激光焊接650MPa相变诱发塑性钢的组织与性能

采用固体Nd:YAG激光器焊接拉伸强度级别为650MPa、厚度为1.2mm的相变诱发塑性钢(TRIP)薄板,利用光学显微镜和电子显微镜研究了其不同焊接速度下对接焊缝的形貌和组织特点。测试了接头的硬度和抗拉强度,借助杯凸试验对比研究了激光焊接接头和母材的成形能力,并分析了焊接速度对接头组织、性能的影响。研究表明:TRIP钢的相组成主要是大量铁素体、贝氏体和少量的残余奥氏体;激光焊缝金属则主要由马氏体构成。焊缝金属或焊接热影响区的近缝区具有最高的硬度。焊缝金属的屈服强度和抗拉强度在垂直于焊缝方向与母材基本相同,但在平行于焊缝方向明显高于母材。与母材相比,激光焊接TRIP钢薄板的冲压成型能力明显下降。     

X80钢焊接接头在酸性模拟液中的电化学腐蚀

采用电化学测试、金相显微镜观察,研究了X80管线钢及其焊缝组织在酸性模拟液中的电化学腐蚀行为.结果表明:X80管线钢母材的显微组织主要为针状铁素体,整体上看母材的组织较为均匀、细小,位向大致呈带状分布.焊缝的显微组织由先共析铁素体、针状铁素体和珠光体组成,焊缝的晶粒大小不均匀,整体上比母材组织粗大.在酸性模拟液中,X8...     

3-sheet structure of Inconel 718 superalloy processed by LBW/SPF and its load response

The 3-sheet structure of Inconel 718 superalloy will be used in flying vehicles as heat resisting and shielding structure due to its lightweight, high strength and stiffness. The 3-sheet structure of Inconel 718 superalloy processed by LBW/SPF (laser beam welding/superplastic forming) technology exhibited good configuration and uniform thickness distribution. The LBW parameters for 3-sheet structure were as follows: Pulse frequency was 32 Hz, impulse duration 3 ms, peak power per pulse 4500 W, and welding speed 180 mm/min. The SPF parameters were as follows: Temperature T=965°C, forming pressure P=4.2 MPa, and forming time t=130 min. The microstructure in weld fusion zone was constituted of austenite dendritics and Laves phase precipitated in interdendritics. After the SPF process, austenite dendritics in the weld fusion became coarser and most of Laves phases were dissolved and turned into δ precipitated phase, but a few of Laves phases were still reserved. And Nb concentration in dendritics increased to 5.42% compared to 2.82% in as-weld condition. Weld metal Vickers-hardness increased from 331.63 in as-weld condition to 391.74 in post-SPF condition which was closed to the base material Vickers-hardness of post-SPF. Grain size of base material grew slightly and an amount of precipitated phase appeared in the base material undergoing SPF process. The tensile test results of base material showed that tensile strength increased obviously and the ductility decreased slightly after SPF process. Load response test results indicated that the 3-sheet structure possessed good resistance to compression and bending load. Accordingly, the LBW/SPF technology is an appropriate forming technique for the 3-sheet structure of Inconel 718 superalloy. Supported by the National Natural Science Foundation of China (Grant No. 50672106) and the Intellectual Innovation Project of the Chinese Academy of Sciences (Grant No. KJCX3-SYW.No.12)     

薄板铝合金的CMT焊接工艺

为了解决利用传统焊接方法焊接铝合金时容易造成生产效率低、焊接变形大以及夹钨、裂纹、气孔等缺陷,对6082-T6铝合金进行了冷金属过渡焊,并确定了最佳焊接工艺参数.利用金相显微镜、扫描电子显微镜、能谱分析仪和X射线衍射仪对铝合金的焊缝成型、显微组织与相组成进行了分析.利用维氏显微硬度计和万能拉伸试验机测量了焊接接头的硬度和拉伸力学性能.结果表明,在最佳焊接工艺参数下6082-T6铝合金焊缝成型良好,其焊缝组织主要由α-Al固溶体组成.焊接接头的拉伸断裂位置处于热影响区,其最高拉伸强度约为母材的61%,拉伸断口形貌为塑性断口.     

