采用激光送丝堆焊技术对预置缺陷(缺陷深度0.4、0.8、1.2、1.6和2.0 mm, 样品厚度4 mm)的30CrMnSiNi2A超高强度钢进行修复, 对激光功率、激光扫描速度、送丝速度进行正交试验得出最佳工艺, 以获得性能优良的修复样品。利用光学显微镜(OM)、电子扫描显微镜(SEM)、显微硬度仪和万能试验机对修复件熔池尺寸、显微组织、显微硬度、抗拉强度和拉伸断口进行了研究。结果表明, 1.2 mm缺陷深度, 激光功率3.1 kW, 焊接速度0.9 m/min, 送丝速度2.4 m/min时, 修复件性能最佳, 抗拉强度达到原件设计标准, 断口出现在堆焊层。工艺参数影响着熔池质量尺寸参数, 包括熔深、堆焊层宽度和堆高, 从而影响修复件质量。根据缺陷深度, 采用各自的最佳工艺, 在预置缺陷深度0.4 mm、0.8 mm和1.2 mm的样品中, 抗拉强度基本达标, 超过1.2 mm时, 抗拉强度急剧下降,不达标。由此得到预置缺陷的样品临界修复尺寸是1.2 mm, 即占板厚的30%。

The ultra-high strength steel 30CrMnSiNi2A with preset defects(damage depth: 0.4 mm, 0.8 mm, 1.2 mm, 1.6 mm and 2.0 mm, sample depth: 4 mm)was repaired by laser wire-feeding surfacing welding technology, laser power, laser scanning speed, wire feed speed orthogonal experiments were performed to obtain the best process for excellent repaired samples. The molten pool size, microstructure, microhardness, tensile strength and fracture were investigated by means of optical microscopy(OM), scanning electron microscopy(SEM), microhardness testing machine and electronic universal testing machine. The results show that with a damage depth of 1.2 mm, laser power of 3.1 kW, welding speed of 0.9 m/min and the wire feed speed of 2.4 m/min, the repaired parts perform best, the tensile strength meets the original design criteria, and the fracture appears on the surfacing layer. The process parameters affect the quality parameters of the molten pool, including the penetration depth, the width of the surfacing layer and the height of the pile, thereby affecting the quality of the repaired parts. According to the depth of defects, using their best technology, the tensile strength of the samples with pre-defective depths of 0.4 mm, 0.8 mm, and 1.2 mm basically meets the standard. When the depth exceeds 1.2 mm, the tensile strength decreases sharply and fails to reach the standard. The critical repair dimension of a sample with a preset defect is 1.2 mm, which is 30% of the plate thickness.