100Cr6 Bearing Steel Roller Vacuum Oil Quenching And Heat Treatment

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100Cr6 bearing steel roller is the most widely used high carbon chromium bearing steel with low alloy content and good performance.After heat treatment, it has high and uniform hardness, good wear resistance and high contact fatigue performance.

100Cr6 bearing steel roller, good toughness, good tempering stability, small deformation during heat treatment.The carbide distribution in the steel is uniform, it is not easy to separate out the carbide net, and it is easy to eliminate by annealing.But the compressive strength and wear resistance is insufficient, the processing is poor.When the residual carbon content on the surface of the steel is 0.6-0.7% decarburization layer, the surface layer’s overheating sensitivity increases due to the reduction of carbide.After normal heating and quenching, the surface hardness can still reach 60-62HRC, but its bending strength decreases by 40-50%.The grain size of the surface layer reaches grade 7 and the core is grade 10.

The steel has good forging performance and needs to be heated in a neutral or protective atmosphere furnace because it is easy to decarburize.The fine tempered sostenite structure can be obtained by applying forging heat conditioning treatment, which can simplify the process, save time and electricity, have good cutting performance and ideal waste heat treatment structure.

(1) Pre-heat treatment
A. Normalizing: Chromium bearing steel normalizing process, the workpiece after diathermy insulation 40~60min, cooling needs to be fast, immediately after normalizing to spherical annealing.

B. Spherification annealing: 100Cr6 chromium bearing steel roller is often used isothermal spherification annealing process, 790℃ is considered to be the best spherification heating temperature.Before annealing, heating to 900~920℃, holding 2/3~1h after normalizing.

The holding time depends on the size of the workpiece, the uniformity of the heating furnace, the loading method and quantity of the furnace, and the uniformity of the original structure before annealing.

Low temperature spheroidizing annealing is mainly used for recrystallization annealing of cold blanking ball and cold extrusion ring.

Ordinary spheroidizing annealing and isothermal spheroidizing annealing are mainly applied to annealing of forged ring, hot stamping ball and transverse forging ball. Spherification annealing process of chromium bearing.

100Cr6 Bearing Steel Roller Heat Treatment

(2) Final heat treatment
A. Bearing parts: generally adopt quenching and low temperature tempering, its purpose is to improve the strength, hardness, wear resistance and fatigue resistance of steel.The quenching temperature of 100Cr6 steel is 820~860℃, and the critical diameter of oil quenching is 25mm.Generally adopt oil cold quenching.The heating and holding time is longer than that of alloy tool steel, and the salt bath heating coefficient is 0.8~1.5min/mm.The heating coefficient of air furnace is 1.5~2min/mm.

160℃±10℃ low temperature tempering, tempering time is generally 2~4h.
Precision bearing parts are of stable size. After quenching, they should be cold-treated at -60~80℃, and the insulation time is 2~4h. After cold-treated, the parts should be returned to room temperature, and tempered within 4h to prevent parts from cracking.

Residual stress which cannot be completely eliminated during low temperature tempering will be redistributed after grinding.These two stresses can lead to changes in the size of parts and even cracks.For this purpose, should be a supplementary tempering, tempering temperature of 120~160℃, insulation 5~10h or longer.

B.The die 100Cr6 heat treatment: because this steel is prone to white spot defects, the heat treatment of large mold is prone to cracking, using slow heating or 690℃ for a long time (more than 5h) section isothermal can reduce the cracking probability, the austenitizing temperature to choose 810℃±10℃, insulation coefficient a=1.6~0.9min/mm.The workpiece with a diameter of more than 60mm shall be quenched with water and oil.

Usage:
It is recommended to make various bearing rings with wall thickness ≤12mm and outer diameter ≤250mm, steel ball diameter ≤50mm, cone and spherical roller diameter ≤22mm and roller needles of all sizes.Also can be used to manufacture measuring tools, molds, woodworking tools.Make internal combustion engines.Steel balls, rollers and bushing on the transmission shafts of electric locomotives, machine tools, tractors, steel rolling equipment, drilling machines, railway vehicles and mining machinery.

Edited by : Frank Lee
Copyright : SIMUWU Vacuum Furnace

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