峰值温度对X100管线钢及焊缝组织性能的影响

针对管线钢管先内焊后外焊工艺,采用Gleeble3500热模拟试验机研究了外焊不同峰值温度对X100管线钢及其内焊缝组织与性能的影响。结果表明:当外焊峰值温度为1300℃时,母材和内焊缝的韧性大幅下降,硬度上升,在粗晶区均出现了脆化现象,母材韧性损失42%,焊缝韧性损失84%,成为焊接接头韧性最差的区域。同时,在外焊峰值温度为860℃时,母材和内焊缝的韧性也有明显降低。组织分析表明,粗大的、链状M/A岛是韧性变差的主要原因。     

扩散热处理对TC4/TA1钎焊强度和微观组织的影响

对TC4/TA1异种材料不同扩散热处理参数下的剪切强度和母材组织变化进行了综合分析,结果表明,在钎焊参数不变的情况下,将扩散热处理温度确定为920℃,保温时间控制在1h内,不仅可以保持钎焊缝的较高剪切强度,还可以使母材保持较高的韧性,降低母材发生熔蚀的程度,保证钎焊缝以及母材的综合优良性能.     

TC4钛合金直/斜氩弧焊缝疲劳性能研究

针对TC4钛合金氩弧直、斜焊缝的疲劳性能展开对比研究,对氩弧直、斜焊缝的微观组织和疲劳性能进行了对比测试与分析。结果表明:TC4钛合金氩弧焊焊缝显微组织原始β相不断长大,与母材区相比晶粒更粗大;斜焊缝试件的中值疲劳寿命是直焊缝的1.4倍;直、斜焊缝试件疲劳裂纹均起始于试件内部气孔缺陷处,直焊缝试件裂纹在焊缝区扩展至断裂,扩展区有脆性解理特征,而斜焊缝试样裂纹穿过焊缝进入母材扩展至断裂,扩展区有典型韧性扩展特征;在瞬断区,斜焊缝试件比直焊缝表现出更好的韧性。     

TC4-DT钛合金电子束焊接接头的拉伸性能

用电子束焊接50 mm厚TC4-DT钛合金板,对母材、焊缝金属和焊接接头的拉伸性能进行测试,获得了母材和焊缝金属的基本拉伸性能数据,分析了电子束焊接接头显微组织对拉伸性能的影响.结果表明,电子束焊接使TC4-DT钛合金焊缝金属强度增加,塑性和韧性降低,应变硬化能力增强.焊接接头拉伸试验的断裂位置均在离焊缝边缘较远的母材上,母材为整个接头的薄弱环节.母材和焊缝金属拉伸断口均表现出延性韧窝断裂特征.与母材金属相比,焊缝金属拉伸性能的变化与电子束焊接过程中冷却速度快、在焊缝区形成了粗大β柱状晶及针状马氏体有关.     

S420M钢板焊接时的断口分析及对CTOD值的影响

对50 mm S420M钢板模拟焊接,测量了0℃下母材、焊缝和热影响区的CTOD值,并对试样进行宏观断口和SEM断口分析。结果表明:焊缝断裂韧性比母材和热影响区的好;母材、焊缝、热影响区断裂方式为解理断裂,焊缝区断裂时表现出韧性好的特征;母材、焊缝、热影响区断口特征不同,CTOD值不同。     

T92钢焊接接头的组织与性能研究

通过拉伸试验、硬度试验、冲击试验和断口扫描与组织观察,研究了T92钢焊接接头的组织和性能.结果表明,接头的强度高于母材,焊缝金属的硬度高、韧性低,接头的组织特征决定了冲击试样的断裂形态,粗大的奥氏体柱状晶是导致焊缝韧性显著降低的主要因素.因此,改善焊缝金属的结晶条件,有利于提高焊缝金属的韧性.     

