石油储罐钢焊接热影响区模拟研究

采用焊接热模拟技术,研究不同焊接热输入条件下焊接热循环对石油储罐钢焊接热影响区粗晶区(CGHAZ)的组织和性能的影响.结果表明:实验钢在80～100kJ/cm的大热输入下,热影响区仍能够保持良好的低温韧性;随着焊接热输入的增加,实验钢CGHAZ组织变粗大,低温冲击功下降;钢中弥散分布着大量细小TiN粒子,在焊接热循环中...     

Zr微合金钢粗晶热影响区韧性和组织分析

为了获得大热输入焊接热影响区,利用实验室25 kg真空感应炉炼制不同Zr含量的实验用钢,在MMS-300型热模拟机上,对其试样进行热输入能量为100 kJ/cm,峰值温度1 400℃的大热输入焊接热模拟实验.借助电子探针(EPMA)等对CGHAZ中形成针状铁素体(AF)的夹杂物进行了微区分析,研究了夹杂物的化学组成和分布形态.结果表明:当Zr含量为0.003%时,焊接CGHAZ区低温冲击韧性最好,当Zr含量大于0.003%时CGHAZ的低温韧性随着Zr含量的增加呈下降趋势;CGHAZ中的奥氏体晶粒尺寸随小尺寸夹杂物数量的增加而降低;形成AF的夹杂物多以Zr的氧化物为核心表面析出MnS的复合氧化物夹杂,尺寸在0.5～3μm.     

铁素体不锈钢焊接HAZ的晶粒长大模型

用物理模拟方法研究了铁素体不锈钢EB26－1焊接热影响区HAZ的晶粒长大,通过在不同规范下的等温晶粒长大物理模拟与分析,并结合焊接试验,建立了HAZ晶粒长大的模型,该模型成功地将Arrhenius公式用于热影响区晶粒长大计算,给出了焊接HAZ存在很陡的温度梯度对晶粒大长起阻碍作用的热钉扎效应,为选择合适的焊接规范和计算机模拟提供了依据。     

中空45钢棒材摩擦焊接工艺研究

为了改善大直径中空45~#钢棒材的连续驱动摩擦焊接性,采用二级加压方法进行了外径42 mm,内径26 mm的45~#钢连续驱动摩擦焊接.试验结果表明,焊接热输入随着摩擦时间、旋转速度的增大而增大,当摩擦时间较短、旋转速度较低时,采用较大的顶锻力、二级摩擦力不能显著增加焊接热输入,导致无法顶锻,产生严重的焊接缺陷.对于无缺陷接头,接头最大强度系数达到80.9%,接头中未发现熔化现象,焊缝发生动态再结晶,热机影响区和部分正火区出现魏氏体组织.接头冲击试验发现,力学性能优异的接头薄弱区位于部分正火区,而焊接热输入较高的接头薄弱区位于热机影响区.焊接热输入较低难于获得缺陷的焊接接头,焊接热输入过大显著降低接头力学性能.     

焊接热输入对Q345R钢接头湿硫化氢应力腐蚀敏感性的影响

实际焊接过程中焊接参数会影响焊接热输入,进而影响焊接接头的显微组织和性能.为此,研究了一系列焊接热输入条件下Q345R钢焊接接头的显微组织及其在湿硫化氢环境中的应力腐蚀敏感性.结果表明:当焊接热输入从44.2 kJ/cm增加到49.7 kJ/cm时,铁素体晶粒增大;当焊接热输入达到55.3 kJ/cm时,焊缝区组织出现了针状铁素体;在湿硫化氢环境下慢应变速率拉伸,所有焊接热输入下的焊接接头均出现明显的应力腐蚀开裂,同时发现在相同浓度的湿硫化氢环境下,当焊接热输入从44.2 kJ/cm增加到49.7 kJ/cm时,焊接接头的应力腐蚀敏感性指数随之增大,当焊接热输入增大到55.3 kJ/cm时,由于焊缝区出现了针状铁素体,使其应力腐蚀敏感性得到缓解.     

