微合金化对汽车发动机缸体材料性能影响的试验研究

Influence of Microalloying on Material Property of Automobile Engine Cylinder Block

以生铁、硅铁、废钢以及增碳剂等为主要原料,以Mo、Ni、V以及Nb作为合金化元素制备了汽车发动机缸体用铸铁材料,采用砂型铸造并进一步进行热处理获得样品,对其进行力学及耐磨性试验。试验结果显示:当Mo和Nb添加量为0.16%,Ni添加量为0.3%时,各项性能较优,能够获得较好的综合性能,此时铸铁材料样品的抗拉强度为315.6 MPa,显微硬度为223 HB,冲击功为7.6 J/cm^(2),磨损60 min后磨损量为0.089 g,热疲劳寿命为985次。合金元素的加入可以使铸铁内部珠光体组织片间距减小,同时可以细化石墨,形成细小的石墨团,部分合金元素可在基体中产生固溶强化作用。

The material of cast iron for automobile engine cylinder block was prepared with the main raw materials of pig iron, silicon iron, scrap steel and carburizing agent and the alloying element of Mo, Ni, V and Nb. The samples are obtained by sand casting and heat treatment, and then mechanical and wear resistance tests are conducted. The experimental results show that a good comprehensive performance can be achieved with 0.16% addition of Mo and Nb and 0.3% addition of Ni. Accordingly, the tensile strength of prepared cast iron sample is 315.6 MPa, the microhardness is 223 HB, the impact work is 7.6 J/cm^(2), the 60 min-wearing abrasion is 0.089 g, and the thermal fatigue life is 985 cycles. The addition of alloying element reduces the gap of pearlite tissue slice spacing in cast iron, and refines the graphite and forms a fine graphite group. In addition, some alloying elements can produce solid solution strengthening effect in the matrix.