GCr18Mo Ball Bearing Steel Bar

GB/T 18254 GCr18Mo is a kind of high-carbon chromium bearing steel, also a new high abrasive resistance steel. GCr18Mo is equivalent to SKF24 at Swedish standard. Compared with GCr15 and GCr15SiMn, GCr18Mo has more percent of Cr element which improves the abrasive resistance and is added Mo element.

GCr18Mo is mainly used to manufacture various bearing inner rings (wall thickness up to 20mm, not the 16mm, making a wide use. Except that, GCr18Mo can also be used to manufacture internal-combustion engine, electric locomotive, machine tool, tractor, steel rolling equipment, driller, steel balls, roller, and axle sleeve of rail truck, mining machine spare.

When the rolling bearing is in operation, there is point or line contact between the ring and the rolling element. The contact stress is usually 1470~4900MPa, and the number of stress changes per point (or line) varies from thousands to tens of thousands of times per minute. In addition to high-speed rotation, the bearing is also subject to sliding friction and a large impact load during operation. Therefore, the chemical composition of the bearing steel must meet the following requirements:

1.  High fatigue limit;
2. High elasticity and hardness;
3. High wear resistance;
4. High strength and high impact toughness.

The steel used to manufacture bearings must have high metallurgical quality. That is, the annealed structure should be uniform granular pearlite; the quenched and tempered structure should have:

1. Cryptocrystalline or fine crystalline martensite;
2. High toughness lower bainite and bainite and martensite composite structure.

In order to obtain the lower bainite structure, especially for bearings with large wall thickness subjected to impact load, the hardenability of the old standard GCr15SiMn steel is only J60/50 which cannot meet the requirements. Therefore, a new steel grade GCr18Mo was developed. And use the following chemical composition:

C 0.95%~1.05%,

Si 0.25%~0.45%,

Mn 0.30%~ 0.50%,

Cr 1.70%~1.95%,

Mo 0.15%— 0.30%,

S< 0. 020%,

P< 0. 027%,

The newly developed GCr18Mo bearing steel has solved the defects of GCr15SiMn bearing steel. GCr18Mo bearing steel has high fatigue limit, high elasticity and hardness, high wear resistance, high toughness and impact toughness.

Chemical Composition:

Mechanical Properties: