52100, GCr15 and 100Cr6 — interchangeable?

For most bearing and wear applications yes: carbon and chromium windows overlap closely. Certified bearing production still orders to the named standard because inclusion and spheroidization ratings differ in detail.

Why is 52100 supplied annealed so soft?

Spheroidizing converts carbides to globules in a soft ferrite matrix, giving the machinability needed to turn bearing blanks before the final hardening to 62–66 HRC.

Grades · Alloy & Engineering Steel · 52100

52100

Data verified

52100 is the world-standard through-hardening bearing steel (ASTM A295): about 1% carbon and 1.5% chromium, hardened to 62–66 HRC for rolling contact fatigue resistance. The JIS name is SUJ2 and the EN name 100Cr6 — all describe the same grade family.

Hardness62–66 HRC

DIN1.3505 (100Cr6)

AISI52100

JISSUJ2

CategoryAlloy & Engineering Steel

Chemical composition

Element	Content (%)
C	0.98–1.10
Si	0.15–0.35
Mn	0.25–0.45
P	≤0.025
S	≤0.025
Cr	1.30–1.60

Weight percent, per the governing standard ranges. Actual values per heat are on the mill certificate.

Properties

Delivery condition	Spheroidize annealed (≈180–210 HB)
Hardness (hardened)	62–66 HRC
Density	7.85 g/cm³

Heat treatment

Spheroidize anneal 760–790 °C; harden 830–860 °C oil; temper 150–180 °C for 62+ HRC bearing duty.

Equivalent grades

Standard	Designation
din	1.3505 (100Cr6)
aisi	52100
jis	SUJ2
gb	GCr15

Compare side by side: 52100 vs GCr15 · 52100 vs 100Cr6 · 52100 vs 5195

Equivalents overlap in chemistry and use but are not always identical — see our equivalents guide before substituting in certified designs.

Applications & Processing

Applications: Ball and roller bearings, races, precision shafts, gauges, high-wear machine parts.

Processing: Supplied spheroidize annealed for machinability; cleanliness (inclusion rating) is the critical purchase spec for bearing life.

FAQ

52100, GCr15 and 100Cr6 — interchangeable?: For most bearing and wear applications yes: carbon and chromium windows overlap closely. Certified bearing production still orders to the named standard because inclusion and spheroidization ratings differ in detail.
Why is 52100 supplied annealed so soft?: Spheroidizing converts carbides to globules in a soft ferrite matrix, giving the machinability needed to turn bearing blanks before the final hardening to 62–66 HRC.

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Source: ASTM A295 published ranges · Last updated 2026-11-03. Data is indicative — verify critical values against the governing standard and mill certificate before use.