激光增材制造H13钢及回火处理的组织和性能

Microstructure and Properties of Laser Additive Manufacturing and Tempered H13 Steel

利用激光增材制造技术成功制备了H13钢,并研究了回火处理对其显微组织和性能的影响。通过光学显微镜、SEM以及XRD衍射仪对各试样进行分析。结果表明,激光增材制造H13钢显微组织主要为马氏体、残余奥氏体以及细小碳化物,回火处理使得马氏体向回火马氏体转变,同时有细小合金碳化物析出。当回火温度超过550℃时,碳化物开始粗化。随回火温度升高,显微硬度呈先升后降的趋势。550℃回火后,试样硬度达到峰值600 HV_(0.3)。摩擦磨损测试结果表明,不同处理状态下各试样主要以粘着磨损为主,同时包含轻微氧化磨损。与沉积态试样相比,550℃回火后,试样耐磨性提高了2倍;650℃回火2 h后,由于基体软化,试样的耐磨性能最差。拉伸测试表明,当回火温度低于550℃时,断口主要以解理断裂为主,550℃回火时抗拉强度最大,为1 928.2 MPa,延伸率为6.4%;当回火温度升高到600~650℃时,断口呈现出韧性断裂,抗拉强度降低,延伸率增大。

H 13 steel was successfully fabricated by laser additive manufacturing technology. The effect of tempering treatment on the microstructure and mechanical properties was studied by optical microscope （OM）, SEM and XRD. Results show that the microstructure of the as produced H 13 steel is mainly composed of martensite, retained austenite and ultra-fine carbides. After tempered treatments, the martensite is converted into tempered martensite and some fine alloyed carbides participated in the matrix. When the tempering temperatures exceed 550 ℃, the carbides becomes coarse. With increasing of tempering temperatures, the microhardness increases firstly and then decreases, which reaches the maximum, 600 HV0.3 after tempered at 550 ℃. The wear mechanism of the samples tempered under different conditions is mainly adhesive wear and mild oxidation wear. When treated at 550 ℃, wear resistance increases twice than that of as-deposited samples. While treated at 650 ℃, wear resistance is the worst due to the soft matrix. Tensile tests show that the main characteristic of the broken pieces is cleavage fracture mode when tempering temperatures below 550 ℃. The largest ultimate tensile strength is 1 928.2 MPa with the elongation of 6.4% after the sample is tempered at 550 ℃. As the temperature ranging from 600 ℃ to 650 ℃, the ductile fracture mode can be observed on the broken pieces, and the tensile strength decreases while elongation increases.