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Steel 100CrMo7-4 +AC+C

Supply condition

EN 100CrMo7-4

+AC+C = spheroidize annealed and cold drawn bar

Choose for close-tolerance bright bar (rollers, pins, small rings) where the drawn surface and size accuracy save a turning operation.

Standard cost $$
Request a quote in 100CrMo7-4 +AC+C100CrMo7-4 overview

Values for the +AC+C condition

Other 100CrMo7-4 tempers and conditions

100CrMo7-4 is listed in 7 conditions; see the grade overview at 100CrMo7-4.

Compare all 7 conditionsHide
Condition · open for datasheetBest forYield MPaTensile MPaElong. %HardnessConductivity
+ACDefault
Spheroidize annealed
Standard stock condition for bearing-ring blanks: soft, globular carbide structure giving the best machinability and cold-forming behaviour before hardening.41068020207 HB44 W/m·K
+A
Annealed
General soft-annealed delivery condition when a full spheroidized carbide structure is not contractually required.4207001817 HRC6.6 % IACS
HR
Hot rolled
Mill-supplied as-rolled bar for re-heating/forging; hardness too high and structure too banded for direct machining.5609501030 HRC6.4 % IACS
+AC+CThis page
Spheroidize annealed and cold drawn bar
Choose for close-tolerance bright bar (rollers, pins, small rings) where the drawn surface and size accuracy save a turning operation.62078011235 HB—
+B
Bainite hardened
Austempered lower-bainite condition for heavy-section, shock- or contamination-loaded bearings: compressive surface stresses, better toughness and crack resistance than martensite.1,6502,0001.560 HRC—
+QT58
+QT 58–61 HRC
Higher-temper condition for rings that must stay dimensionally stable at elevated running temperature (up to ~180 °C) at slight hardness cost.1,7502,050160 HRC36 W/m·K
+QT62
+QT 61–64 HRC
Standard finished-bearing condition: maximum hardness and rolling-contact fatigue life for raceways and rolling elements up to ~150 °C.1,9502,2500.762 HRC34 W/m·K

What is 100CrMo7-4 +AC+C?

100CrMo7-4 +AC+C is 100CrMo7-4 supplied in the +AC+C condition — choose for close-tolerance bright bar (rollers, pins, small rings) where the drawn surface and size accuracy save a turning operation. 100CrMo7-4 +AC+C has a yield strength of 620 MPa (89.9 ksi) and a tensile strength of 780 MPa (113 ksi) — stronger than 78% of steel grades. Elongation at break is 11% and the elastic modulus is 210 GPa (30.5 Msi). 100CrMo7-4 +AC+C has a density of 7.83 g/cm³ (0.283 lb/in³), lighter than 80% of steel grades. It melts at 1,420°C (2,588 °F). +AC is the default condition FabDigit quotes; +AC+C is available on request or by drawing note.

Advantages

  • Polishes to a fine finish — 85/100, better than 99% of steel grades
  • High strength — 620 MPa (89.9 ksi), better than 78% of steel grades

Limitations

  • Difficult to weld — 12/100, worse than 96% of steel grades
  • Limited ductility — 11%, worse than 89% of steel grades
  • Limited service temperature — 250°C (482 °F), worse than 85% of steel grades
  • Low electrical conductivity — 6.5 % IACS, worse than 77% of steel grades

100CrMo7-4 +AC+C properties

Typical room-temperature values for 100CrMo7-4 +AC+C; 14 are specific to this condition. Other listed values are 100CrMo7-4 reference data and may not represent this condition. Bars are the position among steel grades.

Physical3

100CrMo7-4 +AC+C has a density of 7.83 g/cm³ (0.283 lb/in³), lighter than 80% of steel grades. It melts at 1,420°C (2,588 °F).

Density7.83 g/cm³0.28 lb/in³
Melting Point (Solidus)1,420°C2,588 °F
Liquidus Temperature1,465°C2,669 °F

Mechanical15

100CrMo7-4 +AC+C has a yield strength of 620 MPa (89.9 ksi) and a tensile strength of 780 MPa (113 ksi) — stronger than 78% of steel grades. Elongation at break is 11% and the elastic modulus is 210 GPa (30.5 Msi).

Elastic (Young's) Modulus210 GPa30.5 Msi
Shear Modulus80 GPa11.6 Msi
Bulk Modulus160 GPa23.2 Msi
Poisson's Ratio0.3
Tensile Strength (Ultimate)780 MPa113 ksi
Yield Strength (0.2% offset)620 MPa89.9 ksi
Elongation at Break11%
Reduction in Area38%
Compressive Strength430 MPa62.4 ksi
Shear Strength470 MPa68.2 ksi
Fatigue Strength (Endurance Limit)350 MPa50.8 ksi
Charpy V-Notch Impact (RT)15 J11.1 ft·lbf
Hardness, Brinell235 HB
Hardness, Rockwell B99 HRB
Hardness, Vickers247 HV

Thermal6

100CrMo7-4 +AC+C is rated for continuous service to 250°C (482 °F). It conducts heat at 44 W/m·K (25.4 BTU/hr·ft·°F), better than 57% of steel grades. Thermal expansion is 11.9 µm/m·K (6.61 µin/in·°F).

Thermal Conductivity44 W/m·K25.4 BTU/hr·ft·°F
Specific Heat Capacity460 J/kg·K0.11 BTU/lb·°F
Thermal Expansion (CTE, 20–100 °C)11.9 µm/m·K6.6 µin/in·°F
Latent Heat of Fusion250 J/g107 BTU/lb
Max Service Temperature (continuous)250°C482 °F
Min Service Temperature-40°C-40 °F

Electrical3

100CrMo7-4 +AC+C conducts electricity at 6.5 % IACS, worse than 77% of steel grades.

