中文摘要：

研究淬火和碳再分配（Q＆P）热处理工艺对低碳硅一锰系Q＆P钢的显微组织及精细结构的影响，并和常规工艺实验进行对比。通过SEM，TEM分析，经Q＆P工艺热处理后的钢板可获得板条马氏体和残余奥氏体两相组织，残余奥氏体呈膜状。利用XRD技术并结合软件编程的手段对残余奥氏体进行了定量分析。采用MTS万能拉伸机测定了其力学性能并进行了断口观察，拉伸试样纤维区为比较典型的韧窝状形貌，体现出良好的韧性断裂特征。结果表明：Q＆JP工艺处理后的钢板具有高的抗拉强度（1000MPa以上）和良好的塑性，残余奥氏体在组织中起到了相变诱发塑性的作用。

英文摘要：

Metallurgical microstructure and fine structure were experimentally investigated on the thertoo-mechanical simulator （Gleeble3800）. Lath martensite and retained austenite were obtained in Si- Mn Q＆P steel containing C,Si,Mn through Q＆P process. A large amount of thin films of retained austennite distributed between the lathes of the martensite was detected by means of TEM. The volume fraction of the residual retained austenite based on X-ray diffraction was analyzed quantitatively by the software programmed with VC6.0＋＋. The mechanical properties generated in steels by the Q＆P treatment are studied by MTS electronic tensile testing machine. It is verified that Q＆P steel possesses a good combination of strength and plasticity due to its fine microstructure. It exhibited high ultimate tensile strength （exceeding 1000MPa） and fine elongation of 25%. The fracture mechanism of Q＆P steel was clarified based on examination to the fracture surface of specimens with scanning electronic microscope. The results show that fracture morphology of the low carbon Si-Mn Q＆P steel is a dimple pattern with features of plastic fracture. The retained austennite play a role of phase transformation induced by plastic deformation.