铝硅合金化耐候钢的晶粒细化和组织控制

Grain Refinement and Microstructure Control of Al-Si Bearing Weathering Steel

通过热模拟试验研究了铝硅合金化耐候钢在形变强化相变及冷却过程中的组织演变规律。结果表明,其组织演变符合低碳钢形变强化相变的基本规律,形变温度较低时,铁素体转变量较高,晶粒尺寸较小。奥氏体晶粒细化促进形变强化相变过程的发生。经高温奥氏体和形变强化相变两道次变形并控制后续冷却工艺可以获得细晶铁素体和不同第二组织——直接淬火为铁素体(F)+马氏体(M),以30℃/s冷却为铁素体(F)+贝氏体(B),以2℃/s冷却为铁素体(F)+珠光体(P)。当冷却速度大于30℃/s时,细晶铁素体长大不明显。

The microstructure evolution of Al-Si bearing weathering steel during deformation-enhanced transformation and subsequent cooling was studied by means of hot compression simulation experiment. The results show that similar characteristics of the microstructure evolution in this kind of steel are found compared with low carbon steeL With the dccreaes of deformation temperature, the ferrite volume fraction increases and the ferrite grain size decreases. The deformation enhanced transformation will be promoted due to the refinement of austenite grain size. Multiphase microstructure of finer ferrite and different minor microstructure are obtained by applying two-pass deformation at austenite and undercooled austenite region combining with subsequent controlled cooling. As quenching the minor microstructure is martensite. When the cooling rate is 30℃/s, bainite can be achieved. While pearlite is formed at the cooling rate of 2℃/s. When the cooling rate exceeds 30℃/s, no obvious growth are observed in finer ferrite grains.