High-performance as-cast austenite-bainite ductile iron and production method and application thereof

Abstract

The invention provides high-performance as-cast austenite-bainite ductile iron and a production method and application thereof. On the basis of ductile cast iron shell mold casting, the adding quantity ranges of bainite forming elements of Mo, Ni and Cu are defined according to the casting size and unshelling time, and through fine control over the deshelling time and the cooling and heat preservation processes, the production method suitable for the as-cast austenite-bainite ductile iron with complex shape characteristics is finally determined. The as-cast austenite-bainite ductile iron obtained through the method has excellent comprehensive mechanical properties, the tensile strength exceeds 900 MPa, the yield strength is not lower than 600 MPa, the elongation is larger than 4%, and theimpact toughness is larger than 65 J/cm<2>. The Brinell hardness of the austenite-bainite ductile iron obtained in the as-cast state is 250-310 HBS and meets the requirement of machining. The as-castaustenite-bainite ductile iron prepared through the method can be used for various metal components which bear large loads and have high safety coefficient requirements, and is particularly suitable for high-performance engine crankshafts.

Description

technical field [0001] The invention belongs to the technical field of metal material preparation, and particularly relates to a high-performance as-cast austempered ductile iron and a production method and application thereof. Background technique [0002] Austempered ductile iron was originally obtained from ductile iron under austempering conditions, so it is also called austempered ductile iron (ADI). It is a high-grade cast iron with a wide range of mechanical properties, high strength, high toughness and Better plasticity is its main feature. However, in the preparation process, there are still large heat treatment energy consumption, high cost, and NaNO in the isothermal quenching process. 2 and KNO 3 Molten salt will decompose, gasify, produce harmful substances, pollute the environment, endanger health and many other problems. [0003] Based on the above reasons, it has been difficult to obtain large-scale production and commercial application of austenitic ducti...

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Problems solved by technology

[0006] However, a higher alloy composition is bound to greatly increase the cost of the alloy, which is not conducive to the application of as-cast Aubician ductile iron. Therefore, controlling the cooling conditions of castings through various methods can improve the ability to form Aubician structures, and ensure the mechanical properties of castings. Under the premise of reducing the amount of alloying elements added is an important development direction of as-cast Aubian ductile iron

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