Method for modifying carbides in austenitic heat-resistant steel

Abstract

The invention discloses a method for modifying carbides of austenitic heat-resistant steel. The method comprises sequentially smelting magnesium-containing austenitic heat-resistant steel raw materials through an electric furnace, AOD furnace smelting, LF furnace refining, and feeding Nickel-magnesium cored wire, continuous casting or die casting, blooming or die casting, rolling, total solution and aging solution to obtain the modified austenitic heat-resistant steel; wherein, refining in the LF furnace The nickel-magnesium cored wire is fed at the end, and the nickel-magnesium cored wire includes the following components by mass percentage: Mg 7-25%, Ni 5-45%, Cr 20-40%, N0.1-5.5%, and the balance For Fe and inevitable impurity elements. The method for modifying the austenitic heat-resistant steel of the present invention has stable wire feeding process, gentle reaction, no violent splashing, high yield of magnesium element, reaching 20%-35%, and low production cost.

Description

technical field [0001] The invention relates to the technical field of iron and steel metallurgy, in particular to a method for modifying carbides of austenitic heat-resistant steel. Background technique [0002] Austenitic heat-resistant steel is widely used in metallurgy, mining, petrochemical, electric power and other industrial production, used to prepare such as CDQ coke oven lining, thermal power plant boiler burner nozzle, circulating fluidized bed boiler air cap, cyclone Heat-resistant components such as tube-in-tube hanging pieces. High-temperature stability and high-temperature strength are the two major performance indicators of heat-resistant steel, and they are also important research topics for heat-resistant steel in engineering applications. [0003] 21-4N steel is a typical heat-resistant steel as exhaust valve steel commonly used at home and abroad, also known as valve steel. Its composition is: C 0.48-0.58%, Si<0.35%, Mn 8.00-10.00%, P<0.04%, S<...

AI Technical Summary

Problems solved by technology

Ribbon carbides and network carbides are essentially carbides precipitated from austenite, so they are also collectively referred to as secondary carbides. The existence of secondary carbides weakens the bonding force between metals, making the steel The mechanical properties are reduced, especially the impact toughness is reduced, and it is easy to cause grain boundary cracking and reduce the wear resistance of steel

[0006] In order to improve the distribution of carbides in the steel, reduce the proportion of carbides, especially the proportion of reticular carbides, and improve the performance of austenitic valve steel, rare earth and other elements can be added to the steel to form carbides. regulation, but the cost of rare earth is high, the detection is complicated, and the pouring process is easy to accumulate tumors at the nozzle

[0007] Since the melting point of magnesium is 649°C, the boiling point is 1090°C, and the vapor pressure is 2.038MPa at 1600°C, that is, the vapor pressure is more than 20 atmospheres, the boiling point of magnesium is relatively low, so magnesium cored wire is added during the process of adding molten steel. During the process, it will volatilize and lead to low yield; on the other hand, when the oxygen level of molten steel is high, deoxidation reaction will occur when feeding magnesium cored wire, which will also cause a significant decrease in yield, severe splashing and violent reaction during the process The problem

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