w(Co)对CB2钢显微组织和力学性能的影响

为研究w(Co)对CB2钢微观组织和力学性能的影响，调整CB2钢中w(Co)为0.5%，1.0%，1.5%，2.0%和3.0%.利用光学显微镜(OM)、扫描电镜(SEM)、室温拉伸等检测方法研究w(Co)对试验钢微观组织和力学性能的影响规律，结合Thermo-Calc和JMatpro-7.0模拟结果解释其影响机理.研究发现:w(Co)增加提高铬当量的值，使试验钢中δ铁素体含量减少，当w(Co)增加到1.5%时，δ铁素体基本消失;材料的抗拉强度随w(Co)的增加而增加，而延长率则先增加后降低;结果表明，w(Co)为1.5%时综合性能较好，即抗拉强度达到805.13MPa，延长率达到20.4%，布氏硬度为260.

Effect of Co Content on Microstructure and Mechanical Properties of CB2 Steel

In order to study the effect of Co content on microstructure and mechanical properties of the CB2 steel， the contents of Co in CB2 steel were adjusted to 0.5%， 1%， 1.5%， 2% and 3%， respectively. Using optical microscope (OM)， scanning electron microscopy (SEM)， and tensile test at room temperature， the effect of different Co content on the microstructure and mechanical properties was studied， associated with the Thermo-Calc and JMatpro-7.0 simulations. It is found that when the content of Co in the steel increases， the chromium equivalent value increases and the δ-ferrite content decreases. Especially， when the content of Co is 1.5%， the δ-ferrite is appears. Meanwhile， with the increase of Co content， the tensile strength of the steel increases， while the elongation increases firstly and then decreases. The results indicate that the steel with the Co content of 1.5%has a good comprehensive property， where the ultimate tensile strength reaches 805.13MPa， and the elongation is 20.4% and Brinell hardness is 260， respectively.