【摘要】 采用高分辨率的径迹显微照相技术,研究了淬火硼钢中硼向奥氏体晶界偏聚的规律,定量地测定出跨过奥氏体晶界的硼的成分剖面图以及非平衡晶界偏聚的特征参量(晶界贫硼区宽度、晶界富集程度和富集带宽度)。试验表明,这种偏聚具有如下特征: 在偏聚晶界的两侧存在有一定宽度的贫硼区,晶界偏聚的硼是在冷却过程中由该区富集而来;这种偏聚对冷却速度很敏感,急速冷却可以抑制这种偏聚。冷却速度降低,晶界偏聚由连续的偏聚带,逐步发展为不连续的聚集直至明显地析出硼相,贫硼区宽度与冷却速度的平方根成反比;它的温度关系与晶界平衡偏聚预言相反,随淬火温度升高,晶界偏聚程度与贫硼区宽度增加。通过试验,论证了淬火钢中硼向奥氏体晶界的偏聚,是在冷却过程中发生的一种非平衡的晶界偏聚现象。更多还原

【Abstract】 By means of high resolution particle-tracking autoradiography the regularity of boron segregation to austenite grain boundaries has been studied, and the boron concentration profiles across segregated grain boundaries and characteristic parameters for non-equilibrium grain boundary segregation (width of boron-depleted zone, degree and width of boron-segregated band) have been measured. It has been shown that this kind of grain boundary segregation has following features:There exists boron-depleted zone adjacent to segregated grain boundary, which is responsible for supplying of boron to grain boundary during cooling. This kind ofl segregation during cooling is very sensitive to cooling rate. Rapid cooling can inhibit it, and the segregation state would progressively develop from continuous band to discontinuous aggregation and even apparent precipitation as cooling rate decreases. The width of boron-depleted zone is inversely proportional to the square root of cooling rate. The temperature relationship of segregation opposites to the expectation of equilibrium grain boundary segregation. The higher the quenching temperature, the more incremental are the segregated degree and the width of boron depleted zone.The test has been demonstrated that the boron segregation at austenite grain boundaries in quenched steel is a non-equilibrium grain boundary segregation phenomena occurred during cooling.更多还原