Study On The Microstructure And Mechanical Properties Of Cu/Sb Modified Nodular Cast Iron

Die is one of the most important equipments in automobile industry,and thus it remarkably affects the quality,productivity and cost of products.With the development of the automobile industry,the need of large and medium die increases obviously.Under the satisfaction of the operating requirements,how to increase productivity and reduce costs has became the most significant subject.At present,Nodular Cast Iron(NCI) is employed widely to produce the large and medium die in Japan and some other developed country in the world.However,most NCI die was needed to import from the developed countries to our country.The main reason is that the manufacturing technology and materials are relatively backward in contrast to some developed countries.In the past,most large and medium die were made of alloyed steel,but the high price,complex procedure,long manufacturing cycle,long price and low accuracy were main flaws.Consequently,developing high performance and well mechanical properties NCI for die is of remarkable significance.In this paper,alloying method was adopted to develop new species of NCI which own high performance and good wear resistance,simultaneously the effect of alloying elements on the microstructure and performance of NCI was also systemically studied.Results from observing the microstructure of NCI revealed that alloying elements Cu and Sb could effectively promote the amount of graphite nodule and simultaneously increase the quantity of the pearlite.With the increasing of Sb,the quantity of the pearlite increased significantly.The addition of Cu mixed with Sb could effectively decrease the space of the pearlite and at the same time cut short the dimension of the graphite nodule,the quantity of the pearlite can be almost up to 97% when the amount of alloying elements are Cu:0.5%wt,Sb:0.02%wt.It could almost not find intact ferrite around the graphite nodule.Mechanical performance test indicates that alloying elements Cu and Sb could remarkably promote the strength and hardness of NCI.NCI owns the best mechanical performance when the quantity of the alloying elements are Cu:0.5 wt%,Sb:0.02 wt %.Results from wear test suggest that the alloying modified NCI performed better than common NCI.In a word,the Cu,Sb modified NCI performs better than common NCI in mechanical properties and wear resistance,and therefore the Cu,Sb modified NCI could be employed for the replacement of alloying steel in producing the large and medium die in automobile industry.