Q235与400MPa超级钢焊接热影响区晶粒尺寸的预测对比

应用有限元方法建立了低碳钢与超级钢焊接温度场数学模型,分别对5mm厚低碳钢板和超级钢板等离子焊温度场和热循环进行了模拟和时比分析;利用模拟得到的热影响区热循环曲线,根据晶粒长大动力学原理分别对其热影响区晶粒尺寸进行预测。预测结果表明,低碳钢热影响区晶粒尺寸远大于超级钢热影响区晶粒。     

T91钢焊缝及热影响区显微组织图象分析

T91钢具有良好的高温抗氧化性和抗腐蚀性,该钢含8％－9．5％Cr,合金含量复杂,焊接难度大,运用金相显微镜和扫描电镜（SEM）分析了不同爆接工艺条件下T91耐热钢焊缝及热影响区或区域显微组织特征,利用XQF－2000型显微图象分析仪对显微组织中各相的相对含量和奥氏体晶粒度进行了测量,分析了焊接线能量对T91钢焊接接头区组织性能的影响,结果表明,采用多道焊焊接工艺,严格控制焊接线能量在16kJ/cm左右,可以防止T91钢焊缝区奥氏体晶粒粗大,避免在热影响区出现声状铁素体组织,从而保证焊接接头区具有良好的组织性能。     

高强钢焊接接头显微组织的研究进展

综述了热输入、合金元素、冷却速率和应变速率对高强钢焊接接头显微组织的影响和高温共聚焦显微镜原位观察高强钢显微组织的最新研究进展,总结了高强钢焊接接头粗晶热影响区显微组织的转变机理.结果表明:通过延长冷却时间、减少热输入量、控制合金元素的含量和采用预处理提高应变速率等方法,可以调控高强钢焊接接头显微组织中马氏体、粒状贝氏...     

基于正交试验的TC4钛合金激光焊工艺优化研究

目的 探究激光功率、焊接速度、离焦量对TC4钛合金激光焊接接头宏观形貌、微观组织及力学性能的影响。方法 通过正交试验方法,研究激光功率、焊接速度、离焦量对接头拉伸性能的影响,并将这3个工艺参数转换为热输入,进一步研究热输入对接头形貌、组织及力学性能的影响。结果 当热输入低于95 J/mm时,焊接接头上下熔宽比较大,焊缝截面呈“V”形;当热输入高于250 J/mm时,接头组织晶粒粗大,甚至出现气孔、错边等冶金缺陷;当热输入为125 J/mm时,焊缝成形美观,焊接接头上下熔宽比接近1,焊缝截面呈“H”形。焊缝区组织主要由原始α相、β相及冷却阶段生成的αʹ相组成,随着热输入的增大,β相柱状晶尺寸逐渐粗化,αʹ针状马氏体相尺寸也相应增大。此外,焊接速度和离焦量对拉伸性能有显著影响,拉伸性能随着热输入的增大呈现先升高后降低的趋势,断口呈韧性断裂特征。当热输入为125 J/mm时,拉伸性能达到最佳,断裂位置发生在母材区,抗拉强度为1 010 MPa,断后延伸率为9.82%;焊缝区中心区域显微硬度高于热影响区及母材区显微硬度。结论 当热输入为125 J/mm时,在TC4钛合金激光焊下,可获得成形美观、性能优良的焊接接头。     

钽条闪光对焊工艺参数对其组织性能的影响

为解决连续化生产中钽条焊接的技术难题,在惰性气体的保护下采用电容储能式预热闪光对焊,对轧制后的4 mm×4 mm钽条进行焊接试验研究.利用金相显微镜、扫描电镜和力学性能检测设备等分析检测手段,对不同焊接顶锻力作用下的焊接区(包括热影响区)的显微组织、晶粒和晶界微区成分、硬度以及焊接区拉伸强度等进行了测试.研究表明,采用合适的闪光对焊工艺可以实现大尺寸钽条的对接,焊缝组织致密,接头具有较高的结合强度,对于大尺寸钽条无头轧制与连续拉拔技术的发展具有一定的使用价值.     

