Production method of spheroidal graphite cast iron for hydraulic parts and prepared spheroidal graphite cast iron

Abstract

The invention relates to a production method of spheroidal graphite cast iron for hydraulic parts and prepared spheroidal graphite cast iron. The production method comprises the following steps of a material proportioning procedure, a charging melting procedure and a nodulizing inoculation procedure. In the material proportioning process of the material proportioning procedure, the adopted raw materials by weight part comprise 25-35 parts of pig iron for steelmaking, 33-43 parts of steel scrap, 26.5-36.5 parts of scrap return, 0.3-0.5 part of red copper and 0.5-2.5 parts of carburizing agent.A completely new formula is adopted. As a defined amount of red copper is added in ferritic nodular iron, a matrix structure can be added with 20-40 percent of pearlite content, the hardness can be increased by 8-10 percent, the tensile strength can be increased by 9-11 percent, the yield strength can be increased by 8-10 percent, and the elongation can be reduced by 20-30 percent. The too-soft defect of the ferritic nodular iron in the machining process can be obviously overcome, and the machining performance is increased.

Description

technical field [0001] The invention relates to nodular cast iron, in particular to a production method of nodular cast iron for hydraulic parts and the prepared nodular cast iron. Background technique [0002] Ductile iron is a gray cast iron with excellent mechanical properties. Generally, before pouring, add a small amount of spheroidizer (usually magnesium, rare earth magnesium alloy or cerium-containing rare earth alloy) and inoculant (usually ferrosilicon) to molten iron to obtain spherical graphite through spheroidization and inoculation treatment, with Strong anti-oxidation growth, corrosion resistance and machinability, but the linear shrinkage rate and thermal cracking tendency are small, especially the plasticity and toughness are improved, so that the strength is higher than that of carbon steel, and its comprehensive performance is close to that of steel , which effectively improves the mechanical properties of cast iron. Based on its excellent performance, it ...

AI Technical Summary

Problems solved by technology

The supporting hydraulic parts of the 8.5-ton hydraulic excavator are mainly PA10VO71DFLR axial plunger variable pump, V8SX14 hydraulic valve, and MA10FD45 hydraulic motor. The parts made of QT-450 include: oil inlet valve body, boom valve body , Tail valve body, intermediate valve body, back cover, housing, pump body, cylinder block, swash plate, control valve body, valve body, swash plate, so when these components are made of ductile iron, today’s The hardness, tensile strength, yield strength and elongation of ductile iron are not ideal, and the ferritic ductile iron is too soft during processing, so different formulas should be adopted in the production method of ductile iron to solve this problem. question