递减趋势;焊接接头下部焊缝区域的α’马氏体晶界取向差在55°~65°的大角度晶界分布较中部和上部焊缝区域组织中略少一些;上中下3部分焊接接头中的焊缝区域显微硬度均明显高于热影响区和母材;沿壁厚方向焊接接头的抗拉强度与母材相当,焊接接头断裂位置均位于硬度值较高的焊缝处;最大局部应变出现在焊接接头下部中靠近母材的焊缝区域,局部应变值达到26.3%,而最小的局部应变值出现在焊接接头上部靠近母材的焊缝区,局部应变值约为14.5%。     

T91/P91窄间隙热丝TIG焊接工艺对接头力学性能的影响

通过对T91/P91窄间隙热丝TIG焊试验,对比研究了焊接接头各区包括焊缝、热影响区、母材的显微组织,以及各项力学性能比如常温拉伸、高温拉伸、硬度及冲击性能,从而探究窄间隙热丝TIG焊对T91/P91钢焊接性的影响.试验结果表明,焊接接头组织均匀,主要为回火马氏体;抗拉强度达到了母材水平甚至比母材更强;焊缝区域硬度分布比较均匀,硬度值高于热影响区和母材;焊缝的冲击韧性也与母材相当.研究结果表明,窄间隙热丝TIG焊可以改进T91/P91焊接接头的焊接质量,焊接接头各项力学性能均满足使用需求,从而获得了较高质量的焊接接头.     

铝硅镀层钢激光填丝焊接接头组织和性能

对铝硅镀层热成形钢进行激光填丝焊接试验,研究填充焊丝对焊接接头显微组织、力学性能及拉伸失效机制的影响. 结果表明,在激光自熔焊条件下,焊缝中平均Al元素含量为1.90%(质量分数),显微组织为马氏体和粗大的δ铁素体,焊接接头抗拉强度和断后伸长率分别为1 340 MPa和1.80%,因δ铁素体与马氏体之间存在显著的硬度差(142 HV),拉伸时裂纹源于δ铁素体和马氏体之间的相界面. 在激光填丝焊条件下,焊缝平均Al元素含量降低至0.96%,由于填充焊丝对铝的稀释作用使得焊缝为全马氏体组织,焊接接头抗拉强度和断后伸长率分别提升至1 510 MPa和4.4%. 因填充焊丝同时对焊缝中的碳也有稀释作用,焊缝中马氏体硬度(491 HV)低于母材中马氏体(523 HV),拉伸时裂纹于马氏体内部萌生并扩展,最终断裂于焊缝.     

Ti-6Al-4V合金双光束激光焊接T形接头拉伸过程特征

采用双侧同步激光焊接的方法获得Ti-6Al-4V合金T形接头，借助红外热成像的方法，研究激光焊接T形接头拉伸过程中典型缺陷如咬边、未熔合、气孔等的影响及特征. 结果表明，拉伸过程中温度的升高虽然出现在两侧蒙皮母材中，但随着变形量的增加，接头咬边处的应力集中效应凸显，温度也在该区域出现了大幅上升，塑性变形增大，并最终在此处发生断裂. 未熔合及气孔缺陷一般处于硬化区中部，不影响该区域的强化作用，温度的大幅增加仍位于蒙皮一侧母材处，最终在温度最高点处发生断裂.     

Microstructure and Mechanical Properties of Pulsed Laser Beam Welded Ti-2Al-1.5Mn Titanium Alloy Joints

The microstructure and mechanical properties in the pulsed laser beam welded joints of Ti-2Al-1.5Mn titanium alloy thin sheet were investigated in this study. The results show that the original α + β-phases and the transformed α + α′-phases are found in the partially transformed heat-affected zone (HAZ) together with the remaining β-phase, and the microhardness gradually enhances in the region as the result of the increase of α′-phase. The martensitic α′-phase and the remaining β-phase are detected in the fully transformed HAZ and the fusion zone (FZ), and the highest microhardness is found in these regions in virtue of the dominant α′-phase structure. The fine α′-phase appeared in the FZ results in higher average microhardness at high welding speed. Moreover, similar to the results of microhardness test, the tensile test results mean that the HAZ and FZ are stronger than the base metal (BM). Therefore, pulsed laser beam welding is feasible for joining thin sheet of Ti-2Al-1.5Mn titanium alloy.     

