摘要
高通量天然气管道在使用过程中由于增压将引发局部变形,对管道材料的服役安全性会产生不利的影响。目前对于预变形引发硬化现象的研究主要集中在母材区域或焊缝区域,而对于含焊缝区域管线钢的研究则甚少。为此,以含焊缝区域的X80管线钢为研究对象,采用不同拉伸预变形量来模拟管道增压形成的单向拉应力,以此为基础研究焊缝和母材协同应变引起的加工硬化对管线钢拉伸性能的影响规律。研究结果表明:①在拉应力的作用下,焊缝区域和母材区域均发生应变响应;②焊缝区域较大晶粒尺寸可以有效增加晶界与内部位错的流动阻力,具有较高的应变硬化能力,使得再次变形时焊缝区屈服强度高于母材区,因此拉伸过程主要集中在母材区域;③预变形量越大,应变硬化现象越显著;④焊缝区的强应变响应能力导致断裂发生在母材区域并且断口形貌由微孔聚集型向准解理型断裂转变。结论认为,该研究成果可以为X80管线钢焊接工艺设计及高通量条件下的天然气管道安全评价提供理论基础和实验依据。
Under the effect of pressurization, a high-flux natural gas pipeline can be locally deformed in the process of its application, and consequently the service safety of line pipe steel will be impacted severely. At present, the studies on the pre-deformation induced hardening phenomenon mainly focus on the base zones or weld zones, but the line pipe steel with weld zones is rarely researched. In this paper, X80 line pipe steel with weld zones was taken as the research object. Different tensile pre-deformation values were adopted to simulate the unidirectional tensile stress generated by pipeline pressurization. On this basis, the effect of work hardening induced by the collaborative strain of weld line and base material on the tensile properties of pipeline steel was studied. And the following research results were obtained. First, under the action of tensile stress, strain response occurs in weld zones and base zones. Second, larger crystalline grains in weld zones can effectively increase the flow resistance of crystalline boundary and internal dislocation, resulting in higher strain hardening capacity. And thus the yield strength of the weld zones is higher than that of the base zones when deformation occurs again, so the tensile process is mainly concentrated in the base zones. Third, the greater the pre-deformation is, the more significant the strain hardening phenomenon is. Fourth, due to the strong strain response in the weld zone, the fracture occurs in the base zone and the fracture morphology changes from the micro-pore aggregation to the quasi-cleavage fracture. In conclusion, the research results can provide a theoretical foundation and an experimental basis for the welding process design of X80 pipeline steel and the safety evaluation of high-flux natural gas pipelines.
作者
武刚
罗金恒
许光达
朱丽霞
李丽锋
陈翠翠
Wu Gang;Luo Jinheng;Xu Guangda;Zhu Lixia;Li Lifeng;Chen Cuicui(State Key Laboratory of Performance and Structural Safety for Petroleum Tubular Goods and Equipment Materials,Xi'an,Shaanxi 710077,China;CNPC Tubular Goods Research Institute,Xi'an,Shaanxi 710077,China;PetroChina West Pipeline Company,Urumqi,Xinjiang 830013,China)
出处
《天然气工业》
EI
CAS
CSCD
北大核心
2019年第7期120-126,共7页
Natural Gas Industry
基金
“十三五”国家重点研发计划项目“原油天然气储罐及附属管道、辅助设施安全评定与风险评价预警研究”(编号:2017YFC0805804)
关键词
天然气管道
X80管线钢
焊缝区域
预应变
应变硬化
拉伸性能
协同变形
断裂行为
韧窝
Natural gas pipeline
X80 line pipe steel
Weld zone
Prestrain
Strain hardening
Tensile property
Collaborative deformation
Fracture behavior
Dimple
