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根据(001)织构极密度的变化测定了控制轧制过程中由应变诱起的奥氏体向铁素体转变的温度Ar_3。基于这些测定,把控制轧制工艺划分为三个阶段:(1)形变再结晶;(2)低温奥氏体形变;(3)奥氏体——铁素体双相区形变。对各阶段形变得到的金相组织和力学性能进行了检验。在1000℃以上第一阶段,奥氏体晶粒尺寸通过反复的再结晶而减小。在第二阶段,950℃至Ar_3转变温度之间,奥氏体晶粒被拉长,并产生大量的形变带,结果得到很细小的铁素体晶粒尺寸。在第三阶段,稍低于Ar_3温度,新形成的铁素体晶粒发生形变,得到较高的强度和较低的脆性转变温度。由第二阶段形变得到的强度和冲击转变温度,仅取决于细小的铁素体晶粒尺寸。为获得更高的强度和更低的冲击转变温度,继而进行第三阶段的形变是必要的。
According to the change of (001) texture density, the temperature Ar_3 of the strain induced austenite to ferrite transformation was measured. Based on these measurements, the control rolling process is divided into three stages: (1) deformation recrystallization; (2) low temperature austenite deformation; (3) austenite-ferrite two-phase zone deformation. The deformation of the microstructure and mechanical properties of the various stages were tested. In the first stage above 1000 ° C, austenite grain size decreases through repeated recrystallizations. In the second stage, between 950 ° C and the Ar_3 transformation temperature, the austenite grains are elongated and produce a large amount of deformation zone, resulting in very small ferrite grain size. In the third stage, slightly lower than the Ar_3 temperature, the newly formed ferrite grains deform to obtain higher strength and lower brittle transition temperature. The strength and impact transition temperature resulting from the second-stage deformation depend only on the fine ferrite grain size. To obtain higher strength and lower impact transition temperature, followed by the third stage of deformation is necessary.