混烃球罐的开裂原因

在停车检验期间某混烃球罐下极带环焊缝处存在大量表面裂纹,采用X射线应力测定仪对裂纹集中部位的残余应力进行测试,并通过化学成分分析、力学性能测试、断口微观形貌观察等方法对球罐开裂的原因进行了分析.结果表明:球罐下极带环焊缝熔合线和热影响区处发生了硫化物应力腐蚀开裂;在腐蚀介质及较大的残余拉应力作用下,裂纹在残余拉应力最大的下极带环焊缝热影响区萌生,随后以穿晶和沿晶形式扩展至熔合线.焊接前应合理选材,选择适合的焊接和热处理工艺,提高球罐安装后去应力热处理的质量,以降低残余拉应力;焊接后通过隔绝腐蚀介质、除去介质中硫化氢或水的方法降低开裂敏感性.     

转化炉原料入口变径管焊缝开裂修复及分析

介绍某制氢装置转化炉原料入口变径管小头侧焊缝开裂修复情况,对开裂焊缝进行失效分析,裂纹起源于管道焊缝内壁,沿晶扩展,在焊缝裂纹断口有碳化铌相析出,导致焊缝晶界脆化,在应力作用下焊缝发生开裂,针对这一问题提出应对策略及解决办法。     

某含硫气田集气站汇管失效原因分析

对开裂的天然气集气末站汇管进行了宏观形貌、显微组织、化学成分分析和力学性能测试、断口形貌观察以及腐蚀产物相组成确定,对其开裂原因进行了分析。结果表明：集气末站汇管开裂裂纹位于汇管的焊缝区,裂纹分为表面裂纹与隐藏裂纹,裂纹性质属氢致开裂和应力导向氢致开裂;设备内壁防腐涂层质量低劣是导致开裂的主要原因,焊接工艺不当对开裂有明显的促进作用。     

锅炉过渡段水冷壁15CrMoG钢连接管安装阶段环向开裂的原因

通过宏观形貌检查、化学成分分析、力学性能测试、显微组织观察和断口形貌分析等方法,探讨了某电厂2号锅炉过渡段水冷壁15CrMoG钢连接管在安装阶段发生环向开裂的原因。结果表明:对口焊接后,鳍片尾部角焊缝未焊透处存在很大的应力集中,同时该处出现了马氏体+贝氏体的淬硬组织,显微硬度非常高,在管系拘束应力、焊接残余应力的作用下,裂纹在此萌生;该部位母材的硬度大、塑性差,在横向拉应力作用下裂纹沿管子环向扩展,从而导致管子发生环向脆性开裂。     

汽车扭力梁加强板焊缝裂纹原因分析

汽车后扭力梁在四立柱耐久试验进行到规定里程近90%时,发现两处加强板和扭梁焊缝末端有明显裂纹。为找出裂纹产生原因,对两裂纹处进行了断口分析、化学成分分析和显微组织分析,并对该结构进行了仿真模拟受力分析。测试结果表明:一处裂纹起源于加强板和焊缝的未焊合处,另一处起源于加强板和焊缝的热影响区,焊缝裂纹的扩展属低应力疲劳扩展。扭力梁和加强板及焊缝的成分、显微组织、焊缝力学性能分析均满足设计要求;仿真分析表明,焊缝末端集中受力远低于屈服强度,存在未焊合缺陷并且服役应力小的区域先于其他服役受力大的区域先开裂。焊缝裂纹的根本原因是存在未焊合焊接缺陷,及焊接过程中的残余应力作用。     

2205双相不锈钢焊接接头裂纹失效机理分析

根据金相分析和断口扫描电镜分析，对2205双相不锈钢焊接接头裂纹进行了分析。结果显示热影响区上裂纹为应力腐蚀开裂。由于焊接的热作用导致焊缝热影响区沿铁素体晶界析出的二次奥氏体和铁素体／奥氏体比例失调，从而造成应力腐蚀开裂。     

SA543钢在高温锅炉水中的应力腐蚀性能试验研究

针对某公司乙二醇装置R-110/R-120环氧乙烷反应器在含磷酸钠锅炉水中出现的应力腐蚀裂纹问题,通过楔形张开加载(WOL)预裂纹试样应力腐蚀试验和慢应变速率试验,研究SA543钢在含Na3PO4锅炉水和改进后含(NH4)3PO4锅炉水中的应力腐蚀开裂行为。楔形张开加载预裂纹试样应力腐蚀试验结果表明,SA543钢在100℃的锅炉水中应力腐蚀裂纹扩展速率几乎为零;慢应变速率试验发现SA543钢在260℃下含Na3PO4的锅炉水环境中的应力腐蚀敏感性指数较大,有应力腐蚀倾向;而在含(NH4)3PO4锅炉水中的应力腐蚀敏感性指数均小于25%,没有应力腐蚀倾向。说明在改进后的高温锅炉水中,SA543钢应力腐蚀裂纹萌生和扩展的抗力明显增强,为环氧乙烷反应器缺陷的安全评定提供了数据支撑。     

