中文摘要：

为了研究激光焊接对5mm厚异种材料45^#钢与40Cr钢焊接的接头组织性能影响,利用6kW高功率激光器在不同参数下进行拼焊试验,采用佳能7D型单反相机拍摄焊缝表面宏观形貌,采用X-350A型应力测定仪检测垂直焊缝方向的表面残余应力,通过HXD-1000型显微硬度计检测焊缝深度方向的显微硬度。结果表明：相对其余情况,焊接速度为1.2m/min时,焊缝表面形貌形状饱满,气孔等缺陷少,表面质量最好;离焦量为-2mm,热输入量为210J/mm时焊缝区出现高而窄的压应力分布,最大值为-187 MPa,能有效提高焊缝疲劳性能;离焦量为-2、-4mm和0mm三种情况时焊缝区整体显微硬度都比母材区高,并且离焦量为-2mm时硬度分布最好,呈平缓减小趋势,最大值为38 HRC,比母材平均值高出14 HRC。选择适当的激光焊接参数能有效的改善45#钢与40Cr钢焊接接头组织性能。

英文摘要：

In order to study the influence of laser welding 5 mm thick 45 steel and 40Cr steel,this paper uses 6kw high power laser to contact welding test under different elements. Macro performance of weld surface is observed by canon 7D SLR camera and residual stress is measured by X-350A stress meter along the vertical direction of weld joint, and HXD-1000 micro-hardness tester is used to detect the micro-hardness along the depth direction. The result shows that relative to other situations, when the welding speed is 1.2 m/min, macro performance’s form shows plump and nearly has spots and holes. When the defocusing amount is -2 mm and the heat input is 210 J/mm, residual stress on the weld surface performances a good distribution of compressive stress, which is high and narrow, and the maximum is -187 MPa. Under this condition that the defocusing amounts are -2 mm、-4 mm and 0 mm, the hardness of weld area are all higher than base metal. The stress distribution is better than others when the defocusing amount is -2 mm, of which the variation trend gently decreases and the maximum is 38 HRC about 14 HRC higher than the base metal’s average value. So suitable laser parameters can effectively improve the structure property of the welded joint of 45 steel and 40Cr steel.