机械磨擦制备的Fe-20Mn-3Al-3Si钢表面相变强化层  

A PHASE-TRANSFORMATION-STRENGTHENED SURFACE LAYER ON Fe-20Mn-3Al-3Si STEEL FABRICATED BY MECHANICAL GRINDING

作　　者：陈燕[1] 伍翠兰[1,2] 谢盼[1] 陈汪林[1] 肖辉[1] 陈江华[1,2] 

机构地区：[1]湖南大学材料科学与工程学院高分辨电镜中心,长沙410082 [2]湖南大学喷射沉积技术及应用湖南省重点实验室,长沙410082

出　　处：《金属学报》2014年第4期423-430,共8页Acta Metallurgica Sinica

基　　金：国家重点基础研究发展计划项目2009CB623704;国家自然科学基金项目51071064;51171063和51371081;湖南省科研条件创新专项项目2011TT1003资助~~

摘　　要：采用表面机械磨擦处理(SMGT)在Fe-20Mn-3Al-3Si钢的表面制备梯度相变强化层,并研究了该强化层的微观组织和硬度.结果表明,在SMGT过程中,Fe-20Mn-3Al-3Si钢的表层非常容易发生γ→ε→α马氏体相变.SMGT相变受晶粒取向和外力的共同影响:在小载荷SMGT下,晶粒的{111}或者{110}晶面越靠近试样的表面越容易形成片条状组织;在大载荷SMGT下,表层晶粒严重细化,次表层中片条组织最多,然后片条组织数量逐渐减少.室温车削形成的强化层厚度大于400μm,硬度在表面最高(450 HV),然后随深度增加而逐渐下降至基体硬度(约220 HV).另外,SMGT强化层的热稳定性高,经400℃,1 h退火后其微观组织和硬度基本不变.In the last decade, transformation induced plasticity （TRIP） aided steels and twinning induced plasticity （TWIP） aided steels have attracted a great deal of attention due to their high strength and exceptional ductility at room temperature. In the present work, a TRIP/TWlP austenite steel with the composition as Fe-20Mn-3Al-3Si has been investigated by means of surface mechanical grinding treatment （SMGT） since it is an alloy with low stacking fault energy. The ε-M and/or α-M transformations can easily occur in the steel when deformed at room temperature. It is shown that a gradient phase-transformation-strengthened （PTS） surface layer can be formed on bulk Fe-20Mn-3Al-3Si steel by SMGT at room temperature, due to the martensitic transformation of γ→ε→α on its surface. The formation of martensitic phases is dependent on the strain applied and the orientation of grains. The more the { 111 } or the { 110} planes of grains are parallel to the specimen surface plane, the easier the martensitic laths are to be formed in the gains. The total thickness of the PTS surface layer, which formed in the process of turning at room temperature, can be more than 400 μm, but its microstructure and hardness change with depth. The top PTS layer consists of nanometer sized grains while the sublayer contains a great many of martensite laths mixed with deformation twins. With increasing of the depth, the numbers of laths decrease. Correspondingly, the micro-hardness continuously decreases with the depth from 450 HV to about 220 HV （the hardness of the matrix）. The formed PTS layer has a good thermodynamic stability, so that its microstructure and hardness almost do not change after annealed at 400 ℃ for 1 h.

关 键 词：相变强化 表面机械磨擦 高锰钢 应变诱导相变 表面强化 

分 类 号：TG142.33[一般工业技术—材料科学与工程]