1800 MPa热成形钢与CR340LA低合金高强钢激光焊接性能

采用光纤激光焊接设备对1800 MPa级热成形钢与CR340LA低合金高强钢进行对接激光拼焊,研究了不同激光焊接功率和焊接速度下焊接接头的组织演变规律及热冲压成形性能,并对焊接接头的力学性能和硬度进行了分析。结果表明,3种焊接工艺下激光拼焊原板综合力学性能相差较小,由焊接接头造成的伸长率和抗拉强度的损失均在母材的28.3%和9.1%以内。激光焊接后焊缝区均为粗大、高硬度的马氏体结构;两侧热影响区组织主要为铁素体和马氏体,接头未出现明显的软化区。激光拼焊原板拉伸试样均断裂于CR340LA母材区,距离焊缝12 mm左右,且存在焊缝隆起现象。选取焊接功率和焊接速率分别为4000 W和0.18 m·s?1的焊接试样在高温下进行热冲压成形检测,未出现焊缝开裂,热成形后拼焊板具有良好性能,满足汽车激光拼焊板使用要求,拉伸结果表明,试样断裂位置与未热冲压成形前一致,均位于CR340LA母材区,拉伸过程中,焊缝向高强度母材侧偏移,在弱强度母材侧产生应力集中并缩颈断裂。      

非调质预硬态塑料模具钢B30的焊补性能

研究比较了两种预硬态塑料模具钢－非调质钢B30和进口调质钢2738的焊补性能,发现B30钢焊接热影响区的硬度变化明显比2738钢小,即前者的焊补性能较好,在此基础上,利用三种不同焊材和五种不同焊接工艺进行了焊补试验,测定了焊缝到母材显微硬度的变化,从而确定了获得较均匀硬度分布的焊接材料是结构焊条J107Cr,相应的焊接工艺是350℃预热,350℃焊接及焊后350度回火。     

中温压力容器用钢15CrMoR焊接接头组织与性能研究

对60 mm厚度中温压力容器用钢15CrMoR进行埋弧焊接(SAW)试验，研究钢板焊态和焊后热处理态焊接接头的组织及性能。结果表明：焊态和焊后热处理态焊缝的组织均为针状铁素体+粒状贝氏体+先共析铁素体，粗晶区组织均为贝氏体，而细晶区组织稍有差别，其中，焊态细晶区组织为粒状贝氏体+铁素体+珠光体，焊后热处理态细晶区组织为粒状贝氏体，热处理前、后显微组织无显著变化。性能指标说明15CrMoR钢焊缝处强度高于母材，焊后热处理提高了焊接接头的低温冲击性能，降低了焊接接头硬度，具有较低的冷裂纹倾向，可焊性更好。     

电子束焊喷射成形Al-Zn-Mg-Cu合金的组织性能研究

采用电子束焊接的方法对10 mm厚的喷射成形Al-Zn-Mg-Cu合金板进行了拼焊实验。采用金相显微镜、扫描电镜、室温拉伸实验、显微硬度等方法分析了焊接接头的微观组织,测试了焊接接头的力学性能及显微硬度。结果表明,喷射成形Al-Zn-Mg-Cu合金焊接接头由三个区域(近缝区母材,焊核区,热影响区)组成。焊缝宽为0.3～1.0 mm,焊核区由尺寸约3～8μm的等轴细晶组成,析出相沿晶界分布,晶内析出相较少;热影响区大部分保留了母材的原始组织特征,小部分区域发生了重熔。从焊缝区到母材,显微硬度值逐渐下降,焊缝区硬度值高出母材约35。经T6处理后,焊接接头强度约为母材的82%。     

激光点焊接头力学性能与失效数值模拟研究

测试了三种形状的激光焊点在拉伸、剪切、剥离工况下的静态和动态力学性能,分析了点焊焊缝的显微组织特性和硬度分布情况。结果表明,焊点形状与焊点力学性能密切相关,C型焊点整体性能更优;焊点强度随加载速率的增加而发生塑性强化,加载速率越大,塑性强化越明显;焊缝整体分布均匀,过度平滑,融合区和热影响区硬度高。基于LS-DYNA焊核合力失效准则,研究了激光点焊接头失效数值仿真方法,明确了等效焊核直径用于模拟激光点焊失效方法的有效性。     

热冲压成形钢与双相钢点焊接头组织及显微硬度分析

本文以厚度为1.8 mm热成形钢T1500HS与厚度为1.3 mm的DP600钢板电阻焊点为研究对象,对其微观组织和显微硬度进行了测试分析.试验结果表明,从母材、热影响区到焊核区域,T1500HS侧的微观组织依次为:马氏体/回火马氏体/铁素体+马氏体/细晶马氏体/板条状马氏体;DP600侧微观组织依次为:铁素体+少量马...     

