EA4T steel surface of damaged axles was repaired by laser cladding.The microstructure of the laser cladding was analyzed by using optical microscopy,scanning electron microscopy and X-ray.The binding properties between matrix and cladding layer and the residual stresses of the laser cladding were examined by universal testing machine and stress testing instrument.The results shows that the microstructures of laser cladding layers are mainly composed of γ-Fe solid solution,BNi3,M7C3 and Fe3C.The microstructure of the heat affected zone is composed of fined bainite and network ferrite.The binding region is mainly formed by Crystal,columnar crystals and dendrites.The microstructures of top region of cladding layer are mainly cross dendrite crystals.After laser cladding,the tensile strength of EA4T steel increases,while the yield strength and U-notch impact properties at room temperature decrease.Residual tensile stress exists in cladding layer and residual stress in the substrate is compressive stress.%通过激光熔覆技术对损伤车轴EA4T钢表面进行修复,利用光学显微镜、扫描电镜和X线衍射方法分析修复层的显微组织结构,利用万能拉伸试验机和应力测试仪测试修复层和基体的结合性能及残余应力.研究结果表明:修复层显微组织主要由γ-Fe固溶体、BNi3、M7C3和Fe3C组成,热影响区为上贝氏体和呈网状分布的铁素体组织,修复层和基体的结合区主要由平面晶、柱状晶和树枝晶组成,修复层顶部区域其组织主要以交叉树枝晶为主;激光熔覆后的EA4T钢的抗拉强度升高,但屈服强度和常温U型缺口冲击性能降低;整个修复层中残余应力较大,呈拉应力状态分布,而基体区域呈压应力状态分布.
展开▼
