Advantages and disadvantages of high Si nodular cast iron

1. Advantages

Referring to the Research Report of zhangboming et al. And in combination with the analysis and research of the project team of the author’s company, the all ferrite matrix nodular cast iron alloyed with Si has the following advantages compared with the traditional ferrite (pearlite) mixed matrix nodular cast iron alloyed with Cu, Sn, etc.

(1) High Si nodular cast iron has high tensile strength, yield strength and elongation, so that most thick wall castings can reduce the wall thickness, so as to reduce the weight of nodular cast iron and save production costs.

(2) The distribution of hardness and tensile strength in the body of high Si ductile iron is uniform.

(3) The ferrite matrix of high Si nodular cast iron is basically more than 95%, the hardness range of nodular cast iron is narrow, the cutting performance is good, the tool life is long, and the machining cost is reduced.

(4) As the shrinkage rate of molten iron is the same as that of other materials with the same tensile strength, the shape of high Si ductile cast iron castings does not need any change. However, due to the improvement of toughness, the design of inner sprue and riser neck must be properly modified to avoid damaging the ductile cast iron when knocking the pouring system, resulting in the lack of meat of the ductile cast iron.

(5) Due to the high Si content in the molten iron of this material, the content of stable pearlite elements and carbide forming elements in the chemical composition can be relaxed, so that a large amount of scrap can be safely used and the production cost can be reduced.

2. Disadvantages

(1) The controllable range of qt600-10 production is very small, that is, the Si content should be strictly controlled below 4.3%.

(2) Due to the high Si content of this material, so far, the surface of nodular cast iron cannot be heat treated, such as quenching.

(3) Poor weld repair performance.