热处理对40CrNiMoA钢板焊接接头组织及力学性能的影响

本文研究了调质工艺对40CrNiMoA钢板焊接接头显微组织及力学性能的影响。试验结果表明,经 830 - 870 °C +550 - 650 °C 调质处理后,40CrNiMoA钢3 mm板90 A 10 V焊接接头的焊缝区、热影响区、母材区的硬度差异显著减小,形成了回火索氏体组织。调质处理温度越高,焊接接头的焊缝区、热影响区与母材区的组织越 均匀,且组织中的碳化物颗粒尺寸增大。40CrNiMoA钢焊接板经850 Y油淬,600 X.回火后,具有较高的强度(905 MPa)和塑性(13. 5% ),综合力学性能最优。     

TA1中厚板电子束焊接组织性能及接头强化原因分析

采用真空电子束焊对30 mm厚TA1工业纯钛试板开展焊接试验,结合光学金相显微镜(OM)、维氏硬度、拉伸试验及电子背散射衍射(EBSD)对接头进行宏微观组织性能检验,分析电子束焊接过程对TA1材料微观组织与力学性能的影响及接头强化原因.结果 表明:电子束焊接热循环过程使TA1母材至焊缝组织由等轴α向锯齿α转变;焊缝及热影响区的强度、硬度均高于母材;接头性能得到强化与锯齿α及针状α马氏体对硬度的提升作用、焊缝及热影响区内细小的锯齿状α晶粒以及微细孪晶对焊接组织的细化作用有关.     

焊后热处理对异种钢焊缝组织和性能的影响

选择高强钢和超低碳钢异种钢焊缝试样,进行不同温度的热处理,对比不同保温温度下焊缝区域的金相组织、力学、杯突和洛氏硬度等性能,研究保温温度对异种钢焊缝的影响。结果表明,900℃保温5min后,焊缝熔合度良好,焊缝强度较高,焊缝熔合区附近的组织较为细小;随保温温度升高,试样硬度呈下降的趋势,且热影响区的硬度比母材明显提高。     

1500 MPa热成形钢钢带激光焊焊后热处理工艺研究

采用HSL21型激光焊接机对1 500 MPa热成形钢钢带进行对接焊,对激光焊接头进行了不同温度下的焊后热处理,并进一步对接头杯突性能、显微组织及硬度进行了检验。结果表明,焊态接头杯突性能较差,焊缝及热影响区明显淬硬,平均显微硬度达500 HV0.2左右,显微组织为马氏体;随着热处理温度的提高,焊缝和热影响区的硬度值降低,杯突性能逐渐提高;500℃热处理时,焊缝区和热影响区组织为回火马氏体,在600℃和800℃热处理时,组织分别转变为回火索氏体和贝氏体。     

Weld metal ductility in aluminum tailor welded blanks

The objective of the research described in this article was to characterize and numerically describe the ductility of weld material in aluminum tailor welded blanks under uniaxial tension conditions. Aluminum tailor welded blanks consist of multiple thickness and alloy sheet materials welded together into a single, variable thickness blank. To evaluate the mechanical properties of the weld material in these tailor welded blanks, a series of tensile specimens containing varying ratios of weld and monolithic material in the gage area of the specimen were tested. These experimental results show that increasing the amount of weld in the cross-sectional area of the specimen decreases the ductility of the specimen and that the weld characteristics have a pronounced impact on ductility. Using the experimental results and classical tensile instability and necking models, a numerical model was developed to describe the ductility of the weld metal. The model involves basic material properties and an initial imperfection level in both the weld and monolithic materials. The specimens studied were produced from 1- to 2-mm AA5182-O aluminum alloy sheet material welded into blanks using an autogenous gas tungsten arc welding process.     

Characterisation of the Forming Behaviour of Patchwork Blanks

In order to satisfy the increasing demand for environmental sustainability and passengers’ safety, automotive manufacturers are more and more obliged to develop improved body concepts for lighter but also safer vehicles. At the same time, production costs have to be minimised in order to cope with the international market. Besides the application of new materials and innovative production processes mainly the use of tailor‐made semi‐finished products such as tailored welded blanks, tailored rolled blanks or tailored tubes can contribute substantially to this objective. Furthermore, for the production of sheet metal components with a load adapted material distribution, the patchwork blank technique represents a potential alternative to the widely‐used concept of tailored blanks. But even if patchwork blanks offer some additional advantages, this innovative technique has hardly found its way into series production due to a number of unsolved challenges regarding their formability and numerical modelling of corresponding forming processes. In this contribution the forming behaviour of welded patchwork blanks is investigated by means of experimental trials and finite element analyses. In order to simulate the forming processes of patchwork blanks accurately, knowledge about the characteristics of the weld metal, including the weld bead and the heat affected zone, is essential. For this purpose, Martens hardness measurements, which allow the analysis of the weld seam and the determination of the lateral extension of the heat affected zone, have been carried out. Subsequently, uniaxial tensile tests with longitudinally welded samples have been applied to characterise the constitutive behaviour of the weld metal. The results obtained from these experimental investigations have been implemented to different finite element models for patchwork blank forming processes. A comparison of the numerical results with experimental data obtained from a series of Nakajima tests allows a validation of the presented modelling techniques. It can be stated that the accuracy of the finite element analysis may be improved if the modified material properties along the weld seam are considered in the numerical model.     

