【作者】 宋卓霞；

【导师】 张贵杰；

【作者基本信息】 河北理工大学 ， 材料加工工程， 2009， 硕士

【摘要】 Fe-Mn-C合金由于其较高的强度和塑性以及较好的耐磨性,在许多行业中有着重要的应用,然而,迄今为止,对Fe-Mn-C合金的结构与性能的宏观和微观机理研究尚没有统一的结论。本文从实验和计算模拟对其进行了研究。由于模拟体系与实验材料存在差异,在实验方面,对Fe-Mn-C合金中的高锰钢为研究对象,利用透射电镜,原子力显微镜等测试方法,对不同形变量的高锰钢组织演变的晶体学机制及磨损规律进行了分析。在模拟计算方面,采用“Material Studio”材料计算中的CASTEP子模块程序,以Fe-Mn-C系合金为研究对象,对随着Mn,C含量的变化,Fe-Mn-C系合金性能的变化规律进行了理论预测,为该合金的进一步研究提供理论依据。研究结果表明:1)在较小形变量情况下,组织中开始出现很多平直的变形带以及孪生变形,位错组态表现为平直的条带;随着形变量的增加,组织中孪晶的数量明显增多,当形变量达到一定程度后,组织中孪晶的数量增加速率开始下降,孪晶内出现少量的次生孪晶。2)形变量小于20%时,经冷轧的高锰钢随着形变量的增加,其耐磨性能也随之增加,这是因为深度冷轧的高锰钢表面形成的高密度位错及孪晶组织能有效阻止磨损表面的脆性剥落,同时,高锰钢良好的心部韧性也将减少其磨损过程中的疲劳剥落;形变量大于20%时,随着形变量的增加,耐磨性降低,这是由于随着形变量增加高锰钢表面在形成高密度位错及孪晶组织的同时,使裂纹逐渐形成和扩展,这在一定程度上会使其耐磨性下降。3)随着Mn含量增加,弹性系数C1 1增大, C1 2和C 44减小,体弹性模量B和剪切弹性模量G随着C,Mn含量的增加都有所增加。Fe-Mn-C合金的层错能较低,并且随着Mn含量的增加层错能增加。更多还原

【Abstract】 Fe-Mn-C Alloys played an important role in many industries,but have not yet reached unified conclusion until now about the research of Macro and microcosmic mechanism.The paper studies it from calculation and experiments.It is different between simulation system and experimental materials.At the experimenntal level, wear behaviors of the high manganese steel under the condition of different rolling reduction rates.observed by TEM, AFM and other general test methods. At the simulation level, Using CASTEP calculation program, studying the performances of different C, Mn contents in Fe-Mn-C austenitic alloys were theoretically forecasted.The research work made it possible for further study as theoretical basis. The research indicates:1) The straight distortion belts as well as the twin distortion start to present at the small deformation, and the dislocation configuration exhibits for the straight banding. Along with deformation quantity’s augmentation, the twin crystals quantity increases and the twin crystals density increases obviously. After the reduction quantity achieves the certain extent, twin crystals quantity increasing rate tends to slow down, and a few secondary twin crystals present in the twin crystals.2) Wear resistance increased with the reduction rates increasing when deformation is less than twenty percent.The reasons are high manganese steel by severe cold-rolling form a high density of dislocation and the twins.They can effectively prevent the surface of brittle spalling caused by abrasive wear.At the same time,good toughness in center of High-manganese steel will reduce the fatigue spalling in the process of abrasive. Because of Crack expansion, wear resistance reduced with the reduction rates increasing when reduction is more than twenty percent.3) With the Mn content increasing, the C1 1 and Elastic moduli increased, but C1 2 and C 44decreased. B and G increased with the C Mn content increasing Fe-Mn-C alloy have low stacking fault energy, and they increased with the Mn content increasing.更多还原