STRAIN HARDENING EXPONENT MODEL AND ITS INFLUENCE ON FAILURE PRESSURE OF STEEL PIPELINE

Based on the strain hardening effect of steel materials and deformation instability theory, the numerical solution of strain hardening exponent is obtained and its influence on the ultimate internal pressure bearing capacity of pipes is clarified.According to the actual burst pressure data of intact pipeline, the applicable range of strain hardening index is developed.The results show that: the strain hardening exponent can be obtained by solving the yield ratio and yield strain, and the numerical solution is slightly smaller than the true value. The hardening performance of pipelines enhances with the increase of strain hardening exponent n and hardening coefficient K. The higher the strength grade of steel, the smaller the hardening exponent n and the lower the failure stress. The failure strain of the pipeline is equal to half of the true strain corresponding to the tensile strength. Whether or not to consider the strain hardening of steel materials, the difference between failure pressure errors is 2.24%~6.08%, in which von Mises yield is more sensitive to the computational model of strain hardening index.