4种新型舰艇钢的塑性流变应力及其本构模型

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1000K，应变率从0．001到8000s^-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一曳阻力，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．

Plastic low stress and physically based constitutive model of four newer naval vessel steels

The mechanical behaviors of the steels HSLA-65, DH-36, AL-6XN and Nitronic-50 were systematically studied at strains over 40%, a temperature range of 77-1000 K and strain rates of 0.001 to 8000 s-1.The results are as follows (1) plastic flow stresses of the four steels are all very sensitive to the temperature and strain rate, the flow stresses increased with decreasing temperatures and increasing strain rates; (2) with plastic strain increasing or changing, the temperature history remarkably evolved the microstructure of fcc metals; (3) dynamic strain aging occured in proper temperature and strain rate region. With increasing strain rate, the temperature region of dynamic strain aging will shift to higher. Taking into account these phenomena, based on the mechanism of dislocation motion, including the effect of viscous drag on the motion of dislocations, physics based model was given in which the dynamic strain aging effects were excluded. Comparing the results predicted and measured, good agreement is obtained for the plastic flow stresses of these steels in a wide range of temperatures and strain rates.