镍基合金焊缝金属热裂纹及接头强韧性的研究进展

综述了镍基合金焊缝金属在热裂纹及接头强韧性方面的最新研究进展,得出:1)焊丝中添加Nb、Al、Ti、Ce等合金元素可降低焊缝金属高温失塑裂纹敏感性,添加Mn和Mg可抑制S、P、Si、Bi等低熔点化合物的生成,控制药芯组成中TiO2、SiO2、ZrO2、MnO2等造渣剂之间比例关系,有助于提高焊缝金属抗热裂纹性;2)采用合适的焊接工艺可有效避免焊缝金属热裂纹的产生,其中,激光焊、电子束焊等新型焊接工艺对焊缝金属热裂纹的影响逐渐成为研究热点;3)采用固溶+双级时效的焊后热处理工艺,可改善焊接接头的强韧性,焊丝中添加Al、Ti、Nb、Mo、Mn等合金元素可提高焊接接头抗拉强度,但随着Mn质量分数的增加,接头冲击韧性降低.     

Effect of Direct Quenching and Partitioning Treatment on Mechanical Properties of a Hot Rolled Strip Steel

Three different online heat treatment processes were designed to study the effects on the mechanical properties of a 0.19C-1.6Si-1.6Mn(wt%) hot rolled strip steel.The microstructures were characterized by means of SEM,TEM,EPMA,and XRD.The mechanical properties were estimated by tensile tests.Results showed that a satisfying combination of strength and ductility could be obtained through the ferrite relaxation and direct quenching and partitioning process.Analysis was also focused on this process.The microstructure contained proeutectoid ferrite grains,martensite packets and blocky or interlath retained austenite,and also contained carbide-free bainite in the case of relatively high quench temperatures.The retained austenite fraction was increased through proeutectoid ferrite and partial bainite transformation,while the tensile strength was also consequently decreased.The most of retained austenite transformed to ferrite under deformation and the elongation was obviously improved.     

微量元素Cr对船用耐蚀钢焊接接头组织和性能的影响

为了探讨货油舱下底板模拟腐蚀环境下微量元素Cr对耐蚀钢焊接接头组织、力学性能和腐蚀性能的影响,分别使用不含Cr的焊丝和含微量Cr的焊丝焊接耐蚀钢,对所得焊接接头进行研究.对比分析无Cr及含微量Cr的焊接接头的组织及性能.结果表明,Cr元素的微量添加在一定程度上抑制了先共析铁素体,并且细化了针状铁素体.焊缝中微量Cr的存在对接头的力学性能影响大,无论添加与否接头的抗拉强度均比母材抗拉强度要高,且冲击水平也未发生大的改变,硬度分布相似.焊缝中添加微量Cr元素并未明显改善它的耐腐蚀性,相反,使得焊缝金属自腐蚀电位下降、腐蚀速率增高.     

Effects of laser heat treatment on salt spray corrosion of 1Cr5Mo heat resistant steel welding joints

The surface of 1Cr5 Mo heat-resistant steel welding joint was processed with CO2 laser, and the corrosion behaviors before and after laser heat treatment(LHT) were investigated in the salt spray corrosion environments. The microstructures, phases, residual stresses and retained austenite content of 1Cr5 Mo steel welding joint before and after LHT were analyzed with optical microscope and X-ray diffraction, respectively. The cracking morphologies and chemical compositions of corrosion products after salt spray corrosion were analyzed with field emission scanning electron microscopy(FESEM) and energy disperse spectroscopy(EDS), respectively, the polarization curves were measured on a PS-268 A type electrochemical workstation, and the mechanism of corrosion resistance by LHT was investigated as well. The results show that the passive film of original sample is destroyed owing to the corrosive media penetrating into the subsurface, resulting in the redox reaction. The content of residual austenite in the surface and the self-corrosion potential are increased by LHT, which is contributed to improving the capability of salt spray corrosion resistance.     

