304不锈钢小冲孔蠕变试验与损伤数值模拟研究

对304不锈钢进行了恒定温度下多种载荷的小冲孔蠕变试验,在此基础上建立了304不锈钢小冲孔蠕变试样的有限元模型。应用改进的K-R蠕变损伤本构方程,分析了在650℃、恒载荷条件下的试样中心挠度、应变等随时间的变化规律以及试样蠕变损伤与位置的关系。结果表明,试验与数值模拟结果基本一致,试样中心蠕变曲线都具有明显的三个阶段,与单轴试验的应变曲线十分相似。整个试样在中心损伤比较严重,呈现明显局部化特征。试样的失效首先在下表面,距试样中心约1/10处,这与试验观察到的试样颈缩部位完全一致。

Experimental Study and Numerical Simulation of Creep Damage of Small Punch Creep Test Specimen of SS304 Stainless Steel

The finite element model was established based on the small punch creep test of SS304 steel specimen in the condition of constant temperature and different loads.The variation of central deflection and creep strain with time and the evolution of creep damage subjected to constant forces were analyzed using FEM incorprated with modified K-R creep damage constitutive equations.The test results were in agreement with those of numerical simulation and three different stages appeared in the curve of central creep,which was quite similar with conventional creep tests.The results also showed that the creep damage at the central part was high,and localization of damage was obvious.Initial failure occurred at the bottom surface,0.8mm away from the center which agreed well with the observation from the test.