不锈钢焊接波纹管失效原因分析

针对某公司不锈钢波纹管膨胀节开裂失效进行了化学成分分析、硬度测试,并进行了裂纹部位金相组织分析、断口解理和断口异物的能谱分析。研究表明,不锈钢波纹管材质的化学成分符合相关技术要求,但主要合金元素铬、镍含量均处下限;断裂面腐蚀区含有与硫、氯相关的腐蚀物,波纹管内壁峰底区加工后的拉应力和服股中拉应力迭加作用下产生应力腐蚀开裂。     

EO/EG装置不锈钢T型三通热疲劳开裂失效分析

某化工企业一不锈钢管道的T型三通环焊缝内壁产生开裂,部分裂纹穿透管壁导致泄漏。通过试验分析表明,管道内143℃高温水注入常温EG水溶液会形成掺混区,对三通下游管壁产生交变的热应力;管道环焊缝在焊缝残余应力和交变热应力作用下产生热疲劳开裂;疲劳裂纹在介质压力、热应力共同作用下扩展,最终导致泄漏。进一步分析得出,通过改变焊缝位置、改变支管接入角度或添加布液器等方法可降低此处热疲劳开裂风险。     

核级手动截止阀Ω焊缝凝固缺陷成因研究

采用显微硬度测量、金相和扫描电镜(SEM)观察对不锈钢手动截止阀焊接接头各微区的硬度进行测量;对Ω焊缝、热影响区(HAZ)和母材的显微组织进行观察;对接头的断口形貌进行观测分析。结果表明:接头各区域的硬度分布差异不大,分布较为均匀,而2#试样HAZ的硬度高于1#。Ω焊缝金属柱状晶粗大,晶粒(柱状和胞状晶)的方向性强,晶间存在偏析,焊缝已形成沿晶界开裂。主要原因是:Ω焊缝装配间隙部位在冷却结晶时因液态填充不够,形成缩松、缩孔。在焊接应力/应变场作用下,拉伸应变或应变率超过此时材料的临界塑性和临界应变率时则产生焊接凝固裂纹。     

An investigation on SA 213-Tube to SA 387-Tube plate using friction welding process

Friction welding of tube to tube plate using an external tool (FWTPET) is a relatively newer solid state welding process used for joining tube to tube plate of either similar or dissimilar materials with enhanced mechanical and metallurgical properties. In the present study, FWTPET has been used to weld SA 213 (Grade T12) tube with SA 387 (Grade 22) tube plate. The welded samples are found to have satisfactory joint strength and the Energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD) study showed that inter metallic compound is absent in the weld zone. The different weld joints have been identified and the phase composition is found using EDX and XRD. Microstructures have been analyzed using optical and Scanning electron microscopy (SEM). The mechanical properties such as hardness, compressive shear strength and peel test for different weld conditions are studied and the hardness survey revealed that there is increase in hardness at the weld interface due to grain refinement. The corrosion behavior for different weld conditions have been analyzed and the weld zone is found to have better corrosion resistance due to the influence of the grain refinement after FWTPET welding process. Hence, the present investigation is carried out to study the behavior of friction welded dissimilar joints of SA 213 tube and SA 387 tube plate joints and the results are presented. The present study confirms that a high quality tube to tube plate joint can be achieved using FWTPET process at 1120 rpm.     

改善SA387Gr11CL1（H）钢焊缝低温韧性的试验研究

某台SA387Gr11CL1（H）钢冷换设备的产品焊接试板在进行力学性能试验时,焊缝一18℃冲击功不合格。通过分析研究和焊接工艺试验,查明了导致焊缝韧性不合格的原因。经过多次热处理试验,确立了适合的热处理工艺,运用于该台设备壳体焊缝中,显著提高了原焊缝的韧性,取得了良好效果。     

Research on corrosion behavior of A6N01S-T5 aluminum alloy welded joint for high-speed trains

For high speed trains, safety is of utmost importance. Salt fog corrosion, intergranular corrosion tests were employed to observe the corrosion behavior of welded joint of A6N01S-T5 aluminum alloy of high-speed trains. Tensile strength and hardness changed after corrosion was tested. The micro morphologies were observed by metalloscope and laser confocal scanning microscope (LCSM). The corrosion loss and corrosion loss ratio were also investigated. The results showed that the heat affected zone (HAZ) was the most sensitive to corrosion in welded joint in the salt fog corrosion test. The potential of the corrosion of the intermetallic compound on the surface was different from the Al matrix potential, which easily generated corrosion micro-batteries that generated the corrosion pit. The weld zone was the most sensitive to corrosion in the welded joint in the intergranular corrosion test, because much corrosion produced an intermetallic phase such as CuAl₂, MgZn₂, Mg₅Al₈, which formed the deficient Cu or Mg zone potential. The potential is low, which acted as an anode and corroded. The residual stress test on the weld of the A6N01S-T5 of the W1 of the exterior surface of roof of high speed train showed there was distributed high tensile stress and compressed stress in the weld zone, HAZ zone and matrix zone. The defects will spread under the high stress and make the corrosion become severe.     