电子束焊接热输入对Ti-24Al-15Nb-1.5Mo/TC11双合金焊接接头组织和显微硬度的影响

利用OM,SEM,能谱分析和显微硬度等测试方法对Ti-24Al-15Nb-1.5Mo/TC11双合金焊接接头的显微组织特征及硬度进行了分析.结果表明,焊接热输人为135 kJ/m时,焊缝熔合区柱状晶由均匀密集的α'相针状马氏体和少量α相组成,显微硬度平均值为447 HV.焊接热输入增大到150 kJ/m时,熔合区α'相明显减少,焊缝TC11合金侧热影响区的短针状α+β组织变为粗大的长针状组织,Ti-24Al-15Nb-1.5Mo热影响区的β晶粒变得更粗,显微硬度平均值降为402 Hv.这主要是因为增大热输入使焊缝合金元素含量的比例发生变化,并且冷却速度下降使焊缝组织形态和分布改变,最终导致显微硬度降低.合金元素Ti,Al,Nb的含量在焊缝边界发生突变,但在焊缝熔合区达到一个新的平衡.

Abstract：

Microstructure evolution characterization of the Ti-24Al-15Nb-1.5Mo/TC11 dual alloys welded joints obtained on the condition of different electron beam heat input was studied by optical microscope, scanning electron microscope, energy spectrum and micro-hardness analysis. The results show that the energy input have an important effect on the microstructure, grain size, micro-hardness and alloy elements content of welded joints. The microstructure is made up of homogeneous acicular martensite α' phase in fusion zone (FZ) and the average micro-hardness value is 447HV when heat input E = 135 kJ/m is utilized. With heat input increasing to 150 kJ/ m, the number of α'phase decreases in FZ, short acicular α + β phase become coarser in heat-affected zone(HAZ) of TC11, coarse β grains become larger in HAZ of Ti-24Al-15Nb-1.5Mo and the average micro-hardness value drops to 402HV. The result is attributed to the changed content of alloy elements and lower cooling velocity caused by increasing heat input. The content of element Ti, Al and Nb is changed abruptly in the boundary of the joint, but these elements evenly distribute in each zone and hardly diffuse.     

激光焊接热输入对Ti2AlNb合金组织性能的影响

研究激光焊接热输入对Ti-22Al-27Nb(at%)合金焊缝成形和力学性能的影响,利用OM、SEM、XRD和TEM等手段对焊接接头的显微组织特征进行了分析,并探讨了焊后热处理对焊接接头组织性能的影响。结果表明,连续激光焊接可以获得无缺陷、成形良好的焊接接头。焊缝区域组织主要为柱状的B2相,柱状晶的生长方向垂直于熔合线。焊缝和热影响区的显微硬度要高于母材,焊缝的平均显微硬度最高。随着热输入的增加,焊接接头的室温抗拉强度增加,但是焊接接头的延伸率较低。焊接接头650℃高温强度为母材的71%~75%,塑性则仅为母材塑性的40%左右。经过焊后热处理,焊缝由B2+O相组成。O相增多使得焊缝的室温强度略有提高,且提高了650℃高温拉伸性能,高温抗拉强度最高可达母材的87.5%。     

The MPAW of Ti-3Al-2.5V Thin Sheets and Its Effects on Mechanical and Microstructural Properties

This research work deals with joining of Ti-3Al-2.5V titanium alloy thin sheets by means of microplasma arc welding (MPAW). An experimental set-up was developed to produce specimens welded in butt joint under controlled welding parameters, such as voltage, current, travel speed, and shielding gas flow rate. The performance of MPAW process was examined by mechanical properties tests and microstructural characterization. Results show that tensile strength and elongation of the welded specimens for a range of specific input heat are comparable to those of the base material (BM). Scanning electron microscopy (SEM) images of the fracture surface presented characteristics of ductile rupture. Studies on microstructure morphology of the specimens at the fusion zone (FZ) and heat-affected zone (HAZ) reveal occurrence of phase transformation from high temperature β phase to acicular $ \alpha^{\prime} $ phase, while the BM is of equiaxed α with intergranular β. An increasing variation in hardness was measured at the HAZ and FZ, which can be attributed to the presence of acicular $ \alpha^{\prime} $ phase and decreasing the amount of β phase at these regions. Based on the experimental results, it can be stated that MPAW process is an effective method for joining Ti-3Al-2.5V thin sheets provided appropriate welding parameters are used.     

Thermal cycle and its influence on the microstructure of laser welded butt joint of 8 mm thick Ti-6Al-4V alloy

Ti-6Al-4V alloy is extensively used in the manufacture of components in aviation. In the current study, the laser welding process is adopted to joint the Ti-6Al-4V alloy plate which has the thick of 8 mm. A three-dimensional finite element model is established to simulate the temperature distribution of laser welding process. The thermal cycle curves are produced on the strength of the simulation results. Meanwhile, the microstructure characteristics of the welded joint are investigated combined with simulation results. The results show that weld zone, heat affected zone and based metal experience similar thermal cycles process and the cooling rate has an important influence on the formation of microstructure. Moreover, the simulation results are well matched with experiment results.     