Electrical Conductivity6.5 % IACS
Electrical Resistivity2.7×10⁻⁷ Ω·m10.6 µΩ·in
Magnetic Responseferromagnetic

Chemical & Environmental3

Corrosion resistance is not recommended (11/100), worse than 73% of steel grades.

Galvanic Potential (seawater, vs SCE)-0.62 V
Corrosion ResistanceNot recommended11/100
Chemical Resistance SummaryRusts readily in humid air and water; requires preservative oil, phosphating or plating. Attacked by acids and chlorides; compatible with mineral/synthetic lubricants and dry hydrocarbons.

Sustainability4

Producing a kilogram of 100CrMo7-4 +AC+C takes about 33 MJ of energy and emits 2.3 kg of CO₂ — more than 76% of steel grades. Typical recycled content is 25%.

Embodied Energy (primary production)33 MJ/kg14,187 BTU/lb
Embodied Carbon (primary production)2.3 kg CO₂/kg
Embodied Water60 L/kg7.2 gal/lb
Typical Recycled Content25%

Manufacturability8

100CrMo7-4 +AC+C's machinability is fair (50/100, worse than 53% of steel grades); weldability not recommended (12/100); formability poor (25/100).

MachinabilityFair50/100
Machinability Rating (AISI 1212 = 100 %)45%
WeldabilityNot recommended12/100
Formability (cold)Poor25/100
CastabilityPoor30/100
Brazeability / SolderabilityFair45/100
PolishabilityExcellent85/100
Anodizing Responsen/a — ferrous alloy; use black oxide, phosphate or thin dense chrome instead

Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.

Working with 100CrMo7-4 +AC+C

Is 100CrMo7-4 easy to machine?

Machine only in the spheroidized (+AC) state with coated carbide at moderate speed; after hardening use CBN hard turning or grinding.

Can 100CrMo7-4 be welded?

Effectively non-weldable at ~1 %C — any fusion welding cracks; use shrink fits, bolting or friction welding with full post-weld heat treatment on non-critical joints.

Can 100CrMo7-4 be formed, bent or molded?

Cold ring rolling / cold heading possible only in fully spheroidized bar; hot forge 1050–1100 °C and cool slowly to avoid network carbides and flakes.

What surface finishes work on 100CrMo7-4?

Hardened raceways are ground and superfinished to Ra <0.05 µm; protect with preservative oil, phosphate, black oxide or thin dense chrome — no anodizing.

100CrMo7-4 chemical composition (wt %)

Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.

ElementSpec limit (wt %)Nominal
C0.92 – 1.050.98
Si0.2 – 0.40.3
Mn0.6 – 0.80.7
Cr1.65 – 1.951.8
MoMo addition gives deep hardenability in heavy sections0.4 – 0.60.5
P≤ 0.03—
S≤ 0.02—
Niresidual, max≤ 0.25—
Curesidual, max≤ 0.3—
Alresidual, max≤ 0.05—
O≤15 ppm total oxygen for bearing quality≤ 0—
Febalance—

100CrMo7-4 +AC+C — frequently asked

What is 100CrMo7-4 +AC+C used for?

100CrMo7-4 +AC+C is typically used for large-diameter rolling bearings, slewing ring bearings and heavy industrial bearing races. In short: heavy-section bearing steel; deep through-hardenability; bainite-hardened option available.

What is the yield strength of 100CrMo7-4 +AC+C?

100CrMo7-4 +AC+C has a typical yield strength of 620 MPa (89.9 ksi) and a tensile strength of 780 MPa (113 ksi) — stronger than 78% of steel grades. Strength varies by condition: see the 7 listed tempers.

Is 100CrMo7-4 +AC+C easy to machine?

Reasonably — machinability is rated fair (50/100, worse than 53% of steel grades). Machine only in the spheroidized (+AC) state with coated carbide at moderate speed; after hardening use CBN hard turning or grinding.

Can 100CrMo7-4 +AC+C be welded?

Not readily — weldability is rated not recommended (12/100). Effectively non-weldable at ~1 %C — any fusion welding cracks; use shrink fits, bolting or friction welding with full post-weld heat treatment on non-critical joints.

What surface finishes work on 100CrMo7-4 +AC+C?

Hardened raceways are ground and superfinished to Ra <0.05 µm; protect with preservative oil, phosphate, black oxide or thin dense chrome — no anodizing.

Can 100CrMo7-4 +AC+C be formed, bent or molded?

Cold ring rolling / cold heading possible only in fully spheroidized bar; hot forge 1050–1100 °C and cool slowly to avoid network carbides and flakes.

What is the maximum service temperature of 100CrMo7-4 +AC+C?

100CrMo7-4 +AC+C is rated for continuous use to about 250°C (482 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.

What is the difference between 100CrMo7-4 +AC and 100CrMo7-4-HR?

+AC is the default condition — standard stock condition for bearing-ring blanks: soft, globular carbide structure giving the best machinability and cold-forming behaviour before hardening. HR: mill-supplied as-rolled bar for re-heating/forging; hardness too high and structure too banded for direct machining. Yield strength is 410 MPa in +AC versus 560 MPa in HR.

Sources

  1. ISO 683-17 Heat-treatable steels, alloy steels and free-cutting steels — Part 17: Ball and roller bearing steels — ISO (2014)
  2. EN 10027-2 Designation systems for steels — Steel numbers (1.3538) — CEN (2015)
  3. ASM Handbook Vol. 1: Properties and Selection — Bearing Steels — ASM International (1990)
  4. Bearing steel bar datasheets (100Cr6 / 100CrMo7 / 100CrMo7-4 family) — Ovako / Sandvik / Böhler (2023)
  5. Machinery's Handbook — machinability ratings for high-carbon chromium steels — Industrial Press (2020)

Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.