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为研究超高温热处理技术对我国常用Q345B热轧钢材强度的影响规律,以及在减震设计中的应用,完成7个不同参数的超高温热处理及缓慢冷却后的钢材单向拉伸材性试验,研究了热处理极限温度以及冷却速率对于钢材强度及延性的影响。通过3个热处理前后钢材的循环荷载材性试验,得到钢材在循环荷载作用下强度和塑性发展规律,并拟合得到可应用于有限元分析的Chaboche循环本构模型。通过有限元分析了两种局部低强防屈曲支撑,以探讨该种超高温热处理技术在减震设计中的适用性。结果表明:Q345钢材在热处理后强度降低,其强度削弱程度随着热处理极限温度的升高和降温速率的减缓而增加;热处理后的钢材在循环荷载作用下屈服点及屈服平台消失,循环强化现象明显;所设计的2种局部低强防屈曲支撑在循环荷载作用下塑性发展主要发生在热处理段,且具有良好的耗能能力。
In order to study the influence of ultra-high temperature heat treatment on the strength of Q345B hot-rolled steel commonly used in our country and its application in shock absorption design, seven different parameters of ultra-high temperature heat treatment and slow-cooling steel uniaxial tensile test were completed, The effects of heat treatment temperature and cooling rate on the strength and ductility of steel were studied. Through the cyclic loading test of the steel before and after three heat treatments, the law of strength and plasticity of the steel under cyclic loading was obtained, and the Chaboche cycle constitutive model that can be applied to the finite element analysis was fitted. Two local low strength buckling braces were analyzed by finite element method to explore the applicability of this kind of ultra-high temperature heat treatment technology in shock absorption design. The results show that the strength of Q345 steel decreases after heat treatment, and the strength of Q345 steel increases with the increase of ultimate temperature and the decrease of cooling rate. After heat treatment, the yield point and yielding platform disappear under cyclic loading. Obviously, the plasticity of the two kinds of local low-strength buckling braces under cyclic loading mainly occurs in the heat treatment section, and has good energy dissipation capacity.