本研究主要探討鉻鉬複合添加於高矽球墨鑄鐵對其機械性質之影響;試料之碳含量固定為3.2wt%,矽含量固定為4.4wt%,針對不同鉻添加量(0.3wt%、0.6wt%、0.9wt%)及不同鉬添加量(0.5wt%、1.0wt%、1.5wt%),進行金相組織、硬度、拉伸強度、拉伸破斷面、耐氧化性的分析,探討合金元素添加量的不同對於高矽球墨鑄鐵強化的效果。 實驗結果得知,硬度方面以0.9%Cr-1.5%Mo時最佳,BHN為263,鉻添加量在0.9%時,且鉬添加量在0.5%以上,BHN能達到239以上;拉伸方面以0%Cr-0.5%Mo時最佳,為653.1Mpa:拉伸破斷面觀察發現,少量的碳化物能增加裂紋傳播的阻力,使強度上升,但過多的網狀碳化物,將促使裂縫於碳化物及基地交界處成核,大幅降低拉伸強度及伸長率;抗氧化能力方面以0.9%Cr-0%Mo時最佳,其氧化增重率最小,為0.095%。
The research is mainly to discuss the effect of mechanical properties of adding Cr/Mo into high silicon ductile irons. The specimen with 3.2wt% C, and 4.4wt%Si. To be aimed at different adding amount of chromium and molybdenum, they can be proceeded the analyses of metallization, hardness, tensile strength, tensile fracture surface、and the oxidation resistance, and discuss the effect of different adding amount of alloy on the strength of high silicion ductile irons . According to the test results, the best hardness is 0.9%Cr-1.5%Mo, BHN is 263, When Cr:0.9%, Mo>0.5%, BHN can reach above 239. However, the best tensile strength is 653.1 Mpa(0%Cr-0.5%Mo). Observe the tensile fracture surface find that a few carbide could increase the resistance of fracture spread, and increase the strength. The best oxidation resistance is 0.9%Cr-0%Mo and the adding weight rate of oxidation is the lowest, 0.095%.