烧结Cr15高铬铸铁组织与性能的研究

为研发耐磨性能优良、成本相对低廉的高铬铸铁,本文分别以亚共晶、过共晶的水雾化Cr15高铬铸铁粉末为原料,采用超固相线液相烧结工艺制备了烧结高铬铸铁(SHCCI),并对其显微组织、力学性能和冲击磨粒磨损工况下的耐磨性能进行对比研究。结果表明,烧结高铬铸铁主要由M7C3碳化物、马氏体和奥氏体组成;在亚共晶烧结高铬铸铁中,通过电解腐蚀萃取的M7C3碳化物三维形貌呈珊瑚状,沿晶界均匀分布,材料抗冲击耐磨性能优良;在过共晶烧结高铬铸铁中,优先形成的初生碳化物可能成为共晶碳化物的生长基底,形成核-壳结构的M7C3碳化物,沿晶界相互连接呈网状,严重割裂基体。亚共晶、过共晶烧结高铬铸铁的力学性能分别为:硬度HRC63.9、HRC64.3,冲击韧性7.92、3.04 J/cm^2,抗弯强度2112.65、1624.87 MPa。

Study on microstructure and mechanical properties of sintered Cr15 high chromium cast iron

To develop high chromium cast iron with excellent wear resistance and relatively low cost, the sintered high chromium cast iron(SHCCI) were fabricated by super-solidus liquid phase sintering technology with hypoeutectic and hypereutectic of water atomized Cr15 high chromium cast iron powders as raw materials, and its microstructure, mechanical properties and wear resistance under impact abrasive wear conditions were compared and analyzed. The results showed that the SHCCI consisted of M₇C₃ carbides, martensite and austenite;the three-dimensional morphology of the M₇C₃ carbides extracted by electrolytic corrosion is coral-like in the hypoeutectic SHCCI, distributed evenly along the grain boundary, and the material has excellent wear resistance. The primary M₇C₃ carbides preferentially produced in hypereutectic SHCCI may act as the substrate structures of the eutectic carbides to form the M₇C₃ carbides with core-shell structure, which are interconnected along the grain boundaries to form a network, severely fractured the matrix. The mechanical properties of the SHCCI with hypoeutectic and hypereutectic are as follows: hardness HRC63.9, HRC64.3, impact toughness 7.92, 3.04 J/cm² (specimens with dimensions of 5 mm×5 mm×50 mm were used), bending strength 2 112.65, 1 624.87 MPa.