HAZ microstructure simulation in welding of a ultra fine grain steel

In the present work the evolution of grain structure in the weld HAZ (heat affected zone) under welding thermal cycle was simulated. Especially the grain growth in the HAZ of a SS400 ultra fine grain steel was investigated. An integrated 3-D Monte Carlo (MC) simulation system for grain growth of the weld HAZ was developed based on Microsoft Windows. The results indicate that MC simulation is an effective way to investigate the grain growth in weld HAZ. The method not only simulates the non-isothermal dynamics process of the grain growth in the weld HAZ, but also visualizes the austenite grains realistically. Moreover, the thermal pinning effect can be easily included in the simulation process. The grain sizes of the CGHAZ (coarse grain heat affected zone) obtained from MC simulation are basically in agreement with the experimental measurement of the real welded joints under different heat input. Furthermore, the simulation indicates that the grain growth degree is higher for the SS400 ultra fine grain steel compared to conventional steel. With the increase in the heat input, the grain growth of the CGHAZ rapidly increases. Because the activation energy of the grain growth is lower for the SS400 ultra fine grain steel, austenite grains can grow at a relatively lower temperature, hence the range of the CGHAZ becomes wider.     

Effect of heat input on dilution and heat affected zone in submerged arc welding process

Submerged arc welding (SAW) is a fusion joining process, known for its high deposition capabilities. This process is useful in joining thick section components used in various industries. Besides joining, SAW can also be used for surfacing applications. Heat Affected Zone (HAZ) produced within the base metal as a result of tremendous heat of arc is of big concern as it affects the performance of welded/surfaced structure in service due to metallurgical changes in the affected region. This work was carried out to investigate the effect of polarity and other SAW parameters on HAZ size and dilution and to establish their correlations. Influence of heat input on dilution and heat affected zone was then carried out. Four levels of heat input were used to study their effect on % dilution and HAZ area at both the electrode positive and electrode negative polarities. Proper management of heat input in welding is important, because power sources can be used more efficiently if one knows how the same heat input can be applied to get the better results. Empirical models have been developed using statistical technique.     

钛合金薄板激光和钨极氩弧焊残余应力测试研究

采用小孔释放法对钛合金薄板激光焊和钨极氩弧焊(TIG焊)的焊接残余应力进行了测试，并分析了焊接方法、焊接线能量和焊后热处理对残余应力分布规律的影响。研究结果表明：激光焊残余应力分布规律与普通熔焊方法相似，但其分布区域较窄；在热影响区内，激光焊残余拉应力值比TIG焊的约低100MPa；在焊缝及其熔合线附近，激光焊残余应力却比TIG焊的高。对于不同线能量激光焊接，线能量越大，焊缝越宽，热影响区的残余应力也越大。焊后真空热处理能降低残余应力90％。     

Comparison of Laser and Gas Tungsten Arc Weldments of Stabilized 17wt% Cr Ferritic Stainless Steel

One of the major factors influencing weldability of stabilized 17 wt% Cr ferritic stainless steels is extensive grain coarsening in the fusion zone (FZ) and in the heat affected zone (HAZ). This study aimed at exploiting low heat input characteristics of laser welding to effectively control grain coarsening in the FZ and HAZ of 1.2-mm thick stabilized 17 wt% Cr ferritic stainless steel weldment. The study demonstrated that as compared with gas tungsten arc welding (GTAW), laser welding brought about significant grain refinement in the FZ and HAZ. Laser weldments exhibited superior ductility over their GTA counterparts. An important observation of the study was that, in contrast to GTA weldment, laser weldment was associated with weaker interfaces along columnar grain boundaries in the FZ that served to arrest crack propagation normal to them.     

