【作者】 周续；

【导师】 张宏；

【作者基本信息】 长春理工大学 ， 机械制造及其自动化， 2008， 硕士

【摘要】 激光电弧复合焊接是一项新兴的焊接技术,在国外已经发展得相当成熟,而我国在基础研究方面都还存在着许多不足,本文正是在这种背景下,对激光电弧复合焊接进行基础研究。本文采用CO2激光与旁轴MIG电弧进行复合,以7mm厚的高强钢为焊接研究对象,通过扫描电子显微镜、透射电子显微镜、X射线衍射器等设备对焊接接头的微观组织和机械性能进行了系统的研究。研究结果表明:焊缝在结晶过程中发生马氏体相变,其微观组织为马氏体与大量的残余奥氏体;热影响区微观组织为马氏体与残余奥氏体,晶粒明显长大;硬化区有碳化物析出,微观组织为马氏体与少量奥氏体。激光功率的提高使焊缝和热影响区的微观组织晶粒变大,硬度增高;焊接速度的提高使焊缝和热影响区的微观组织晶粒细化,硬度提高;焊接电流和对接间隙的改变对焊缝和热影响区的微观组织影响不大。激光电弧复合焊接能够实现良好的桥联性;焊接接头的抗拉强度高于母材;焊缝硬度低于激光焊接,并且均匀性良好。更多还原

【Abstract】 Laser-arc hybrid welding is a new developing welding technology, which has been well developed abroad, however it is still under the stage of fundamental research in our country. In this paper, the aim of the paper is to study laser-arc hybrid of high-strength steels .In this paper, a CO2 laser combinated with MIGwas used to weld high-strengh steels, the microstructure and mechanical characters were studied systematically by SEM, TEM and XRD etc. The experimental results indicate that martensitic phase transformation takes place in the weld bead during crystallization; its microstructure consist of martensitic and lots of retained austenite;heat affected zone’s microstructure are martensitic and retained austenite,its crystal grain grow larger obviously; harding zone precipitate carbide,its microstructure are martensitic and a few retained austenite; Higher laser power makes the weld bead and heat affected zone’s crystal grain refine, the content of martensitic increase, the hardness becomes higher; higher the speed of welding makes the weld bead and heat affected zone’s crystal grain refine, the content of martensitic increase, the modification of welding current and gap have little influence to the microstructure of the weld bead and heat affected zone. Laserhybrid is able to implement nicer bridging; the tensile strength of the welding joint is higher than the parent metal; the hardness of weld bead is lower than laser, and has a good uniform.更多还原