A kind of austempering ductile iron and its quenching process

Abstract

The invention provides an austempered ductile iron adjusting chemical component. The chemical component uses Mn and Si as a base to substitute Mo and Ni, and contains a plurality of elements comprising Cu, B, Nb and Cr to realize low and micro alloying, so the respective effects of all elements are fully performed, the interactive effect promotion is realized, the hardenability is increased, the alloy consumption is reduced, and the cost is reduced. The invention also provides a new austempered ductile iron quenching technology matched with the austempered ductile iron. The technology is a step austempering technology using step quenching oil and an air isothermal furnace. The heat treatment of a workpiece through the technology realizes crystal grain refinement, good hardenability, high strength and toughness, low hardness (HB190-240) before the step austempering treatment, and good processing performances; and the obtained processed austempered ductile iron has a high hardness (HRC35-56) and extremely less oxidation and deformation, so the precision is guaranteed, and finishing treatments comprising grinding and the like are not needed. Compared with traditional nitrate bath austempering technologies, the austempered ductile iron quenching technology has the advantages of low cost, no generation of large amounts of harmful substances comprising nitrite or the like, low pollution and safety.

Description

technical field [0001] The invention relates to the technical field of heat treatment of metal materials, in particular to an austempering ductile iron and a quenching process thereof. Background technique [0002] Austempered ductile iron (ADI) refers to the cast iron material obtained after a certain composition of nodular cast iron is heat-treated by an austempering process. It has good comprehensive mechanical properties such as high strength, elongation and impact value, especially high bending fatigue strength and wear resistance. Therefore, austempering ductile iron (ADI) is often used to replace nodular cast iron, cast steel, forged steel, and aluminum alloys, and is widely used in transportation vehicles, diesel engines and other internal combustion engines, agricultural and forestry machinery, etc., to manufacture such as crankshafts, connecting rods, gears, Wheel hubs, spring steel plates, cylinder blocks, bushings, universal joints, and other important structura...

AI Technical Summary

Problems solved by technology

[0004] Moreover, in the traditional nitrate salt bath isothermal quenching process, because nitrate will not only produce a large amount of nitrite harmful substances when melting, it will seriously pollute The environment is harmful to human health, and the time for nitrate melting and austempering during the austempering process is long, resulting in low productivity and high production costs

[0005]In addition, traditional nodular cast iron is expensive due to the addition of expensive molybdenum (Mo) and nickel (Ni), which is extremely expensive. The earth has influenced the overall development of the Austempered Ductile Iron (ADI) industry

Moreover, the traditional nodular cast iron is not only weak in hardenability and hardenability, but also prone to adverse phenomena such as element microsegregation, which leads to uneven matrix structure, reduces strength and toughness, and the workpiece is easily damaged and prone to safety failures during use.

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