材料期刊网

对HSLA-65, DH-36, AL-6XN和Nitronic-50这4种新型舰艇结构钢的力学行为进行了系统研究. 实验的温度变化范围从77 到1000 K, 应变率从0.001到8000 s-1, 真实塑性应变超过40%. 结果表明：(1)这4种结构钢的塑性流变应力对温度和应变率非常敏感, 流变应力随温度的降低和应变率的增加而提高；(2)随塑性应变的增加或变化, 温度历史会显著引起fcc金属内部微观结构演化；(3)在适当的温度和加载应变率范围, 动态应变时效现象发生, 且随应变率提高, 动态应变时效出现的温区移向更高区域. 针对实验所出现的这些现象, 并考虑到塑性流变的粘-曳阻力,根据位错运动机理, 给出了一个基于物理概念的本构模型, 此模型未涉及动态应变时效现象. 通过比较模型预测结果和实验结果, 在很宽温度范围和很宽应变率范围内, 所给出的本构关系能够较好的预测这4种新型舰艇结构钢的塑性流变应力.

In the present paper, mechanical behavior of HSLA-65, DH-36, AL-6XN and Nitronic-50 is systematically studied. Strains over about 40% are achieved in these tests over a temperature range of 77-1,000K and strain rates of 0.001 to 8,000/s. The results show that, 1) Plastic flow stress of the four newer steelsis is sensitive to the temperature and strain rate, flow stress decreases with decreasing temperatures and increasing strain rates; 2) With increasing or changing plastic strain, the temperature history remarkably affects the microstructure; 3) Dynamic strain aging occurs at lower strain rates and higher temperatures. With increasing strain rates, the stress peak of dynamic strain aging will shift to higher temperature region, or even disappear in the present strain rate range. Taking into account all these phenomena, based on the mechanism of dislocation motion, including the effect of viscous drag on the motion of dislocations, the physically-based model is shown, but excluding the dynamic strain aging effects, The parameters of this model contain the physical concept. Finally, the results of model is discussed. The model predictions are compared with the results of the experiments in a wide range of temperatures and strain rates, but excluding plastic flow stresses in dynamic strain aging region.