High-temperature-resistant niobium-containing vermicular graphite cast iron and preparation method thereof

Abstract

The invention provides high-temperature-resistant niobium-containing vermicular graphite cast iron and a preparation method thereof, and relates to the technical field of vermicular graphite cast iron casting. The method specifically comprises the following steps: taking pig iron, scrap steel and recirculated iron as furnace charges, adding other alloys to smelt into molten iron, and particularly adding a vanadium-iron alloy and a niobium-iron alloy, so that the molten iron contains 0.1-0.4% of V and 0.03-0.07% of Nb; the niobium-containing vermicular graphite cast iron with both high temperature resistance and use performance can be prepared by synergistic interaction with other components in molten iron and optimization and improvement of process parameters. The preparation technology is easy to operate and low in energy consumption, the production process is easy to control, the metallographic structure of the vermicular graphite cast iron prepared through the scheme is mainly ferrite, the pearlite structure is stabilized to be 5% or below, and the high-temperature stability of the matrix structure can be effectively improved. Besides, a sample with the diameter of 10.1 mm, which is prepared from the vermicular graphite cast iron disclosed by the invention, has the maximum tensile strength of 5.5 kN and the maximum tensile strength of 69 MPa at the temperature of 800 DEG C.

Description

technical field [0001] The invention belongs to the technical field of vermicular graphite cast iron casting, in particular to a high-temperature resistant niobium-containing vermicular graphite cast iron, and also provides a preparation method of a high-temperature resistant niobium-containing vermicular graphite cast iron suitable for industrial production. Background technique [0002] The formation process of graphite in cast iron is called graphitization process, and the basic process of formation of cast iron structure is the formation process of graphite in cast iron. The type and size of graphite in gray cast iron depends on the branching and growth rate of graphite in the eutectic group. When the eutectic group stops growing, the growth of graphite also stops. Gray cast iron is widely used in the field of casting technology due to its good casting performance, vibration damping performance, wear resistance, machinability and low notch sensitivity. Vermicular graphi...

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Problems solved by technology

[0003]However, with the continuous improvement of national emission standards and engine power, the thermal-mechanical load on the exhaust pipe is also gradually increasing

Exhaust pipes work under high temperature conditions for a long time, resulting in frequent fatigue failure and fracture, which has a significant impact on vehicle life and driving safety

Therefore, it is difficult for ordinary high temperature resistant vermicular graphite cast iron materials to meet the requirements when used in fields that require high temperature resistance and serviceability of materials, such as materials for preparing automobile turbine casings and exhaust pipes.

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