含铝304和316L奥氏体不锈钢热轧板材焊接性能

 对加Al质量分数为4%的304、2%的316L不锈钢热轧板材的焊接性能进行了研究。采用手工氩弧焊（TIG）的焊接方法,利用光学显微镜对焊缝的显微组织进行分析,利用电子探针（EMPA）分析焊接母材的元素分布,并对焊接接头进行力学性能测试。组织和力学性能的研究结果表明：含铝304和含铝316L合金热轧板分别选用ER308L,ER316L作为焊接材料,经TIG焊接后,焊缝无裂纹、气孔等缺陷,接头具有良好的强度和塑性,焊接接头力学性能接近于其母材;热影响区组织与母材组织基本一致,焊缝与母材熔合良好,组织良好,加铝304和316L不锈钢具有良好的焊接性能。     

Study of welding ultra‐fine grained ferrite steel by CO2 laser

Ultra‐fine grained ferrite steels have higher strength and better toughness than the normal ferrite steels because of their micrometer or sub‐micrometer sized grains. In this paper the ultra‐fine grained steel SS400 is welded by CO₂ laser. The shape of weld, cooling rate of HAZ, width of HAZ, microstructures and mechanical properties of the joint are discussed. Experimental results indicate that laser beam welding can produce weld with a large ratio of depth to width. The cooling rate of HAZ of laser beam welding is fast, the growth of prior austenite grains of HAZ is limited, and the width of weld and HAZ is narrow. The microstructures of weld metal and coarse‐grained HAZ of laser beam welding mainly consist of B_L + M (small amount). With proper laser power and welding speed, good comprehensive mechanical properties can be acquired. The toughness of weld metal and coarse‐grained HAZ are higher than that of base metal. There is no softened zone after laser beam welding. The tensile strength of a welded joint is higher than that of base metal. The welded joint has good bending ductility.     

Evaluation of Microstructure and Mechanical Properties of Laser Beam Welded AISI 409M Grade Ferritic Stainless Steel

 The microstructure analysis and mechanical properties evaluation of laser beam welded AISI 409M ferritic stainless steel joints are investigated. Single pass autogeneous welds free of volumetric defects were produced at a welding speed of 3000 mm/min. The joints were subjected to optical microscope, scanning electron fractographe, microhardness, transverse and longitudinal tensile, bend and charpy impact toughness testing. The coarse ferrite grains in the base metal were changed into dendritic grains as a result of rapid solidification of laser beam welds. Tensile testing indicates overmatching of the weld metal is relative to the base metal. The joints also exhibited acceptable impact toughness and bend strength properties.     

Weldability Evaluation and Microstructure Analysis of Resistance‐Spot‐Welded High‐Mn Steel in Automotive Application

In this paper, resistance spot weldability of high‐Mn steels were investigated in order to get high reliability in welded joints of automotive components. Microstructural characterizations, cross‐tensile test (CTT), microhardness tests of spot welded parts were conducted. The effects of weld current on the microstructural characteristics, mechanical properties, and fracture modes were investigated using optical microscopy (OM) and scanning electron microscopy (SEM). The hardness in the weld nugget was observed to be lower than that in the base metal (BM). In CTT, the failure initiation was observed to occur at the boundary of the weld nugget. Also welding imperfections of welded parts were investigated. Liquation cracking in heat affected zone (HAZ), porosity, and shrinkage cavity were found most common welding defects in welded parts. Furthermore, the effects of welding imperfections on weld quality and failure criteria were identified and discussed.     

Laser Welding of Ultra-Fine Grained Steel SS400

Steeliswidelyusedbecauseofitsgoodcompre hensive properties ,plentyofresourceandlowerprice .Thestrengthandtoughnessaretwoimpor tantpropertiesofsteels ,andpeoplemakeeffortstoincreasetheirvalues .Addingalloyingelementandcontrollingmicrostructurearetwobasicwaystoac complishtheaim .Therefinedmicrostructureob tainedbyprocessingtechniqueenablesthestrengthandtoughnessofsteeltobeincreasedwithoutaddingalloyingelementandtheratioofperformance costtobeincreased .Theultra finegrainedsteelshavefer ritegrains…