10CrNi3MoV(L)低合金高强钢自动埋弧焊焊接性能研究

采用等强匹配的 1 0MnNi2MoTi合金焊丝和 70 5 ch熔炼焊剂 ,通过改变焊接线能量及道间温度对不同碳含量连铸 1 0CrNi3MoV低合金高强钢板焊接性进行了研究。结果表明 ,连铸 1 0CrNi3MoV钢板具有较好的接头力学性能和焊接工艺适应性 ,但在较大线能量条件下 (～ 4 0kJ cm) ,接头韧性降低。为保证连铸1 0CrNi3MoV钢接头韧性水平 ,在限制自动埋弧焊线能量的同时 ,还应提高钢板韧性 ,控制钢板碳含量     

Microstructure and Fracture Morphology in the Welding Zone of Cr18Mo2 Ferritic Stainless Steel

Microstructure, precipitates and fracture morphology in the weld metal and the heat-affected zone (HAZ) of Cr18Mo2 ferritic stainless steel have been studied by means of metalloscope, SEM,TEM and X-ray diffractometer. Experimental results indicate that crystalline grain coarsening in HAZ is one of the reason resulting in the embrittlement fracture in the welding zone of the ferritic stainless steel. Some precipitates (TiC, TiN and Cr2N) in the steel promote production and development of the brittle cracks. In practical applications. the welding heat input should be as small as possible to prevent embrittlement caused by HAZ grain coarsening.     

大线能量低焊接裂纹敏感性钢的研究

综述了国内大型成套工程用钢中压力容器用钢的研究现状，并指出能极大提高焊接效率，而其热影响区（HAZ）组织均匀细小的大线能量低焊接敏感性的发展趋势及前景。     

The effect of microstructure on hardness and toughness of low carbon welded steel using inert gas welding

The heat affected zone (HAZ), has a great influence on the properties of welded joints since it can alter the microstructure and residual stresses. In this paper, the effect of welding parameters and heat input on the HAZ and grain growth has been investigated. The role of grain size on hardness and toughness of low carbon steel has also been studied.     

锁孔TIG焊接技术的研究进展

锁孔TIG焊接技术具有不开坡口、单面焊双面成形的特点,尤其适用于中厚板焊接。首先介绍了锁孔TIG焊的基本原理,然后分析了目前锁孔TIG焊接波形控制技术的研究现状,主要包括恒流锁孔TIG焊、单脉冲锁孔TIG焊和高低频双脉冲锁孔TIG焊。针对现有锁孔TIG焊接技术存在热输入量过大、接头组织晶粒粗大等缺点,重点介绍了一种新型的快频脉冲TIG焊接技术,它通过快频脉冲电流产生的电磁场对电弧进行压缩,控制焊接过程的热输入量,达到提高焊接质量的目的。与传统脉冲电弧相比,快频脉冲电弧的收缩效果更为明显,可细化焊接接头组织,将快频脉冲焊接技术应用于锁孔TIG焊是今后研究的热点和主要发展方向。     

10CrNi3MoV钢焊接热影响区组织和性能研究

通过热模拟试验研究了１０ＣｒＮｉ３ＭｏＶ 钢在线能量为１５～１００ｋＪ／ｃｍ 范围内时焊接热影响区（ＨＡＺ）组织和性能的变化规律。结果表明,经过一次热循环后,特别是峰值温度为１３００℃时,冲击韧性显著降低。金相分析表明,冲击韧性的降低与组织和晶粒粗大有关,但总体低温冲击韧性能够保持在较高的水平上（Ａ ｋｖ,－ ５０℃＞６０Ｊ）。经过二次热循环后,线能量较低时,热影响区冲击韧性得到改善;线能量较高时,热影响区冲击韧性大大降低