Ni Mao, Hu Zeqi, Qin Xunpeng, Xiong Xiaochen, Ji Feilong
Hubei Key Laboratory of Advanced Technology for Automotive Components, Wuhan University of Technology, 122 Luoshi Road, Wuhan 430070, China.
School of Automotive Engineering, Wuhan University of Technology, Wuhan 430070, China.
Materials (Basel). 2023 Mar 27;16(7):2639. doi: 10.3390/ma16072639.
Hot forging dies are subjected to periodic thermal stress and often fail in the forms of thermal fatigue, wear, plastic deformation, and fracture. A gradient multi-material wire arc additive remanufacturing method for hot forging dies was proposed to extend the service life of hot forging dies and reduce total production costs. The properties of multi-material gradient interfaces play a critical role in determining the overall performance of the final products. In this study, the remanufacturing zone of a hot forging die was divided into three deposition layers: the transition layer, the intermediate layer, and the strengthening layer. Experiments of wire arc additive manufacturing with gradient material were conducted on a 5CrNiMo hot forging die steel. The microstructure, microhardness, bonding strength, and impact property of gradient interfaces were characterized and analyzed. The results revealed that the gradient additive layers and their interfaces were defect-free and that the gradient interfaces had obtained a high-strength metallurgical bonding. The microstructure of the gradient additive layers presented a gradient transformation process of bainite-to-martensite from the bottom to the top layer. The microhardness gradually increased from the substrate layer to the surface-strengthening layer, forming a three-level gradient in the range of 100 HV. The impact toughness values of the three interfaces were 46.15 J/cm, 54.96 J/cm, and 22.53 J/cm, and the impact fracture morphology ranged from ductile fracture to quasi-cleavage fracture. The mechanical properties of the gradient interfaces showed a gradient increase in hardness and strength, and a gradient decrease in toughness. The practical application of hot forging die remanufactured by the proposed method had an increase of 37.5% in average lifespan, which provided scientific support for the engineering application of the gradient multi-material wire arc additive remanufacturing of hot forging dies.
热锻模具承受周期性热应力，常因热疲劳、磨损、塑性变形和断裂等形式失效。提出了一种用于热锻模具的梯度多材料电弧增材再制造方法，以延长热锻模具的使用寿命并降低总成本。多材料梯度界面的性能在决定最终产品的整体性能方面起着关键作用。在本研究中，将热锻模具的再制造区域分为三个沉积层：过渡层、中间层和强化层。在5CrNiMo热锻模具钢上进行了梯度材料电弧增材制造实验。对梯度界面的微观结构、显微硬度、结合强度和冲击性能进行了表征和分析。结果表明，梯度增材层及其界面无缺陷，梯度界面获得了高强度冶金结合。梯度增材层的微观结构呈现出从底层到顶层贝氏体到马氏体的梯度转变过程。显微硬度从基体层到表面强化层逐渐增加，在100 HV范围内形成三级梯度。三个界面的冲击韧性值分别为46.15 J/cm、54.96 J/cm和22.53 J/cm，冲击断口形貌从韧性断裂到准解理断裂。梯度界面的力学性能表现为硬度和强度梯度增加，韧性梯度降低。采用该方法再制造的热锻模具实际应用中平均寿命提高了37.5%，为热锻模具梯度多材料电弧增材再制造的工程应用提供了科学支撑。
