【摘要】：隨著新一代鋼鐵材料的發(fā)展,人們對(duì)鋼鐵結(jié)構(gòu)材料提出了更高的性能要求。其中,熱成形鋼以其強(qiáng)度高、減重效果明顯的特點(diǎn),成為汽車行業(yè)輕量化的關(guān)注重點(diǎn),但強(qiáng)度的提升勢(shì)必會(huì)帶來韌塑性的下降,減小了結(jié)構(gòu)件的使用壽命。因此,可以同時(shí)提高鋼鐵材料強(qiáng)度和韌性的細(xì)晶強(qiáng)化受到越來越多的關(guān)注。本文采用快速感應(yīng)加熱和冷軋的方式,研究了兩種成分的Mn-B鋼的奧氏體相變規(guī)律,探究了不同加熱工藝及初始組織對(duì)奧氏體晶粒超細(xì)化的影響,并對(duì)晶粒超細(xì)化后的組織與性能進(jìn)行了研究。首先利用Gleeble-3800熱模擬實(shí)驗(yàn)和快速感應(yīng)加熱實(shí)驗(yàn)對(duì)22Mn B5鋼進(jìn)行了快速加熱淬火處理。對(duì)不同加熱工藝下的奧氏體晶粒進(jìn)行分析,22Mn B5鋼在加熱至850℃~900℃時(shí),可以獲得較為均勻細(xì)小且等軸的奧氏體晶粒。研究還表明,在快速感應(yīng)加熱過程中,加熱速度的變化對(duì)最終晶粒尺寸的影響效果不明顯。利用熱處理及冷軋制備出鐵素體、冷軋鐵素體、鐵素體+珠光體、冷軋鐵素體+珠光體四種不同形態(tài)的初始組織,研究了初始組織在快速感應(yīng)加熱過程中的奧氏體相變規(guī)律,得到了較為細(xì)小的奧氏體晶粒,對(duì)淬火組織和晶粒尺寸進(jìn)行了分析,認(rèn)為鐵素體+珠光體組織相比較而言,更有利于奧氏體晶粒細(xì)化。晶粒細(xì)化后,強(qiáng)度和韌性都有一定程度的改善,抗拉強(qiáng)度分別提高到970MPa、1100MPa、930MPa和1090MPa,沖擊功最大達(dá)到了18J。研究表明,奧氏體晶粒的細(xì)化,減小了轉(zhuǎn)變后馬氏體板條束寬度,增大了裂紋擴(kuò)展的阻礙作用,提高了裂紋擴(kuò)展阻力,從而提高了強(qiáng)度和韌性,相比較而言,冷軋鐵素體和冷軋鐵素體+珠光體鋼在快速加熱淬火后具有更好的強(qiáng)韌性配比。
[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，

本文編號(hào)：2366147