船用钢Q345D中温塑性成形本构方程建立及分析

Establishment and Analysis of Constitutive Equation of Q345D Ship Steel during Medium Temperature Plastic Forming

采用SANS-CMT万能材料试验机,在温度为473~973K和变形速率为0.001~0.1s^(-1)范围内对Q345D钢板试样进行拉伸实验,并对应力应变实验数据进行分析。结果表明:温度对Q345D钢中温塑性成形影响较大,而应变速率对成形影响较小。随着温度的升高,材料屈服强度σ_s和抗拉强度σ_b出现直线下降,较低温度下,拉伸应力应变曲线出现明显的屈服平台;塑性变形过程中存在着明显的加工硬化现象,加工硬化指数n随温度的上升而下降;延伸率δ随温度的升高近似线性增长;应变速率敏感系数m随温度的升高线性下降。

With a SANS-CMT universal material testing machine,the tensile test of Q345 Dsteel plate specimen was carried out in the temperature ranging from 473 Kto 973 Kand the strain rate ranging from 0.001 s^-1 to 0.1 s^-1,and the stress-strain test data were analyzed.The results show that the temperature has a greater influence on the medium temperature plastic forming of Q345 Dsteel,but the strain rate has less effect on the forming.The material yield strengthσs and tensile strengthσbdecrease linearly with the increase of temperature,and the obvious yield platform appears in the tensile stress-strain curve at lower temperature.The hardening phenomena of Q345 Dsteel are obvious in the process of plastic deformation,and the hardening exponent n decreases with the increase of temperature.With the temperature increasing,the elongation rate δ increases linearly but the strain rate sensitivity coefficient m decreases linearly.