（1. College of Metallurgical Engineering， Xi’an University of Architecture and Technology， Xi’an 710055， Shaanxi，China 2. Central Iron and Steel Research Institute， HBIS， Shijiazhuang 050023， Hebei， China）
Abstract：Phase transformations of 20MnSi steel during a continuous cooling process were examined through thermal simulation experiments. Samples with intracrystalline acicular ferrite （IAF） were obtained via deoxidization by adding CaC2， silicon-calcium wire and heat treatment. Additionally， the microhardness of the IAF area was determined through a microhardness tester， and the IAF microstructure was observed with an optical microscope. The inclusion properties that induced IAF nucleation were analyzed by a scanning electron microscope and energy dispersive spectrometry. The results showed that the cooling rate of IAF formation in 20MnSi steel was in the range of 5-20 ℃/s. Furthermore， inclusions that could induce the nucleation of intracrystalline acicular ferrite were mainly composed of MnS， followed by MnO·SiO2 and MnS·SiO2. The size of the three types of inclusions were primarily <3 μm. The nucleation of IAF induced by MnS was determined by stress-strain energy and inert interfacial energy. Heating at high temperature and isothermal heat preservation may lead to a reduced or absent Mn-depleted zone （MDZ）， which is not conducive to the formation of acicular ferrite. Inclusions with high melting temperature could contribute to the nucleation of acicular ferrite. Composite inclusions and inclusions as inlays may be able provide more suitable nucleation areas for acicular ferrite， and promoted the nucleation and subsequent growthof the additional acicular ferrite.
收稿日期: 2016-12-05
出版日期: 2017-06-09
引用本文:
张朝晖，刘 创，赵福才，刘世锋，孔维明，秦偲杰. 20MnSi中夹杂物对针状铁素体形成的影响[J]. 钢铁, 2017, 52(6): 87-93.
ZHANG Zhao-hui，LIU Chuang，ZHAO Fu-cai，LIU Shi-feng，KONG Wei-ming，QIN Cai-jie. Influence of inclusions on fromation of acicular ferrite in 20MnSi steel. Iron and Steel, 2017, 52(6): 87-93.
2017, Vol. 52 
