排序方式: 共有38条查询结果,搜索用时 15 毫秒
1.
Hydrogen diffusion coefficients of different regions in the welded joint of X80 pipeline steel were measured using the electro-chemical permeation technique. Using ABAQUS software, hydrogen diffusion in X80 pipeline steel welded joint was studied in consideration of the inhomogeneity of the welding zone, and temperature-dependent thermo-physical and mechanical properties of the metals. A three dimensional finite element model was developed and a coupled thermo-mechanical-diffusion analysis was performed. Hydrogen concentration distribution across the welded joint was obtained. It is found that the postweld residual hydrogen exhibits a non-uniform distribution across the welded joint. A maximum equivalent stress occurs in the immediate vicinity of the weld metal. The heat affected zone has the highest hydrogen concentration level, followed by the weld zone and the base metal.Simulation results are well consistent with theoretical analysis. 相似文献
2.
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. 相似文献
3.
采用美国BROCO水下焊条对16mm厚的Q345钢板分别进行陆上和水下湿法焊接试验,分析陆上和水下焊接接头的显微组织和接头硬度分布,计算焊接过程的温度场分布和残余应力场分布,并研究焊接电流对温度场和残余应力场的影响。结果表明,相同的电流条件下,水下焊接接头的显微组织类型和构成与陆上焊接接头不同,焊缝可以获得更细的侧板条铁素体组织和针状铁素体,粗晶区组织主要为高硬度的马氏体;增加水下焊接电流,焊缝中侧板条铁素体增加。计算结果表明,170 A电流的水下焊接相比陆上焊接可获得较低的焊接温度、更快的焊后冷却速度和更高的等效残余应力峰值水平;水下焊接电流增加到190A时,焊接最高温度有所升高,焊后冷却速度略有降低,等效残余应力峰值水平下降。 相似文献
4.
5.
6.
7.
8.
采用热模拟技术研究了热输入和层间温度对9%Ni钢焊接热影响区中四个亚区域低温韧性的影响,并利用光学显微镜、X射线衍射仪对各亚区域的组织形态和数量分布进行了观察分析。结果表明,临界热影响区低温韧性对热输入和层问温度的变化不敏感;层间温度是影响粗晶区低温韧性的主要工艺参数;热输入则是影响过临界粗晶区和临界粗晶区低温韧性的主要工艺参数。热输入越大,晶粒和组织越粗大,低温韧性恶化;层间温度提高,马氏体的自回火作用越显著,低温韧性改善。因此,焊接9%Ni钢时,应采用较小的焊接热输入,配合较高的层间温度。 相似文献
9.
回顾总结了液化天然气低温储罐用9%Ni钢的研究和发展,对9%Ni钢的显微组织结构、力学性能以及现场焊接性进行了介绍.使用最普遍的淬火 回火态9%Ni钢的组织形态主要为回火马氏体,并分布有少量残余奥氏体.9%Ni钢具有很高的强度和良好的低温韧性,焊接性良好,冷裂敏感性较低,采用合适的焊接工艺措施,可防止热裂纹的出现,获得具有良好低温韧性的焊接接头.9%Ni钢焊接时,焊接热输入一般控制在7~35 kJ/cm,多层焊层间温度应控制在100℃以下. 相似文献
10.
The y-groove Tekken test has been performed to evaluate the cold cracking susceptibility of X100 pipeline steel. The impact of preheating state on the microstructure, distribution of hardness, and the stress-strain state in the welded joint was analyzed. The results show that X100 pipeline steel reveals a low susceptibility to cold cracking with cracking ratios below 20%. It is found that elevated preheating temperature leads to longer cooling time in the welded specimen and ultimately results in a lower cold cracking susceptibility. Preheating temperatures of up to 100 ℃ are favorable in decreasing the cold cracking susceptibility due to a relative fine microstructure and low M-A constituent amount in coarse grained heat affected zone, a low hardenability, and low-level residual stress and strain. However, excessive preheating temperatures of 150 ℃ and 200 ℃ lead to grain coarsening, higher M-A constituent amount, higher residual stress level and increasing strain level in the Tekken specimens. Preheating temperature above 150 ℃ is not favorable for decreasing the cold cracking susceptibility of X100 steel. 相似文献