锥形光头搅拌针搅拌摩擦焊接铝锂合金接头组织及力学性能

采用锥形光头搅拌针搅拌摩擦焊接5mm厚铝锂合金轧制板材，并对接头微观组织、力学性能及断裂特性进行了深入研究。结果表明，接头由焊核区、热机影响区和热影响区构成。焊核区在焊接过程中发生动态再结晶，形成细小的等轴晶晶粒，晶界处分布有大量的偏析相，热影响区组织发生粗化，形成粗大的板条状组织，前进侧热机影响区组织发生回复反应，后退侧热机影响区发生回复 再结晶反应；硬度测试结果表明，接头发生软化，后退侧材料的软化区间和软化程度均高于前进侧；断口实验结果表明，接头断裂模式为解理断裂。     

西气东输二线工程X80钢管半自动焊工艺研究

以西气东输二线工程用X80钢管为研究对象,通过焊接接头横向拉伸试验,焊缝和热影响区（HAZ）冲击韧性试验,焊缝和HAZ不同焊层显微组织分析,以及焊接接头不同焊层Hv10硬度试验等手段,研究了低氢型焊条根焊和自保护药芯焊丝半自动填充、盖面组合焊接工艺的环焊缝的焊接接头性能。试验结果表明,选择韧脆转变温度较低的自保护药芯焊丝、采用较小的焊接热输入量和多层多道的焊接措施等因素,对于保证X80钢管环焊接头的性能是至关重要的。采用低氢焊条根焊、自保护药芯焊丝半自动焊进行X80钢管焊接时,焊接接头的强度、-10℃低温冲击韧性和硬度等性能良好．该工萝应用于西气东输二线工程的焊接旆工是可行的．     

SA336F22CL3钢制高压换热器的制造

重点介绍SA336F22CL3钢制高压换热器制造过程中的材料技术指标、复验、焊接工艺过程控制及检验。通过选取适当的焊接、热处理及组装工艺，制成的高压换热器较好地保证了产品质量，各项力学性能指标包括焊接接头的抗回火脆性性能均达到设计要求，为同类钢材关键设备的国产化提供了借鉴。     

SS400钢焊接接头抗断性能的数值评估

SS400钢是一种超细晶粒、超纯净、具有优良综合力学性能的新一代钢铁材料，其焊接结构性能的研究对其推广应用具有重要的意义。文中通过数值分析方法，以SS400母材性能为参照，对其实际焊接接头的抗断裂性能进行评估。采用MARC商用软件，对不同中心贯穿裂纹尺寸的SS400母材及其实际焊接接头拉伸板模型进行三维有限元计算和拉伸过程模拟。焊接方法为脉冲熔化极混合气体保护焊，焊接板的中心裂纹处于焊缝与热影响区之间的熔合区。用作比较的母材板的裂纹尺寸和位置、网格划分、边界条件等与焊接板完全相同。根据计算结果，分析焊接接头力学不均匀性对应力应变场的影响，并依据全面屈服理论对断裂参量CTOD进行分析比较。结果表明，焊接接头的CTOD值均低于同裂纹尺寸的纯母材。因此，该焊接接头拉伸板的抗断性能应优于纯母材。     

不同类型接管安全端焊接接头常温断裂韧性对比研究

对带镍基合金隔离层和无隔离层两种不同类型接管安全端焊接接头的常温断裂韧性进行对比研究,研究结果表明:接头焊缝区的J-R阻力曲线和断裂韧性高于SA508区域,低于316L区域。界面裂纹的J-R阻力曲线和断裂韧性最低,界面区域的延性裂纹起裂和扩展阻力最小。带隔离层接头中熔合区、热影响区和焊缝中心区的J-R阻力曲线和断裂韧性J 1c略高于无隔离层接头的对应区域。无隔离层接管安全端接头的J-R阻力曲线和断裂韧性可以达到带隔离层接头的水平。     

Effect of welding heat input on fatigue life of quenched boron steel and FB steel lap joint

The effect of welding heat input on the fatigue life of a quenched boron steel and ferrite-bainite (FB) steel lap joint was investigated. Boron steel was quenched and welded with FB steel in heat input ranging from 0.29 to 0.67 kJ/mm. Boron, which can increase hardenability, affected the microstructure and hardness of the weld metal and heat affected zone (HAZ). The hardness of the weld metal and HAZ increased with decreasing welding heat input, and the high hardness of the weld metal and boron steel HAZ prevented the initiation of cracks in the stress concentration area around the bead. The bead width increased with increasing heat input, and the results of finite element method (FEM) showed that the maximum stress in the notch of the weld joint decreased when the bead width was increased. That is to say, the fatigue life increased when the weld joint had wider bead width. Finally, while the fatigue life was affected by the residual stress, the variation of the welding heat input used in this study had hardly any affect on the residual stress distribution.     

SA387Cr11.CL2钢拼焊大型封头热处理工艺试验

通过对SA387Cr11.CL2钢大型封头焊接试板的热处理工艺,进行多次试验,找出了合适的热处理工艺;并通过合理的工装,有效控制了封头的变形。