通过改变激光粉末床熔融(laser powder bed fusion,LPBF)的扫描速度研究IN738LC合金组织演化及各向异性机制,采用光学显微镜(optical microscopy,OM)及扫描电镜(scanning electron microscopy,SEM)对组织形貌特征进行表征分析,通过X射...通过改变激光粉末床熔融(laser powder bed fusion,LPBF)的扫描速度研究IN738LC合金组织演化及各向异性机制,采用光学显微镜(optical microscopy,OM)及扫描电镜(scanning electron microscopy,SEM)对组织形貌特征进行表征分析,通过X射线衍射(X-ray diffraction,XRD)对其织构性进行测试,使用显微硬度仪对显微硬度及各向异性进行评价.结果表明,随着扫描速度从800 mm/s提高到1600 mm/s,晶粒尺寸得到显著细化,且晶粒长轴取向由低扫描速度下沿建造方向择优,转变为高扫描速度下的沿熔池边界法线方向择优.这是因为低扫描速度下高熔池重熔率导致更多枝晶沿建造方向外延择优生长.这种沿建造方向的强择优生长同时导致(200)面沿建造方向择优的织构性,且这种织构强度随扫描速度增加而降低.这种(200)面沿建造方向择优织构还导致水平截面软轴居多,进而导致水平显微硬度低于侧界面显微硬度的各向异性.展开更多
本文采用激光熔覆技术在Q345钢表面熔覆两种镍基涂层,并分析两种涂层的微观组织、相结构,以及涂层对Q345钢的硬度、耐腐蚀和耐磨损等性能的影响。结果表明,WC增强镍基涂层与Q345钢基体形成良好的冶金结合,表面无明显缺陷;涂层内丰富的...本文采用激光熔覆技术在Q345钢表面熔覆两种镍基涂层,并分析两种涂层的微观组织、相结构,以及涂层对Q345钢的硬度、耐腐蚀和耐磨损等性能的影响。结果表明,WC增强镍基涂层与Q345钢基体形成良好的冶金结合,表面无明显缺陷;涂层内丰富的镍铁金属间化合物Ni3Fe,还有分解的次生碳化物W2C等。这些微观组织、结构使得复合涂层具有更高的显微硬度和更好的耐蚀性能。其中相较于Ni2涂层,Ni1涂层具有更小的腐蚀电流和更大的腐蚀电压,防腐性能好,发生腐蚀的倾向小;同时Ni1涂层也具有更高的硬度和更为优异的耐磨性能。In this paper, two kinds of nickel-based coatings are melted on the surface of Q345 steel by laser cladding technology, and the microstructure and phase structure of the two coatings are analyzed, as well as the effect of the coatings on the hardness, corrosion resistance, and abrasion resistance of Q345 steel and other properties. The results show that the WC-reinforced nickel-based coatings form a good metallurgical bond with the Q345 steel matrix, with no obvious defects on the surface;the coatings are rich in nickel-iron intermetallic compounds Ni3Fe, as well as decomposition of secondary carbides W2C and so on. The microstructure and structure make the composite coating have higher microhardness and better corrosion resistance. Compared with Ni2 coating, Ni1 coating has smaller corrosion current and larger corrosion voltage, good corrosion resistance and small tendency to corrosion;at the same time, Ni1 coating also has higher hardness and more excellent wear resistance.展开更多
文摘通过改变激光粉末床熔融(laser powder bed fusion,LPBF)的扫描速度研究IN738LC合金组织演化及各向异性机制,采用光学显微镜(optical microscopy,OM)及扫描电镜(scanning electron microscopy,SEM)对组织形貌特征进行表征分析,通过X射线衍射(X-ray diffraction,XRD)对其织构性进行测试,使用显微硬度仪对显微硬度及各向异性进行评价.结果表明,随着扫描速度从800 mm/s提高到1600 mm/s,晶粒尺寸得到显著细化,且晶粒长轴取向由低扫描速度下沿建造方向择优,转变为高扫描速度下的沿熔池边界法线方向择优.这是因为低扫描速度下高熔池重熔率导致更多枝晶沿建造方向外延择优生长.这种沿建造方向的强择优生长同时导致(200)面沿建造方向择优的织构性,且这种织构强度随扫描速度增加而降低.这种(200)面沿建造方向择优织构还导致水平截面软轴居多,进而导致水平显微硬度低于侧界面显微硬度的各向异性.
文摘本文采用激光熔覆技术在Q345钢表面熔覆两种镍基涂层,并分析两种涂层的微观组织、相结构,以及涂层对Q345钢的硬度、耐腐蚀和耐磨损等性能的影响。结果表明,WC增强镍基涂层与Q345钢基体形成良好的冶金结合,表面无明显缺陷;涂层内丰富的镍铁金属间化合物Ni3Fe,还有分解的次生碳化物W2C等。这些微观组织、结构使得复合涂层具有更高的显微硬度和更好的耐蚀性能。其中相较于Ni2涂层,Ni1涂层具有更小的腐蚀电流和更大的腐蚀电压,防腐性能好,发生腐蚀的倾向小;同时Ni1涂层也具有更高的硬度和更为优异的耐磨性能。In this paper, two kinds of nickel-based coatings are melted on the surface of Q345 steel by laser cladding technology, and the microstructure and phase structure of the two coatings are analyzed, as well as the effect of the coatings on the hardness, corrosion resistance, and abrasion resistance of Q345 steel and other properties. The results show that the WC-reinforced nickel-based coatings form a good metallurgical bond with the Q345 steel matrix, with no obvious defects on the surface;the coatings are rich in nickel-iron intermetallic compounds Ni3Fe, as well as decomposition of secondary carbides W2C and so on. The microstructure and structure make the composite coating have higher microhardness and better corrosion resistance. Compared with Ni2 coating, Ni1 coating has smaller corrosion current and larger corrosion voltage, good corrosion resistance and small tendency to corrosion;at the same time, Ni1 coating also has higher hardness and more excellent wear resistance.
