Preparation of Cr-Mn-Ti gear steel

Abstract

The invention provides a production method of Cr-Mn-Ti gear steel, which is characterized in that it adopts the production process of primary smelting in electric furnace or converter—LF refining—vacuum furnace for refining molten steel—full protection continuous casting—rolling into lumber ; The primary smelting furnace melts the primary molten steel, taps steel in the range of 1620°C to 1670°C and adds synthetic slag; carries out refining of molten steel in the ladle refining furnace, controls the temperature at 1520°C to 1630°C, and smelting time at 30 ~50min to tap the steel; then carry out vacuum treatment on the refined molten steel on the vacuum furnace, and blow argon gas into the bottom of the ladle; finally carry out continuous casting under the full protection state. From the perspective of ensuring the strength and fatigue limit of the CrMnTi gear steel, the present invention controls the Ti content in the CrMnTi gear steel to 0.01% to 0.038%, so as to control the grain growth of the CrMnTi gear steel at the carburizing temperature. , Reduce inclusions, improve the purpose of steel, and at the same time help to improve the fatigue life of gears.

Description

technical field [0001] The invention belongs to the technical field of metallurgy and belongs to the alloy steel category. The invention relates to a CrMnTi gear steel for manufacturing gears. Background technique [0002] As a traditional old product of gear steel in my country, CrMnTi gear steel was recommended by the former Soviet Union in the 1950s. The grains are refined by Ti element, and the domestic production process in metallurgy, gear processing and heat treatment is mature and stable. CrMnTi gear steel is very easy to form titanium inclusions. Due to the high viscosity of the steel, it is difficult for TiN to float up when the steel ingot is solidified, so it often exists in the steel in the form of inclusions; TiN with coarse particles will cause the ingot to be in forging. Longitudinal cracks occur during the process, which can easily cause quenching cracks during subsequent processing and use, reducing the fatigue life of the steel; at the same time, adding T...

AI Technical Summary

Problems solved by technology

[0009] Due to the existence of excess Ti, it is difficult to pour molten steel, and the surface defects of the steel ingot increase. The large-grained TiN inclusions formed in the liquid state cause small pits in the gear during use, or at its corners or between it and Initiation of fatigue cracks at the interface of the matrix promotes premature failure of the workpiece

Images