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Cr-Mn-Ti gear steel and preparation thereof

A technology of gear steel and production method, which is applied in the field of metallurgy, can solve problems such as failure, initiation of fatigue crack workpiece, difficulty in pouring molten steel, etc., and achieve the effects of reducing inclusions, improving steel quality, and increasing fatigue life

Inactive Publication Date: 2008-10-01
SHANDONG IRON & STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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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

Method used

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  • Cr-Mn-Ti gear steel and preparation thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] Embodiment 1: the production of novel Cr-Mn-Ti gear steel;

[0025] 1) Primary smelting: The primary smelting furnace melts the primary molten steel, and the primary smelting furnace adopts an electric furnace or a converter; the temperature of the primary smelting furnace is controlled at 1620-1670°C; the steel is tapped within the range of 1600°C-1650°C and synthetic slag is added ;

[0026] 2) LF refining: Refining the molten steel in the ladle refining furnace, reducing the content of [O], [S], and inclusions in the molten steel, and controlling [O]≤15PPm, [S]≤0.030%, and inclusions≤3.0; The temperature is controlled at 1520°C to 1620°C, and the smelting time is 30 to 50 minutes for tapping;

[0027] 3) Treatment of molten steel in a vacuum furnace: Vacuum treatment of molten steel in a vacuum furnace, the vacuum degree is less than 140Pa, the vacuum time is 15-30min, and argon gas is blown into the bottom of the ladle;

[0028] 4) Full-protection continuous casti...

Embodiment 2

[0035] Example 2: Physical properties of steel

[0036]The physical properties of the gear steel of Example 1 were examined. The hardenability and mechanical properties of Cr-Mn-Ti gear steel were determined according to the GB / T225 method, and the high-magnification inspection of Cr-Mn-Ti gear steel was carried out according to the GB / T 13299 method; the measurement results are shown in Table 3.

[0037] Table 3 Physical properties of steel

[0038]

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Abstract

The invention provides a production method for a novel Cr-Mn-Ti gear steel, characterized in that the invention uses the production process flow of initial refining with an electric furnace or a rotary furnace, LF refining, treatment for refined steel liquid with a vacuum furnace, fully-protective continuous casting and rolling formation. An initial-refining furnace melts the initial-refining steel liquid, forms steel in the range from 1620 to 1670 DEG C and adds synthesized dregs; the refining of the steel liquid is performed in a steel container refining furnace and the temperature is controlled in the range from 1520 to 1630 DEG C, the steel is made after refining for 30 to 50 minutes; then the refined steel liquid is vacuum performed on the vacuum furnace, argon gas is blown into the bottom of the steel container; in the end, the continuous casting is carried out under the condition of full protection. The invention, in terms of guaranteeing the intensity of the CrMnTi gear steel and considering the fatigue limit, controls the Ti content in the CrMnTi gear in the range from 0.01% to 0.038%, which can not only control the CrMnTi gear steel not to enlarge the grain at the carburizing temperature to reduce the impurities, thus improving the steel quality, but also is beneficial to improving the fatigue life of the gear.

Description

technical field [0001] The invention belongs to the technical field of metallurgy and belongs to the alloy steel category. It relates to a novel Cr-Mn-Ti 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 Ti ...

Claims

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Application Information

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IPC IPC(8): C22C38/28C22C33/04B21B37/74
Inventor 董杰吉雍歧龙杜显彬张利平翟正龙孙新军李艳青范黎明郑艳
Owner SHANDONG IRON & STEEL CO LTD
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