纳米强化钢激光-GMA复合焊接热影响区的相变机理及性能调控

项目名称： 纳米强化钢激光-GMA复合焊接热影响区的相变机理及性能调控

项目编号： No.51305285

项目类型： 青年科学基金项目

立项/批准年度： 2014

项目学科： 机械、仪表工业

项目作者： 王晓南

作者单位： 苏州大学

项目金额： 25万元

中文摘要： 作为光制造领域的研究前沿，光纤激光-GMA复合焊接技术为具有广阔应用前景的新型热轧纳米强化钢（屈服强度600-700MPa级）提供了一种新的连接方法，解决常规MAG焊接接头热影响区韧性及抗疲劳性能骤降的问题。通过光纤激光-GMA复合焊接过程中焊接接头热影响区微观组织相变机理的研究，揭示纳米强化相(Nb,Ti)C在热影响区内的回溶、粗化及再析出规律，确定纳米强化相(Nb,Ti)C在热影响区中的回溶区、粗化区及再析出区；通过焊接接头热影响区微观尺度力学性能的研究，将焊接接头热影响区微观组织尤其是纳米强化相(Nb,Ti)C与宏观尺度力学性能联系起来，揭示微观组织与力学性能的相关性和内在的规律性；最终确定热影响区最优微观组织及相应焊接工艺制度。项目的实施，有望提升新型热轧纳米强化钢焊接质量，拓展光纤激光-GMA复合焊接技术应用领域，从而有力提升我国在该前沿领域的研究水平。

中文关键词： 激光焊接；激光-电弧复合焊接；相变机理；显微组织；力学性能

英文摘要： As the research frontier of optical manufacture, the hybrid fiber laser gas metal arc (GMA) welding provides a new jointing method for the new type hot-rolled nano-scale precipitate strengthened steel (whose yield strength range is 600-700MPa), giving a solution to the problem of the plummeting of anti-fatigue and toughness of the heat affected zone for matal active gas (MAG) welding. By studying the phase transformation mechanisms of microstructure at the heat affected zone of the hybrid fiber laser-GMA welding, the regularities of re-dissolution, coarsening, and re-precipitation of nano-scale precipitate strengthened phase (Nb,Ti)C is revealed, thus identifying the respective areas of re-dissolution, coarsening, and reprecipitation at the heat affected zone of the nano-scale precipitate strengthened phase (Nb,Ti)C. By learning the micro-scale mechanical properties of the heat affected zone in the welded joints, this thesis links the variations of microstructure, especially the nano-scale precipitate strengthened phase (Nb,Ti)C to the macro-scale mechanical properties, thereby revealing the inherent regularities and correlations between the microstructure and the mechanical properties, and identifying the optimal microstructure of heat affected zone and related technological process of welding. The implementati

英文关键词： Laser welding；Laser arc hybrid welding；Phase transformation mechanism；Microstructure；mechanical property