【摘要】 将Mn-Si-Cr系低合金高强钢在过冷奥氏体状态下进行适当预变形,水冷后的组织主要由铁素体、球状碳化物和马氏体组成。研究表明:700℃时的低速率小变形可使上述组织转变为(铁素体+球状碳化物)复相组织,对超塑性变形有利;预变形后水冷的试样在700℃应变速率为10-4 s-1～2×10-4 s-1范围时的m值可达0.48,流变抗力为40～60 MPa,激活能约158 kJ/mol,属于晶界滑动变形机制,具有超塑性变形的特征。更多还原

【Abstract】 An appropriate pre-deformation was applied to a Mn-Si-Cr series low-alloy high strength steel in undercooled austenitic state.The water cooled microstructure after pre-deformation was mainly composed of ferrite,spheroidized carbide and martensite.Low strain rate deformation with a small strain at 700 ℃ can make the above microstructure to transform to dual phase(ferrite plus spheroidized carbide) which is beneficial for superplastic deformation.Within the strain rate range of 10-4 s-1~2×10-4 s-1 at 700 ℃,the water cooled sample after pre-deformation exhibits the following superplastic characteristics: m value reaches 0.48;flow stress lies within 40~60 MPa;and activation energy is about 158 kJ/mol.It is supposed that the deformation mechanism is mainly grain-boundary sliding,and is characteristic of superplastic deformation.更多还原