加热工艺对16MnCr5H钢奥氏体晶粒度的影响

Effect of Heating Process on Austenite Grain Size of 16MnCr5H Steel

16MnCr5H钢热轧后易产生混晶。为解决这一问题,对16MnCr5H钢分别进行了1 135℃和1 200℃加热2 h空冷,随后在模拟的渗碳温度930℃、950℃和980℃加热6 h油冷,以及分别在模拟的终轧温度840℃、880℃、920℃和980℃加热2 h空冷,再在常用的渗碳温度930℃加热6 h油冷。热处理后,检测了钢的奥氏体晶粒度。结果表明:在1 200℃加热再进行模拟渗碳处理后,16MnCr5H钢中第二相AlN溶解充分,其钉扎奥氏体晶界的作用减弱,导致混晶出现;采用较高的终轧温度能减少16MnCr5H钢的混晶。

16 MnCr5 H steel is easy to produce mixed crystal after hot-rolling. In order to solve this problem, 16 MnCr5 H steel was heated at 1 135 ℃ and 1 200 ℃ for 2 h and air-cooled, respectively, and then heated at simulated carburizing temperatures of 930 ℃, 950 ℃ and 980 ℃for 6 h and oil-cooled, as well as was heated at simulated end-rolling temperatures of 840 ℃,880 ℃,920 ℃ and 980 ℃ for 2 h and air-cooled, and then heated at common carburizing temperature of 930 ℃ for 6 h and oil-cooled. After the heat treating, the 16 MnCr5 H steel was tested for austenite grain size. The results indicated that(a) second phases AlN were fully dissolve in the 16 MnCr5 H steel after heating at 1 200 ℃ followed by simulated carburizing, and their effect of pinning austenite grain boundary weakened, thus exhibiting the mixed crystal;and(b) the use of higher end-rolling temperature was likely to render the mixed crystal in 16 MnCr5 H steel less.