中文摘要：

X60管线钢是石油、天然气输送用的主要钢种,在外界载荷作用下,易发生局部变形或应力集中,而导致屈曲甚至拉裂失效。对其进行力学研究,评价其力学安全性已成为管道风险管理的重要内容之一。其中,本构关系方程是力学研究的基础内容,失效判据则决定了管道生命的周期。通过对比X60管线钢的静力拉伸实验应力应变关系和Ramberg-Osgood本构关系,发现ε≤εP0.2时,Ramberg-Osgood本构方程能够比较准确地反映X60管线钢的拉伸应力应变关系;但当ε〉εP0.2时,基于Ramberg-Osgood模型所得理论本构曲线与实验结果有较大的误差。基于此,笔者根据X60管线钢静力拉伸弹性阶段和塑性阶段的不同力学特征,采用插值法对Ramberg-Osgood本构模型做出了修正,提出了X60管线钢在单向拉伸状态下的全局二段式应力应变关系式,该关系式更加准确地表达了X60管线钢的拉伸应力应变关系。考虑到焊缝及热影响区对管道强度和刚度的影响,结合塑性材料基于应力的失效判据和基于应变的失效判据,笔者提出了焊缝影响因子及X60管线钢的应变控制失效准则,建立了基于第四强度理论的管道失效时的临界应力计算方程。

英文摘要：

The X60 pipeline steel is the steel which is most commonly applied to the transportation of oil and natural gas,but under the external load,deformation or stress concentration is more likely to occur on the X60 pipeline steel,and thus it results to buckling even cracking failure.For studying the mechanical behavior of the X60 pipeline steel,evaluating its mechanical safety has become one of the most important works for the pipeline risk management.Among all the works of risk management,the constitutive relation equation is the basis of the whole mechanics research,and the failure criterion determines the pipeline＇s life cycle.By comparing the static tensile stress-strain relationship and the Ramberg-Osgood constitutive relation of X60 pipeline steel,we find whenε≤εP0.2,the Ramberg-Osgood constitutive equation can moreaccurately reflect the X60 pipeline steel＇s tensile stress-strain relationship;however,whenεεP0.2,the theoretical constitutive curve,which is based on the experimental results of Ramberg-Osgood constitutive model,has larger deviation.Based on this observation and according to the different mechanical characteristics during the static tensile elastic stage and plastic stage,we make a revision on the Osgood constitutive model by using the interpolation method and propose the X60 pipeline steel＇s global 2-phase stress strain relation under the condition of unidirectional pull-up,which can represent the X60 pipeline steel＇s tensile stress-strain relationship more accurately.Considering the effects caused by the weld seam and heat-affected zone to the pipeline strength and stiffness,and combined with the failure criterion based on the stress and strain about plastic material,this article proposes the influence factor and the failure criterion of the strain control for the X60 pipeline steel,also establishes critical stress calculation equation based on the fourth strength theory at the time of pipeline failure.