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| Influence of inclusions on fromation of acicular ferrite in 20MnSi steel |
| ZHANG Zhao-hui1，LIU Chuang1，ZHAO Fu-cai1，LIU Shi-feng1，KONG Wei-ming2，QIN Cai-jie1 |
（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） |
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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.
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Received: 05 December 2016
Published: 09 June 2017
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| [1] |
HOU Xin-mei, LIU Yun-song, WANG En-hui. Effect of ladle-lining refractory on non-metallic inclusions in steel[J]. Iron and Steel, 2020, 55(6): 15-24. |
| [2] |
YU Hui-xiang, PAN Ming, YANG De-xin. Behavior of inclusions in ultra-low carbon IF steel during deoxidation and alloying process[J]. Iron and Steel, 2020, 55(6): 46-53. |
| [3] |
NIU Kai-jun, YANG Wen, ZHANG Li-feng, CHU Yan-ping, ZHANG Hong-qi, GUO Zi-qiang. Thermodynamics and industrial practice of formation of inclusions during solidification of tire cord steels[J]. Iron and Steel, 2020, 55(6): 61-67. |
| [4] |
HE Ya-yuan,LI Li-wei,YIN Yun-yang,DENG Zhao-jun. Evolution of microstructure and properties of thickness section of wearresistant steel[J]. JOURNAL OF IRON AND STEEL RESEARCH , 2020, 32(6): 512-518. |
| [5] |
LI Lan-xin1,WANG Min1,JUAN Rong-fei1,BAO Yan-ping1,YANG Jin2. Distribution characteristics of oxides and sulfide inclusions in key areas of gear steel forgings[J]. JOURNAL OF IRON AND STEEL RESEARCH , 2020, 32(5): 370-376. |
| [6] |
QIN Zheng-feng, XUE Zheng-liang, LI Jin-bo, LI Bo-si. Origin of large spherical or bar-shaped inclusions in calcium treated steel[J]. Iron and Steel, 2020, 55(5): 31-38. |
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2017, Vol. 52 
