The micromechanical behavior of medium-Mn transformation-induced-plasticity (TRIP) steels with nominal chemical compositions of Fe-0.1C-10Mn (mass%) (0Al steel) and Fe-0.1C-10Mn-2Al (mass%) (2Al steel) fabricated by intercritical annealing 600 °C for 1 h and 650 °C for 1 h, respectively, was investigated using in situ high-energy X-ray diffraction (HE-XRD) with uniaxial tensile tests at 25 °C and 100 °C. We found that Lüders band propagation promoted lower volume fraction of austenite transformation to martensite in 0Al steel than 2Al steel at 25 °C while higher volume fraction of austenite transformation to martensite in 0Al steel than 2Al steel at 100 °C. Portevin-Le Châtelier (PLC) band propagation promoted higher volume fraction of austenite transformation to martensite in 0Al steel than 2Al steel during deformation at 25 °C and 100 °C. Moreover, the addition of Al obviously suppresses the formation of intermediate ε martensite during tensile deformation, thus the zigzag change in lattice strain of austenite was completely depressed in 2Al steel. Due to the controlled stability of metastable austenite, the 2Al steel demonstrated the best combination of ultimate tensile strength and total elongation at 25 °C.

标称化学成分为Fe-0.1C-10Mn（质量％）（0Al钢）和Fe-0.1C-10Mn-2Al（质量％）（2Al）的中锰转变诱导塑性（TRIP）钢的微观力学行为分别使用原位高能X射线衍射（HE-XRD）和在25°C和100° C。我们发现，在25°C时，Lüders带传播促进了0Al钢中奥氏体转变为马氏体的体积分数低于2Al钢，而100°C中0Al钢中奥氏体转变为马氏体的体积分数高于2Al钢。在25°C和100°C变形期间，Portevin-LeChâtelier（PLC）能带传播促进了0Al钢中奥氏体向马氏体转变的体积分数高于2Al钢。此外，Al的添加明显抑制了拉伸变形过程中中间ε马氏体的形成，因此在2Al钢中奥氏体的晶格应变的之字形变化被完全抑制了。由于亚稳态奥氏体具有受控的稳定性，因此2Al钢在25°C时表现出极限抗拉强度和总伸长率的最佳组合。