30CrMnSi钢激光焊接工艺研究

Research on Laser Welding of 30CrMnSi Steel

为减小薄板30CrMnSi钢的焊接变形,提高焊接效率,采用CO2激光对其进行了激光焊接工艺研究。采用激光显微镜、扫描电镜仪对微观组织进行了表征,采用显微硬度计、材料试验机等仪器对性能进行了测试。研究发现,激光焊接后的焊接接头分为焊缝区、热影响区、母材以及焊缝与热影响交界区和热影响与母材交界区5个部分。焊缝与热影响交界区显微硬度最高,母材显微硬度最低。焊接速度越快,焊缝的显微硬度越高,焊缝越窄。焊接速度越快焊接变形越小,激光功率4 kW、焊接速度8 m/min条件下,100 mm长度范围内的变形0.1 mm.激光焊接接头的抗拉强度高于母材110~170 MPa,母材为韧性断裂,断口呈典型的韧窝形态,热影响区发生脆性断裂,断口呈准解理断裂,随着焊接功率和速度的提高,热影响区的拉伸强度有降低的趋势。

The laser welding technology of 30CrMnSi steel welded by CO2 laser was studied in order to reduce its welding deformation and improve its welding efficiency.The microstructure,microhardness and tensile strength of the welding joint were systematically studied by means of SEM,microhardness tester as well as material testing machine.It is found that the welded joint is divided into five parts,such as welding seam zone,heat affected zone,matrix and interface zone between welding seam and heat affected zone,interface zone between matrix and heat affected zone.The microhardness increases from the center of welding joint to the two sides,and is maximized at the interface between the welding seam and heat affected zone.Then it begins to decrease fast at the interface between the heat affected and matrix zone.And the microhardness is minimized at the matrix.The faster the welding speed is,the higher the microhardness of welding seam is,and the narrower the width is.The deformation decreases with the increase in welding speed.The deformation within 100mm length is about 0.1mm when the laser power is 4kW and welding speed is 8m/min.The tensile strength of the welded joint is 110~170MPa higher than matrix.The matrix bears a ductile fracture,and the fracture presents a dimple.A brittle fracture appears in the heat affected zone,and the quasi-cleavage fracture is presented.The tensile strength of the heat affected zone has a decrease tend with the increase in welding speed.