Production method of cast state high extension rate ductile iron

Abstract

A method to produce as-cast spheroidal graphite iron with high elongation percentage is disclosed, which belongs to the field of casting technique. Steps of the method are as follows: One of foundry pigs such as Z18 or Z22 is taken as material. Based on weight proportion, there are 35-95% pig iron of Z18 or Z22, returns<55%, scrap steel <12% and 0.6-2.5% ferro-silicon. Prepared materials are melted in furnace and nodularized by shocking, in which the addition of nodularizer is 1.4-1.8% of weight of melted iron. Nodularizer is covered and compacted with 75 size ferro-silicon which is 0.3-0.5% of melted iron. The 75 size ferro-silicon is inoculated again before discharging melted iron to nodularize. Weight proportion of chemical constitution of nodularized melted iron is C3.5-4 %,Si2.6-3.2%,Mn0.15-0.5%,P<=0.06%,S<=0.03%. Nucleating agent is used for instantaneous inoculation when extending cast, which can get as-cast spheroidal graphite iron with high elongation percentage. The method can lower cost, shorten production cycle of casts and extend preferred range of materials. Casts are not tend to get shrinkage voids. None or small quantity of ferro-silicon alloy is added in furnace rear, which can save cost.

Description

Technical field [0001] The invention relates to a production method of as-cast high elongation nodular cast iron, which belongs to the technical field of casting. Background technique [0002] In the field of casting, ductile iron with an elongation greater than 10% is called high elongation ductile iron. This ductile iron is widely used in the machinery industry and automobile manufacturing industry. [0003] The general production method of high elongation ductile iron is to use the chemical composition of carbon (C) 3.5-4%, silicon (Si) 2.0-2.5%, manganese (Mn) 0.2-0.6%, phosphorus (P) ≤ 0.06%, Sulfur (S) ≤ 0.03% as-cast ductile iron, which is annealed at a medium and high temperature above 800-950℃ to meet the elongation requirement of more than 10%. [0004] The following three deficiencies in the above-mentioned high elongation ductile cast iron production methods are increasingly recognized and valued by the industry. One is that high temperature annealing will bring energ...

AI Technical Summary

Problems solved by technology

However, there are some deficiencies in the new iron for ductile iron (Q10-Q16). First of all, the price of new iron for ductile iron is higher than that of cast new iron, generally about 10 yuan (RMB) higher per ton, which will cause ductile iron Increase in production cost; secondly, when producing ductile iron with a relatively high silicon content (Si>2.6%), since the new iron for ductile iron (Q10-Q16) has a low silicon content, it is necessary to add ferrosilicon after the furnace To ensure the silicon content of molten iron, it also increases the cost