ABSTRACT

The relationship between the microstructure and mechanical properties of lightweight Al-containing medium-Mn steel with different annealing times was investigated. The results show that the microstructures of the tested steels treated by the I-Q&P process with varying times of annealing are all composed of martensite, α-ferrite, δ-ferrite, and retained austenite. With extended annealing times, the tested steel’s martensite/ferrite microstructure exhibits a variety of size and morphological changes. Simultaneously, retained austenite nucleates and grows at high-angle grain boundaries in ferrite/martensite, exhibiting multi-sized, multi-morphology, and diffuse distribution. With appropriate short annealing times, we achieved improved overall mechanical properties for lightweight Al-containing medium manganese steels than with long annealing times. It allows the tested steel to reach a tensile strength of 1000 MPa, an elongation of 48%, and the product of strength and elongation of 48 GPa·%. At this point, the tested steel shows the best overall mechanical properties.

摘要

研究了不同退火时间的轻质含铝中锰钢的显微组织与力学性能的关系。结果表明，经过不同退火时间IQ&P工艺处理的试验钢的显微组织均由马氏体、α铁素体、δ铁素体和残余奥氏体组成。随着退火时间的延长，测试钢的马氏体/铁素体微观结构表现出各种尺寸和形态变化。同时，残余奥氏体在铁素体/马氏体的大角度晶界处形核和生长，呈现出多尺寸、多形貌和弥散分布。通过适当的短退火时间，与长退火时间相比，我们提高了轻质含铝中锰钢的整体机械性能。使试验钢材的抗拉强度达到1000MPa，伸长率达到48%，强度与伸长率的乘积达到48GPa·%。此时，受试钢材表现出最佳的综合机械性能。