细晶粒钛合金GTAW焊缝成形性能分析

通过常规及细晶粒Ti-6Al-4V钛合金的GTAW试验,对比了不同焊接工艺时两种钛合金的焊缝成形.结果表明,由于细晶钛合金晶粒细化,晶界增多,而使热导率降低,焊接过程中晶界对热量传导的阻碍作用变大,这就使得细晶粒钛合金的焊接参数范围变窄,在很大的电流参数范围内,细晶粒钛合金的焊缝成形性能均比常规钛合金差很多;但是在一个较窄的电流变化围内,细晶钛合金的焊缝成形性能优于常规钛合金,超出此范围,成形较差;并讨论了可能的影响因素;针对文中的试件规格推荐了一个最优的焊接电流参数为47～48 A.

Abstract：

Fine grain titanium alloy is used extensively in aerospace and ailrraft because of its excellent comprehensive properties and outstanding machinability. Fine grain Ti-6Al-4V alloy and common grain Ti-6Al-4V alloy were welded by tungsten iner-gas arc welding( GTAW) respectively. Welding parameters and appearance of two Ti-6Al-4V alloys welded were investigated. The results indicate that the heat conductivity impediment of grain boundary strengthened because of fine grain Ti-6Al-4V alloy grains refinement and grain boundary increasing. Thus, its coefficient of heat conductivity is decreasing . Camparing with appearance of common grain Ti-6Al-4V alloy, when the range of welding current parameter was wide, the appearance of fine grain Ti-6Al-4V alloy was bad. However, when the range of welding current parameters was narrow relatively, the appearance of fine grain Ti-6Al-4V alloy welded was better than the one of common grain Ti-6Al-4V alloy. The possible influencing factors were discussed. At last, according to the specimen size, an optimal welding current parameter(47 ～ 48) A was recommended.     

送丝速度对Ti-3Al-6Mo-2Fe-2Zr钛合金激光填丝焊接头组织与性能的影响

采用Ti-6Al-4V(TC4)焊丝对2 mm厚的Ti-3Al-6Mo-2Fe-2Zr钛合金进行激光填丝焊接,利用光学显微镜、扫描电子显微镜、X射线能谱仪等分析测试方法研究了送丝速度对接头显微组织和力学性能的影响. 结果表明,由于从熔合线至母材受到焊接热作用逐渐递减,热影响区组织依次为单一β相、基体β相 + 初生α_p相、基体β相 + 初生α_p相 + 少量次生α_s相. 焊缝中有针状α'相生成,且分布不均匀. 随着送丝速度的增加,针状α'相的数量增加,尺寸增大. 激光填丝焊接头的抗拉强度及断后伸长率均低于母材,随送丝速度的增加,接头抗拉强度上升,断后伸长率下降.其原因在于TC4焊丝的加入,促使针状α'相在焊缝中析出,送丝速度加快,造成焊缝中钼当量[Mo]_eq降低,析出的针状α'相数量进一步增多,尺寸增大. 针状α'相的析出提高了焊缝强度,当送丝速度大于1.0 m/min时,接头的断裂位置为热影响区.     

激光焊接对SPF/DBTi-6Al-4V合金疲劳性能的影响

研究了SPF/DB Ti-6Al-4V合金及其激光焊接接头静态拉伸性能和疲劳性能,并获得S-N曲线.通过观察组织特征和疲劳断口形貌,分析了激光焊接对SPF/DB Ti-6Al-4V合金疲劳性能的影响.结果表明,SPF/DB T-6Al-4V合金激光焊接接头的抗拉强度略低于母材抗拉强度,而疲劳强度明显低于母材疲劳强度,约为其抗拉强度的40%.SPF/DB Ti-6Al-4V合金组织为α+β等轴细晶组织,其焊接接头组织为含α,针状马氏体α'和少量β相的魏氏组织结构.焊接接头组织结构的不均匀性,以及组织的粗大化是导致激光焊接接头疲劳性能下降的重要原因.SPF/DB Ti-6Al-4V合金疲劳断裂为塑性断裂,其焊接接头疲劳断裂为准解理断裂,这显著降低激光焊接接头的疲劳性能.而焊接气孔等焊缝表层微小几何不连续缺陷的存在往往成为激光焊接接头疲劳断裂的裂纹源.     

2A97铝锂合金激光焊T形接头组织及性能

采用异种模式与同步模式双光束DISK激光焊接1.5 mm厚的2A97-T3铝锂合金T形接头,对比研究两种模式T形接头的微观组织,硬度分布和拉伸性能.结果表明,两种模式接头的焊缝区显微硬度仅为母材的61%~67%,但异种模式接头深熔焊缝的显微硬度偏高,表明沉淀相的溶解使焊缝区出现软化,而热导焊过程对深熔焊缝有强化作用.异种模式T形接头蒙皮和桁条的抗拉强度分别为415和337 MPa,为母材的84.8%和68.9%;而同步模式分别达到母材的90.6%和59.4%.异种模式T形接头蒙皮和桁条拉伸均断在热导焊缝的过渡区,表明热导焊缝过渡区是异种模式T形接头最薄弱区域.