摘要S30408奥氏体不锈钢因其优异的力学性能和耐低温性能而被广泛用于制作LNG等低温罐车罐体的内容器。此类罐体的内容器在其支撑部位不但承受内压引起的恒定应力还会承受惯性载荷引起的交变应力，容易发生渐进的塑性应变累积即棘轮效应。但目前还缺乏有效预测S30408低温棘轮效应的本构描述。利用几种较为先进的本构模型对低温S30408奥氏体不锈钢棘轮应变进行模拟，发现这些本构模型存在循环初期过低预测和循环后期过高预测的缺点，并且这种过高预测会随着循环圈数的增加而增大。基于Ohno - Wang II模型，关联形变马氏体含量与各向同性强化与随动强化，并给出马氏体极限含量dL的演化规律，进而提出一种含马氏体相变的循环塑性本构模型。与其它模型相比，该模型能有效改善在循环初期预测值过低和后期预测值过高的情况，同时能够较好地预测循环加载过程中形变马氏体的含量。
Abstract：S30408 austenitic stainless steel is widely used to make the inner container of LNG and other cryogenic tanker due to its excellent mechanical properties and low temperature resistance. The inner container of this type of tank can not only bear constant stress caused by internal pressure, but also bear alternating stress caused by inertial load at its supporting part, which is prone to gradual plastic strain accumulation, i.e. ratcheting.However, there is still a lack of constitutive description to effectively predict the low temperature ratcheting effect of S30408. The ratcheting strain of low temperature S30408 austenitic stainless steel is simulated by sevseral more advanced constitutive models. It is found that this several constitutive models have the the disadvantages of low-prediction in the early cycles and over-prediction in the late cycles. And this difference will increase with the number of cycles. Based on the Ohno-Wang II model, this paper associates deformation martensite content with isotropic and kinematic hardening rule, and gives the evolution rule of martensite limit content dL, and then proposes a cyclic plastic constitutive model containing martensite transformation. The dL of the martensite limit content in this paper can better describe the variation rule of martensite limit value with the accumulated plastic strain. Through the simulation of low temperature S30408 austenitic stainless steel by sevseral more advanced constitutive models and the new constitutive model, it is found that the model can effectively improve the situation that the predicted value is too low in the initial cycles, and can also well describe the situation that the material reaches ratchet stability in the later cycles.
2020, Vol. 41 
