Fe-20Mn-2.6Al-2.6Si钢拉伸变形机理研究

采用金相显微镜、X射线衍射仪和透射电子显微镜研究了Fe-20Mn-2.6Al-2.6Si TRIP/TWIP钢在不同变形量下的微观组织变化.结果表明:在应变初期,主要是形成层错和位错;随应变的增大,γ奥氏体相逐渐减少,ε马氏体相和α马氏体相增多;在断裂阶段,主要组成相为α马氏体,即Fe-20Mn-2.6Al-2.6Si钢在拉伸变形过程中主要发生γ→ε→α或γ→α相变诱导塑性变形.金相组织表明:该钢变形量达到6.5%时,开始出现许多平直的条纹(通常称为形变孪晶);但高分辨透射电镜研究表明:不同程度变形后的微观组织都难以观察到形变孪晶,而那些金相组织和低倍透射电镜照片上的平直条纹往往是ε马氏体相,这进一步证实该钢的变形机制主要是TRIP效应.

Tensile Deformation Mechanism of Fe-20Mn-2.6Al-2.6Si Steel

The microstructure evolution of the Fe-20Mn-2.6Al-2.6Si TRIP/TWIP steel with different deformation levels was studied with optical microscopy,X-ray diffraction and transmission electron microscopy.The results indicated that stacking faults and dislocation cells were primarily formed at the initial stage of deformation.The contents of the α martensite and ε martensite were gradually increasing with the strain increasing.At the last stage,the α martensite becomes the main phase.So,the tensile deformation mechanism of the Fe-20Mn-2.6Al-2.6Si steel was the phase transformation inducing the deformation(TRIP).The optical microscopy morphology showed that many lamellas appeared when the deformation level was up to 6.5%,and these lamellas were usually mistaken for deformation twins.But the transmission electron microscope(TEM) analysis indicated that deformation twins were hardly found at any of the deformation levels.Actually,the lamellas observed in the optical microscopy or low magnification TEM images were ε phase,which further confirms that the deformation mechanism of the Fe-20Mn-2.6Al-2.6Si TRIP/TWIP steel was the TRIP mechanism.