低铬管线钢5Cr的熔化焊焊接性研究

发布时间：2018-03-05 06:18

  本文选题：5Cr管线钢　切入点：焊接性　出处：《华侨大学》2016年硕士论文　论文类型：学位论文

【摘要】：目前石油管道的运输、储藏主要采用耐蚀合金类钢种,但是此类钢种的大量应用会提高油田的开发成本。研究出一种新材料,并开发出新的制造方法和工艺成了业内关注的焦点,目前有人提出低铬新钢种的利用和开发是一个重要途径,本文针对5Cr管线钢这一新钢种,采用试验和数值模拟的方法,进行焊接性研究,并分析其使用性能。对5Cr钢焊接过程的温度场进行有限元数值模拟分析,研究了温度场分布及热循环曲线。通过研究其焊接条件下连续冷却组织转变,预测其焊接热影响区的组织、性能和硬度。结果表明:5Cr钢在较宽的冷速范围内能够获得含有铁素体的组织类型,具有较高的强度和良好的力学性能。分析所选焊丝与母材的匹配性,分别对三种接头进行成型性分析和抗裂性分析。结果表明:硬面堆焊药芯焊丝YC-YD450焊缝成型性良好,表面光亮,不锈钢焊丝ER308焊缝平整光亮,有轻微变形。低碳钢焊丝H08Mn2SiA焊接平板变形不大。抗裂性试验结果表明,在预热60℃和100℃的情况下,三种焊丝对应的焊接接头均没有发现裂纹。对这三种焊接接头分别进行力学性能测试以及微观组织观察发现:三种焊丝焊接接头熔合良好,未出现缺陷。药芯焊丝焊缝区组织以粒状贝氏体为主,其接头平均抗拉强度为533.52Mpa,普通焊丝焊缝区主要为少量马氏体和羽毛状贝氏体,接头平均抗拉强度为580.16Mpa,不锈钢焊丝焊缝区主要为铁素体和贝氏体,接头平均抗拉强度为547.75Mpa。三种接头断口形貌均表现韧窝,塑性和韧性良好。普通焊丝接头能承受的平均载荷达到17kN,不锈钢焊丝接头平均载荷达到12kN,药芯焊丝接头平均载荷为8kN,弯曲角度大且均未发生断裂,说明三种接头抗弯性能均良好。三种接头冲击试验结果表明,冲击韧性均接近于母材。三种接头的硬度分布规律一致,焊缝中心区较热影响区大,整体母材最低。腐蚀试验发现药芯焊丝平均腐蚀速率为0.0397mm/a,普通焊丝平均腐蚀速率为0.07675mm/a,不锈钢焊丝的平均腐蚀速率为0.0496mm/a,腐蚀形貌也可以看出:药芯焊丝和不锈钢焊丝由于焊缝区Cr元素高于母材而腐蚀不明显,普通焊丝焊缝区腐蚀严重。整体密闭性研究和耐压试验表明:在试验压力3.2MPa、5MPa、10MPa下保持10min,结果发现压力损失率均小于10%,焊缝未见渗水现象,表明圆筒焊缝致密,密闭性良好。三种接头的X射线衍射探伤结果显示,普通焊丝和药芯焊丝接头均未出现夹杂、气孔、裂纹等缺陷。本文研究成果将为5Cr新钢种的结构化应用提供理论依据,节约石油工业的生产开发成本,为实际生产提供了重大的指导。
[Abstract]:At present, the transportation and storage of oil pipelines are mainly made of corrosion-resistant alloy steel, but the extensive application of this kind of steel will increase the development cost of oil fields. The development of new manufacturing methods and processes has become the focus of attention in the industry. At present, it has been proposed that the utilization and development of new low chromium steel is an important way. In this paper, the method of test and numerical simulation is adopted for 5Cr pipeline steel, which is a new kind of steel. The weldability of 5Cr steel was studied and its performance was analyzed. The temperature field distribution and thermal cycle curve of 5Cr steel during welding process were studied by finite element numerical simulation, and the continuous cooling microstructure transformation under welding condition was studied. The microstructure, properties and hardness of the HAZ were predicted. The results showed that the microstructure containing ferrite could be obtained in a wide range of cooling rates. It has high strength and good mechanical properties. The matching between the wire and the base metal is analyzed. The forming property and crack resistance of the three kinds of joints are analyzed respectively. The results show that the YC-YD450 welding seam of hard surfacing flux-cored wire is good. The surface is bright, the ER308 weld of stainless steel wire is smooth and bright, and the welding plate of low carbon steel welding wire H08Mn2SiA is not much deformed. The results of crack resistance test show that, under the condition of preheating at 60 鈩，

本文编号：1569083