Inconel625等离子弧焊接头组织与接头性能研究

对4 mm镍基高温合金Inconel625薄板进行等离子弧焊实验,对比研究了3种不同焊接热输入下焊接接头各部分的微观组织、接头力学性能、断口形貌以及母材和焊缝的高温腐蚀行为。结果表明Inconel625等离子焊接接头组织是由母材的奥氏体等轴晶、焊缝融合线附近的胞状晶以及焊缝中心的树枝晶组成;在焊缝处有大量的碳化物和少量Laves相析出,使得焊接接头力学性能降低,韧性下降,焊缝成为接头薄弱环节;在焊接热输入为10.175 kJ/cm时接头力学性能最优,抗拉强度为765.3MPa,与母材的785.4MPa相当,延伸率为31.9%,相较于母材的42.8%有所下降,试样断裂方式为发生在焊缝处的韧性断裂;母材和焊缝金属在750℃下24 h熔盐腐蚀后腐蚀产物基本相同,主要为外层颗粒状NiO和Cr₂O₃以及NiCr₂O₄腐蚀层。     

13%Cr不锈钢UOE焊管

马氏体系13％Cr 不锈钢是一种比双相不锈钢生产成本低,在 CO_2-Cl~-环境中具有介于碳素钢和双柑不锈钢之间的耐蚀性材料。但是,由于其焊接性能和焊缝部位的韧性不甚理想,因此尚未用来做管线用钢管。日本钢管公司为了开发具有足够焊接性能和焊缝韧性的13％Cr 不锈钢 UOE 钢管,研究了母材和焊接金属的化学成分对焊接性能和焊缝韧性的影响,得到如下结果:①将母材的含 C 量降低到0.03％,可以防止焊接时产生低温裂纹。     

压水堆核电站主管道预制焊缝性能研究

从宏观力学性能与微观金相角度综合分析了压水堆核电站Z3CN20-09M不锈钢主管道预制焊缝的性能。对焊缝进行了力学性能试验,并与母材对比;依据金属学理论,讨论了焊缝金属的化学元素、铁素体组织、析出相对力学性能与耐腐蚀性等的影响。结果表明:控制焊缝区N、Ni、Mo、Si等元素含量,可优化焊缝整体质量;焊缝的拉伸强度高于母材,冲击韧性低于母材;焊缝金属析出相为σ和M_(23)C_6,析出相弥散分布于基体上,对材料有强化效果,但同时降低了焊缝的塑韧性及耐腐蚀性。     

中厚板7A52铝合金光纤激光焊接接头组织与性能

采用光纤激光对8 mm厚度的7A52铝合金板材进行对接焊接试验，分析焊缝上下组织及性能差异. 采用能谱仪（EDS）分析焊缝不同区域合金元素的烧损情况，并对焊缝和母材分别进行拉伸试验，测量焊缝显微硬度.结果表明，焊缝上部区域的显微组织比下部区域小，焊缝上部Mg，Zn 元素含量低于下部边缘；焊缝上部中心的显微硬度高于下部中心，焊缝上边缘的显微硬度小于下边缘； 焊接接头以韧性断裂为主要特征，抗拉强度为325 MPa，为母材的65.9%. 焊缝抗拉强度的降低与Mg，Zn元素的烧损、焊接应力、气孔缺陷等因素密切相关.     

CO2含量对高强钢MAG焊焊缝金属低温韧性的影响

通过调节保护气体中CO2的含量,研究了保护气体氧化性对高强钢焊缝金属低温韧性的影响规律,同时分析了这种影响规律的作用过程。试验结果表明,随着保护气体中CO2含量增加,粒状贝氏体组织在焊缝金属中含量增加,焊缝金属低温韧性降低;当保护气体中CO2含量较少时,焊缝金属组织以针状铁素体为主,焊缝金属具有较高的韧性水平。     

Effect of Mn,Ni, Mo Contents on Microstructure Transition and Low Temperature Toughness of Weld Metal for K65 Hot Bending PipeEI北大核心CSCD