新型准贝氏体钢及工程应用

研究了新型准贝氏体钢的组织特征与性能特点 .结果表明 :由贝氏体铁素体和残余奥氏体组织组成的准贝氏体钢是一种热处理工艺优良、焊接性能优异 ,并具有良好的耐磨性、较高的抗疲劳性能、低的缺口敏感性的新型工程结构材料 .并阐述了准贝氏体钢在工程应用中成功的实例及应用前景     

S30408焊接接头低温力学性能试验

为了研究国产奥氏体不锈钢S30408在低温下的力学性能变化规律,通过-196~20℃下的低温拉伸试验和冲击试验,获得S30408焊接接头与母材的低温拉伸性能和冲击性能数据.试验结果表明：焊接接头与母材的屈服强度和抗拉强度随温度降低呈现明显的增加趋势,低温强化效应显著;夏比冲击吸收能量和侧膨胀值则随温度降低呈现下降趋势;焊缝处铁素体含量最高,冲击韧性最差,且焊缝处冲击韧性的降低与其本身在低温下抵抗裂纹扩展能力的降低有关;铁素体分布的不均匀性致使焊接接头存在微观力学性能的差异,对接头处变形产生塑性拘束,削弱了焊接接头的承载能力.     

激光熔凝处理对轧辊钢组织及性能的影响

应用3KW连续CO2激光器对轧辊钢进行激光熔凝处理,用金相用显微镜、、SEM及71型显微硬度计,进行湿微组织分析和显微微硬度测试。结果发现,其剖面组织区域分为熔化区（粗大的马氏体＋残余奥氏体→奥氏体)、相变区（马氏体＋残余奥氏体＋碳化物）、热影响区和基体4个部分,各区域的尺寸及显微硬度与功率、扫描速度等工艺参数有关,且激光处理后硬化效果明显。     

高速客车转向架构架焊接接头组织与力学性能

采用混合气体保护焊焊接方法对进口S355J2W钢和国产09CuPCrNi-A钢两种耐候钢通过焊接机器人单面焊双面成型的方式进行自动焊接实验,通过拉伸、硬度和金相检验试验方法对得到的焊接接头显微组织和力学性能进行了分析研究。结果表明,两种钢材焊接接头抗拉强度均优于母材,具有良好的力学强度,能够满足国产化技术要求。两种钢的焊接接头焊缝组织类似,S355J2W钢焊缝主要为粗大板条状和块状铁素体加先共析铁素体,含少量珠光体和粒状贝氏体;09CuPCrNi-A钢焊缝主要为条状和针状铁素体加先共析铁素体,含少量珠光体和粒状贝氏体。     

微碳钢铁素体区热轧试验研究

在连铸连轧生产线采用铁素体轧制技术制备微碳钢热轧薄板,并对所制备薄板的组织、性能及织构进行分析。结果表明：铁素体轧制微碳钢热轧薄板的组织为完全再结晶铁素体,平均晶粒尺寸50 m左右。相对于常规奥氏体轧制,铁素体轧制薄板的屈服强度和抗拉强度分别下降了21%和6%,延伸率略有下降。热轧薄板的塑性应变比值为0.4,明显低于常规奥氏体轧制。薄板中存在较强的{001}织构是导致值较低的主要原因。     

X80管线钢变形能力的微观结构设计

在原有X80管线钢微观结构的基础上,通过不同的热处理工艺引入等轴状铁素体作为塑性相来提高管线钢的塑性变形能力,分析等轴状铁素体含量对管线钢强度、塑性和冲击韧性的影响。结果表明,随着等轴状铁素体含量的增加,管线钢的抗拉强度、屈服强度和冲击韧性逐渐下降,但均匀伸长率增加。     

