100Cr6 is a special steel for German standard bearings, which adds a certain amount of chromium (Cr) compared with carbon tool steel, which makes its hardenability, hardness and wear resistance significantly improved. The contact fatigue strength of this steel is also very high, which does not change much in size under quenching and tempering conditions.
The hardenability of this type of steel is significantly improved due to the addition of alloying elements, which means that the use of oil cooling instead of water cooling can reduce the stress during die quenching, thereby reducing the risk of deformation and cracking. In the tempering process, martensite is not easy to decompose, and the decomposed carbides are also difficult to accumulate and grow, so the tempering resistance of the tool and die is improved. The tool and die after low temperature tempering have higher strength and better wear resistance, which makes its service life can be greatly improved.
In practical applications, 100Cr6 bearing steel is often used to make molds such as wire drawing dies and cold heading dies.
The 100Cr6 steel implements the DIN 17350 standard and the chemical composition is as follows:
Carbon (c): 095-1.10%
Silicon (Si): 010-0.35%
Manganese (mn): 020-0.40%
Chromium (cr): 135-1.60%
Phosphorus (p): 0030%
Sulfur (s): 030%
Preparatory heat treatment of 100Cr6 bearing steel.
1) Isothermal annealing after forging: slowly heat to 770 790, keep warm for 1 2h, cool the furnace to 680 700, keep warm for 3 4h and then cool the furnace to below 550 for air cooling, hardness is 187 229hbs.
2) High temperature tempering: heating temperature is 600 700, heat preservation 2 3h, furnace cooling or air cooling, hardness is 187 229hbs. It is mainly used to relieve the stress of cutting before quenching.
3) Normalizing: heating temperature is 930 950, air cooling, hardness is 302-388hbs. It is used to refine the grain of superheated steel and eliminate reticulated carbides.
4) Quenching and tempering treatment: quenching temperature is 840 860, oil cooling;The tempering temperature is 660 680 °C, furnace cooled or air cooled, and the hardness is 197 217 HBS.
Quenching and tempering of 100Cr6 steel.
1) Quenching: heating temperature is 830 850, oil cooling, hardness is 62 65hrc.
2) Tempering: The heating temperature is 150-190, and the hardness is 58-62HRC.
3) Isothermal quenching: the heating temperature is 830 850, 240-300 isothermal quenching. The tempering temperature is 180 200 and the hardness is 58 62hrc.
4) Carbide ultra-fine treatment: the solution temperature is 1050, and the isothermal treatment is carried out in the isothermal bath of 300 350 quenched to obtain the lower bainite structure. The tempering temperature is about 720 and the tempering time is 2h, but the hardness is high and the processing is difficult. It can be changed to a short-time isothermal spheroidization process, 720 heating for 1h, then heating to 780 for 1h, then cooling to 720 and then holding for 1h, and finally the furnace is cooled to 500. After solution isothermal spheroidization, ultra-fine spherical carbides can be obtained.