DH36钢拉伸塑性流动特性及本构关系

Tensile plasticity flow characteristics of DH36 steel and its constitutive relation

对DH36钢在温度从293-800K、应变率为0.001和0.1s-1的拉伸塑性流动特性进行实验研究,通过端口形貌图对变形前后的试样进行了微观分析,结果表明：（1）在实验温度范围内,0.001和0.1s-1的应变率下,第三型应变时效现象出现,随应变率的增加,时效发生的温度区域移向更高温度;（2）第三型应变时效的发生与合金原子在晶界和晶粒中大量的第二相析出强化有关联;（3）建立包含第三型应变时效现象的统一本构模型,通过比较该模型能够较好的预测DH36的塑性拉伸流动应力。

The tensile plasticity flow properties of high-strength structural steel DH36 weresystemati- cally studied at the temperature range from 293 to 800 K and the strain-rate range from 0. 001 to 0.1 s-1 by using a quasi-static testing machine. And the high-strength structural steel DH36 under- went the strain over 25%. Then, the microstructures of the DH36 samples were analyzed by applying the scanning electron microscopy before and after deformation. The experimental results show that the third-type dynamic strain-aging （SA） phenomenon disappears in the test temperature range at the strain rates of 0. 001 and 0.1 s-1 , and the SA temperature rises with the increase of strain rate. And the disappearance of the third-type dynamic （SA） phenomenon is relevant to the precipitation strengthening of the alloy metals at grain boundaries and in grains. Finally, through systematically analysing the test data, a uniform constitutive model including the third type SA effects was built for DH36 steel. The results predicted by the built model are in agreement with the test data. It displays the built model can well predicate the plastic flow stresses of DH36 steel in the wide ranges of temper- atures and strain rates.