电站 F/A 异种钢接头早期失效及其防治措施

扼要归纳了Ｆ／Ａ异种钢接头早期失效的特征,分析了导致早期失效的因素,提出可用焊后高温回火和适当增加铁素体侧坡口角的办法降低钢１０２／Ｉｎｃｏｎｅｌ１８２／ＴＰ３４７Ｈ接头的早期失效倾向．文章列出的高温持久强度试验、高温承载加速模拟试验、残余应力测试等结果以及热应力的有限元分析都证明了上述措施是有效的．     

S690Q高强钢对接节点的焊后性能

通过试验研究了S690Q高强钢对接节点的焊后性能.利用手工电弧焊焊接了3个厚度为8 mm的S690Q高强钢对接节点,焊接过程中对3个节点分别采用不同的焊接热量.在微观层面上,用微观结构测试和微观硬度测试研究焊接对于节点的影响;在宏观层面上,通过拉伸试验研究焊接对于节点力学性能的影响.微观结构测试结果表明,S690Q高强...     

Effect of welding process on the microstructure and properties of dissimilar weld joints between low alloy steel and duplex stainless steel

To obtain high-quality dissimilar weld joints, the processes of metal inert gas (MIG) welding and tungsten inert gas (TIG) welding for duplex stainless steel (DSS) and low alloy steel were compared in this paper. The microstructure and corrosion morphology of dissimilar weld joints were observed by scanning electron microscopy (SEM); the chemical compositions in different zones were detected by en-ergy-dispersive spectroscopy (EDS); the mechanical properties were measured by microhardness test, tensile test, and impact test; the corro-sion behavior was evaluated by polarization curves. Obvious concentration gradients of Ni and Cr exist between the fusion boundary and the type II boundary, where the hardness is much higher. The impact toughness of weld metal by MIG welding is higher than that by TIG weld-ing. The corrosion current density of TIG weld metal is higher than that of MIG weld metal in a 3.5wt% NaCl solution. Galvanic corrosion happens between low alloy steel and weld metal, revealing the weakness of low alloy steel in industrial service. The quality of joints pro-duced by MIG welding is better than that by TIG welding in mechanical performance and corrosion resistance. MIG welding with the filler metal ER2009 is the suitable welding process for dissimilar metals jointing between UNS S31803 duplex stainless steel and low alloy steel in practical application.     

高性能耐候建筑钢的焊接性能研究

对高性能耐候建筑用钢的手弧焊和埋弧焊焊接接头力学性能、组织结构、最高硬度以及电化学腐蚀性能进行研究。试验结果表明，该钢具有优异的焊接性能、较低的焊接冷裂纹敏感性和良好的耐大气腐蚀性能。     

Z3CN20-09M铸造奥氏体不锈钢的形变与断裂机制

为研究Z3CN20-09M铸造奥氏体钢的形变与断裂过程,利用微型拉伸夹具对铸造奥氏体不锈钢在金相显微镜和扫描电镜下进行了动态拉伸和微观形貌原位观察.试验结果表明,在拉伸形变初期奥氏体中先出现滑移线,滑移线与铁素体的分布形态平行或是近乎平行;随着载荷的增大,奥氏体变形加剧且铁素体中开始出现粗而间距大滑移线.在拉伸形变后期,裂纹首先在杂质和奥氏体与铁素体相界处萌生,并向铁素体相扩展.     

激光-电弧复合焊接高强钢的性能

为了研究焊接参数对激光-电弧复合焊接性能的影响,采用了2 k W光纤激光器和MAG(熔化极活性气体保护焊)复合焊接780 MPa高强钢板,通过高速摄像机观察了熔滴过渡形式及激光(或电弧)先导的等离子体形态,研究了激光(或电弧)先导的特性、激光与电弧间距离、离焦量、MAG电流和熔滴过渡形式对激光-电弧复合焊接性能的影响.结果表明,电弧先导的焊缝成形更好;等离子体不仅影响焊缝形状,而且影响激光-电弧间最佳距离;激光与电弧间距对熔宽的影响较小;焊接电流影响焊缝形状和熔深,随着焊接电流的增加,熔深增加,当离焦量为-2 mm时熔深最大.