基于奥氏体晶粒超细化的热成形钢组织及相关性能研究

发布时间：2018-12-06 14:09

【摘要】：随着新一代钢铁材料的发展,人们对钢铁结构材料提出了更高的性能要求。其中,热成形钢以其强度高、减重效果明显的特点,成为汽车行业轻量化的关注重点,但强度的提升势必会带来韧塑性的下降,减小了结构件的使用寿命。因此,可以同时提高钢铁材料强度和韧性的细晶强化受到越来越多的关注。本文采用快速感应加热和冷轧的方式,研究了两种成分的Mn-B钢的奥氏体相变规律,探究了不同加热工艺及初始组织对奥氏体晶粒超细化的影响,并对晶粒超细化后的组织与性能进行了研究。首先利用Gleeble-3800热模拟实验和快速感应加热实验对22Mn B5钢进行了快速加热淬火处理。对不同加热工艺下的奥氏体晶粒进行分析,22Mn B5钢在加热至850℃~900℃时,可以获得较为均匀细小且等轴的奥氏体晶粒。研究还表明,在快速感应加热过程中,加热速度的变化对最终晶粒尺寸的影响效果不明显。利用热处理及冷轧制备出铁素体、冷轧铁素体、铁素体+珠光体、冷轧铁素体+珠光体四种不同形态的初始组织,研究了初始组织在快速感应加热过程中的奥氏体相变规律,得到了较为细小的奥氏体晶粒,对淬火组织和晶粒尺寸进行了分析,认为铁素体+珠光体组织相比较而言,更有利于奥氏体晶粒细化。晶粒细化后,强度和韧性都有一定程度的改善,抗拉强度分别提高到970MPa、1100MPa、930MPa和1090MPa,冲击功最大达到了18J。研究表明,奥氏体晶粒的细化,减小了转变后马氏体板条束宽度,增大了裂纹扩展的阻碍作用,提高了裂纹扩展阻力,从而提高了强度和韧性,相比较而言,冷轧铁素体和冷轧铁素体+珠光体钢在快速加热淬火后具有更好的强韧性配比。
[Abstract]:With the development of the new generation of iron and steel materials, people put forward higher performance requirements for steel structure materials. Hot forming steel with its high strength and obvious weight loss effect has become the focus of attention in automobile industry. However, the improvement of strength will inevitably lead to the decrease of ductility and reduce the service life of structural parts. Therefore, more and more attention has been paid to the fine grain strengthening, which can improve the strength and toughness of iron and steel materials at the same time. In this paper, the austenitic transformation of Mn-B steel with two compositions was studied by means of rapid induction heating and cold rolling, and the effect of different heating process and initial microstructure on austenite grain refinement was investigated. The microstructure and properties of ultrafine grain were studied. Firstly, Gleeble-3800 thermal simulation experiment and fast induction heating experiment were used to quench 22Mn B5 steel. The austenite grains of 22Mn B5 steel were analyzed under different heating conditions. When heated to 850 鈩，

本文编号：2366147