Full name bearing steel bearing steel, high compressive strength and fatigue limit, high hardness, high wear resistance and a certain toughness, hardenability, good, very strict control of sulfur and phosphorus, is a high-quality steel, can be do cold doing touch with steel. Specific gravity: 7.81

 

(A) bearing steel forging temperature

 

(1) initial forging temperature: 1150 (1120) Final satin Temperature: 850 (800) degrees.

 

(2) removal of surface defects before forging, try to warm up after rapid heating.

 

(3) temperature processing should be avoided 200 to 400 degrees blue brittle zone. Thermal processing, should avoid entering the high temperature brittle zone (greater than 1250). Should try to avoid entering the hot brittle zone (800 to 950 degrees). Today's Focus:

 

(Two) heat treatment after forging

 

(1) Pre-heat treatment after forging ---- (ball annealing) ---- final heat treatment (quenching and tempering)

 

(2) ball annealing Objective: To reduce the hardness, ease of processing, preparing for the quenching.

 

Ball annealing processes: heated to 750 ~ 770 degrees, holding a certain time, slowly cooled to 600 degrees below air cooling.

 

(3) a variety of bearing steel quenching and tempering and hardness

 

Steel quenching and tempering temperature and the quenching medium hardness HRC

 

GCr6 800 ~ 820 150 ~ 170 water or oil 62 ~ 64

 

GCr9 800 ~ 830 150 ~ 170 water or oil 62 ~ 64

 

GCr9SiMn 810 ~ 820 Water or oil 150 ~ 16 062 ~ 64

 

Oil GCr15 820 ~ 846 150 ~ 160 62 ~ 64

 

Oil GCr15SiMn 800 ~ 840 150 ~ 170 62 ~ 64

 

(Three) quenching and quenching medium

 

(1) quenching color (experience) white the most hard and brittle, hard and tough yellow, blue soft and tough.

 

(2) quenching medium

 

A Water: Average temperature does not exceed 40 degrees, do not have oil, soap and other impurities.

 

Salts and alkali solution B: water plus 5 percent salt or base 10.

 

Salt solution cooling rate is ten times that of water, high hardness and uniform, but the organization stress, have some rust effect. Temperature is less than 60 degrees.

 

Alkaline solution (caustic soda solution) corrosive large, to adapt to a small range.

 

C oil: including oil, spindle oil, transformer oil, diesel and so on. Reduces deformation and cracking. NA carbon steel. Oil temperature: 60 to 80 degrees, the maximum does not exceed 100 to 120 degrees.

 

(Four) tempering temperature

 

Bearing steel using low-temperature tempering. Temperature: 150 to 250 degrees. Can maintain high hardness and high wear resistance under the premise of reducing stress and brittleness, when used to prevent premature cracking or damage. Hardness HRC: 58 ~ ~ 64.