摘要
对23Co14Ni12Cr3钢利用高精度、高稳定性电阻仪及X射线衍射技术，首次发现在一定温度以上等温形成的逆转变奥氏体量会显著地影响随后冷却过程中马氏体转变的程度，同时确定出产生这一现象的最低温度。进一步对该钢于不同温度下保温不同时间后进行X射线衍射分析并测其逆转变奥氏体量.基于奥氏体形成初期其体积分数与等温时间间近似成线性关系的特点，给出了一种确定不同等温温度下逆转变奥氏体开始形成时间的新方法，获得了在相同转变量下的奥氏体等温形成动力学图（即TTA图）。结果表明：随加热速度下降，As温度逐渐降低并最终过渡为Ad，由此澄清了长期令人混淆的As与Acl间的区别并建立起两者间的联系.
Above a certain temperature,the volume fraction of austenite formed during isothermal period will remarkably affect the degree of martensitic transformation in the course of later cooling for steel 23Co14Ni12Cr3 thrugh a kind of resistance instrument with high precision and stability and X-ray diffraction technology.The lowest temperature on this phenomenon was determined in the meantime.Furthermore,several specimens of steel held at different temperature through different time were analyzed and the content of reverted austenite was measured by X-ray diffraction at room temperature.Based on the characteristic of linear relationship between volume fraction of reverted austenite and isothermal time during initial stage of isothermal process,a new method is proposed for determining the first formation time of reverted austenite in case of several isothermal temperature.The results of experiment show that with heating rate being lowered,temperature would drop gradually and eventually become critical temperature Acl.The difference between As and Acl is thus clarified,and a new connection between them is established.
出处
《材料科学与工艺》
EI
CAS
CSCD
1998年第2期98-102,共5页
Materials Science and Technology
基金
航空基础科学基金
关键词
等温转变
孕育期
动力学
钢
奥氏体形成
isothermal transformation
incubation period
A_s temperature
critical temperature A_(cl)