To increase transport efficiency and to lower the costs of pipeline construction, longitudinally submerged arc welded (LSAW) pipes with larger diameters and thicker walls have been increasingly used by the pipeline industry. For example, in Russia, the LSAW pipeline in the Bovanenkovo-Ukhta project was recently constructed with K65 steel (the highest grade of the Russian natural gas pipeline), which is similar in specifications and yield strength requirement (550 MPa grade) to API X80 but has a stricter low temperature toughness value of 60 J at -40 degrees C (compared to - 20 degrees C for API X80 grade) due to the extreme Arctic environment. Although weld metal with acicular ferrite (AF) has been developed to meet the requirement of low temperature toughness, the main objective of the present work was to clarify the microstructural evolution and the resulting changes in mechanical properties after the bending process. Hot bending pipes are necessary links in the construction of pipeline lying, which make more stringent standards for the strength and low temperature toughness. That puts forward a challenge especially to the weld bead because of the deterioration of toughness during the hot bending process. In this work, submerged arc welding wire with high strength and toughness was developed for K65 hot bending pipes, and the alloying elements of Mn, Ni, Mo were considered to estimate the microstructure evolution and the effect of low temperature toughness for the weld metal. The results showed the low temperature toughness at -40 degrees C reached 90 similar to 185 J and 65 similar to 124 J for weld metal of straight seam pipe and hot bending pipe respectively, which reflect the excellent role of alloying elements of Mn, Ni, Mo. Microstructure characterization revealed that the weld metal, which originally consisted mainly of AF in the as-deposited condition, became predominantly composed of bainitic ferrite (BF) after hot bending. In addition, the large size cementite along the grain boundary was also the reason for the deterioration of toughness. It is found that reaustenisation caused a small austenite grain-sized matrix, which brought about a very high volume fraction of bainite. However, the low temperature toughness for hot bending pipe was improved to 124 J for the weld metal with 0.2% Mo, in which about 67.1% of high angle grain boundary were found. It is clear that the process of reaustenitisation during the bending process plays an important role in successful microstructural design for the steel weld metals.     

X80管线钢埋弧焊匹配焊丝试验

通过分析高强度低合金钢焊缝熔敷金属常见显微组织对其力学性能的影响,确定X80管线钢用埋弧焊丝熔敷金属组织应以大量针状铁素体(AF)和少量粒状贝氏体(GB)的复合组织.从相变动力学原理出发,结合针状铁素体(AF)非自发形核机制和微合金组织韧化理论,选择Mn-Ni-Mo-Ti-B合金系进行X80管线钢匹配焊丝的试制.结果表明,合理选择和控制合金元素,可以获得理想的焊缝熔敷金属组织和强韧性以及低温韧性要求,试制的1号焊丝能够满足X80管线钢的使用要求.     

母材成分对X80管道环焊接头冲击性能的影响

管线铺设过程中采用自保护药芯焊丝半自动焊焊接工艺,研究母材中Nb含量对X80管线钢环焊接头冲击韧性的影响。试验结果表明:母材的化学成分对焊缝金属的成分有影响,母材中较高的Nb含量经焊接热循环后过渡到焊缝金属中,促进了焊缝金属中M/A组元的形成和含量的增加,沿晶界分布的M/A组元降低了焊缝金属的冲击吸收功,影响了焊缝金属的冲击韧性及稳定性。经过优化焊接工艺参数,控制焊态焊缝金属的组织形貌、M/A含量及其分布,可保障X80自保护药芯焊丝焊缝金属的冲击韧性控制在较高且相对稳定的水平,但工艺窗口较窄。     

高铌X80管道不同强度匹配环焊接头性能及应变演化

为探究管道环焊缝断裂失效机理,测试了两种不同强度匹配的高铌X80环焊缝接头的组织和性能,并借助数字图像相关法(digital image correlation,DIC)观测了焊接接头在拉伸载荷下的应变行为.结果表明,低强匹配和高强匹配的高铌X80管道环焊接头均具有较好的冲击韧性,二者的夏比冲击吸收能量平均值相当,热影...     

