X.J.Xu
,
G.L.Liu
,
L.J.Shi
,
X.N.Cheng
,
L.Cai
金属学报(英文版)
The superplastic deformation characteristics, of commercial 40Cr (i.e., 5140) steel that was water-quenched only 1 times and subsequent high-temperature tempered, were investigated.The results showed that the 40Cr steel has a fine grain of 10-15μm at room temperature,and exhibits a tensile elongation of 304, a true flow stress of 89.3MPa and a strain rate sensitivity m-value of 0.227 at the initial strain rate of 1.0×10^-3s^-1 and at the temperature of 750℃. The final fracture is caused by the development of neck. The experimental result of elongation is in good agreement with the theoretically predicated value according to the analytical expression ef =(1/f )^m exp(nv +me )-1 (where ef, m, f, nv and ε is respectively elongation, average strain rate sensitivity, initial geometric defect, average strain hardening sensitivity at constant deformation velocity and average true strain). The fracture surface is intergraular, and superplastic deformation induces an equiaxed and grown grain. Decreasing strain rate increases tensile elongation and strain rate sensitivity m-value. The primary superplastic deformation mechanism is thought to be atom-diffusion-controlled grain boundary sliding.
关键词:
super plasticity
,
null
,
null
张明明
,
王社良
,
张世民
,
张博
硅酸盐通报
为了研究矿物掺合料对RAC界面性能的改善效果,对174组522个活性矿物增强RAC试件进行力学性能试验,分析了矿物掺合料在不同掺量和体积率下对RAC的力学性能和变形性能影响的变化规律.研究结果表明:粉煤灰FA对RAC立方体的早期抗压强度的影响比较大,且随着掺量的增加,立方体抗压强均有不同程度的降低.随减水剂PS掺量的增加,其降幅增大,随硅粉SF含量的增加,相应降幅随之降低,但对于轴心抗压强度、劈拉强度和抗折强度,增强效果较为明显.随FA、PS和SF含量的变化,峰值应变随之降低,而弹性模量随FA、PS含量的增加而增加.
关键词:
再生混凝土
,
强度比
,
高效减水剂
,
力学性能
