Material number G52986: 52100
G52986 is the Unified Numbering System designation for 52100, high-carbon chromium bearing steel specified in ASTM A295.
What G52986 means
UNS numbers (ASTM E527 / SAE J1086) use a letter for the alloy family and five digits: G = AISI/SAE carbon and alloy steels (G41400 = 4140), S = stainless and heat-resisting steels (S30400 = 304), K = miscellaneous steels (K02600 = A36), T = tool steels, N = nickel alloys. The UNS number identifies a composition, not a product form or property level, so G52986 appears in several ASTM specifications (plate, bar, pipe) with different mechanical requirements.
52100 at a glance
AISI 52100 is the world's bearing steel: 1.0 % carbon and 1.5 % chromium, UNS G52986, melted to extreme cleanliness (oxygen ≤ 15 ppm, near-zero large inclusions) because every rolling-element bearing ball, roller and race is made from it or from its identical twins EN 100Cr6, JIS SUJ2, GB GCr15 and GOST ShKh15. After hardening from 840 °C in oil and tempering at 150–180 °C it reaches 60–64 HRC with a fine dispersion of chromium carbides that gives outstanding rolling-contact fatigue life and wear resistance, plus dimensional stability from the low retained-austenite content that the chromium addition and a cold treatment ensure.
Outside bearings, 52100 is a favourite of knifemakers and blacksmiths (very fine grain, keen edge, forgiving of forging), and it is used for rollers, cams, bushings, gauges, punches, needle valves and any small part that must be hard, precise and wear-resistant. Its hardenability is moderate — sections above about 20–30 mm need the Mn-Si variant 100CrMnSi6-4 (SUJ3) — and, with no ductility to speak of at 62 HRC, it must be machined in the spheroidized state and ground after hardening. Corrosion resistance is nil; stainless bearings use 440C.
Full data sheet for 52100 → · Equivalent grades →