Weldability and SAW welding wire of X80 pipeline steel

0IntroductionWith the rapid development of oil and gas industry,the pipeline construction is in the ascendant in China.Forconsideration of cost and safety,the strength of pipelinesteel and the working pressure of pipeline have been great-ly increased.In the previous pipeline projects X65steelwas used and now West-to-East Transportation Project forexample is mainly using X70steel,and X80steel hasdrawn great attention and is expected to be employed insome trial pipelines in the future.Steel …     

Role of nickel as an interlayer in dissimilar metal friction welding of maraging steel to low alloy steel

Continuous drive friction welding of dissimilar metals, maraging steel and low alloy steel was carried out. It was observed that the hardness, ductility and impact toughness of maraging steel are low due to the diffusion of elements such as carbon, manganese, silicon and phosphorus from low alloy steel to maraging steel. An attempt was made in this study to improve the properties by friction welding of maraging steel and low alloy steel with nickel as an interlayer. The hardness, tensile strength and impact toughness are observed to be improved, as nickel acted as diffusion barrier. The effect of post-weld heat treatments on microstructure and mechanical properties of dissimilar metal friction welds with and without interlayer was also studied. Maraging steel responded to solutionizing & aging and low alloy steel responded to quenching and tempering. The notch tensile strength and impact toughness in case of dissimilar metal weld with interlayer are observed to be more than that of the dissimilar metal weld without interlayer.     

X80/X100异种钢激光-MIG复合焊接头显微组织和性能

采用激光-MIG复合焊对X80管线钢和X100管线钢进行焊接,研究了激光功率对复合焊接头的焊缝形貌、显微组织、硬度、强度和韧性的影响规律.结果表明,激光功率从2.0 k W增大至3.5 k W时,盖面焊缝熔宽和熔深增加,激光区熔深明显增加;激光区焊缝中AF含量增加、LB含量减少,X100侧粗晶热影响区和细晶热影响区中条状贝氏体含量减少,X80侧粗晶热影响区和细晶热影响区中准多边形铁素体含量增加.复合焊接头硬度分布并不对称,最高硬度出现在X100侧熔合区部位.复合焊接头的抗拉强度基本不随激光功率变化,拉伸试样断裂位置均为X80侧母材.随着激光功率增大,焊接接头最高硬度和韧性均下降.     

B610CF钢焊接接头的组织及性能分析

在手工电弧焊和气体保护焊两种焊接方法下,对新开发的调质型低焊接裂纹敏感性低碳贝氏体钢B610CF焊接接头的微观组织和力学性能进行了试验研究.金相分析表明,焊接接头的母材区、焊缝区和热影响区组织均为铁索体和下贝氏体,在铁素体和贝氏体上还弥散分布着渗碳体,说明焊接接头的强度和韧性都较好.拉伸、冲击和弯曲试验表明,焊接接头的抗裂性能好,具有强度高、塑性好、低温韧性和应变失效性能优良的综合力学性能.     

Effect of copper on mechanical properties of high strength SMAW weld-metal

Mechanical properties of SMA W （shielded metal arc welding） weld metal （ yield strength higher than 900 MPa ） with systemazic additions of copper （ up to 1.48 wt% ） were tested, The microstructure and precipitates in different regions were analyzed by optical microscope and transmission electron microscope, The results indicate that copper improves the low temperature toughness of weld metal when the copper content is low and reaches the peak value 48 J （ at - 50℃ ） with 0. 2 wt% copper additions. When the content is high the copper precipitates as 8-Cu phase in the reheat zone of middle beads. These precipitates improve the strength of the weld metal evidently （ yield strength up to 975 MPa） without obvious effect on the low temperature toughness. The copper within 1.1 wt% content can improve the strength without toughness loss.