Steel En30B
En30B is a 4 % nickel-chromium-molybdenum case-hardening alloy steel from the BS 970 family, cross-referenced to 9310, and is held annealed, normalized, in conditions T through Z, carburized or nitrided.
Reference datasheet — En30B is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the Cond W condition
En30B tempers and conditions
En30B is supplied in 11 conditions, soft to hard. Cond W is the default FabDigit quotes; the values on this page are for it.
Compare all 11 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
for machining and prior to carburizing | Choose for maximum machinability on complex parts that will be carburized or hardened afterwards. | 550 | 800 | 20 | 235 HB | — |
Normalized (air cooled from austenitizing) and high-temperature tempered | Intermediate stock condition for large forgings; grain refinement before final hardening. | 700 | 950 | 17 | 29 HRC | 5.8 % IACS |
Condition T | Lowest H&T strength class; pick when toughness and machinability matter more than strength. | 730 | 920 | 17 | 28 HRC | — |
Condition U | General-purpose shaft and bolt strength class with good impact toughness. | 800 | 1,000 | 15 | 31 HRC | — |
Condition V | Mid-range class for heavily loaded shafts and gear blanks in large sections. | 880 | 1,075 | 14 | 34 HRC | — |
Cond WDefault Condition W | Most commonly stocked H&T class — best balance of high strength and useful toughness in large diameters. | 980 | 1,150 | 13 | 37 HRC | — |
Nitrided after hardening and tempering | Use when a thin, distortion-free hard skin is needed on finish-machined H&T parts. | 1,000 | 1,150 | 11 | 61 HRC | 5.5 % IACS |
Carburized, hardened and low-temperature tempered (case-hardened) | Pick for gears, cams and splines needing a 60+ HRC wear surface over a 1100–1250 MPa tough core. | 1,020 | 1,200 | 11 | 61 HRC | — |
Condition X | High-strength class for aerospace bolts, links and torsion members; machine before hardening where possible. | 1,050 | 1,225 | 12 | 40 HRC | — |
Condition Y | Very high strength class; check notch sensitivity and hydrogen embrittlement risk when plating. | 1,120 | 1,300 | 11 | 42 HRC | — |
Condition Z | Maximum strength class (aircraft-quality bolts, high-stress links); low ductility and toughness, grind rather than machine. | 1,400 | 1,620 | 8 | 49 HRC | — |
What is En30B?
En30B is a 4 % nickel-chromium-molybdenum case-hardening alloy steel from the BS 970 family, cross-referenced to 9310, and is held annealed, normalized, in conditions T through Z, carburized or nitrided. Engineers specify it where a hard wear case must sit on a very strong, tough core: the default condition gives 980 MPa yield, 1150 MPa tensile, 13 % elongation and 340 HB (37 HRC), usually supplied as bar and forged gear blanks. Limits are a 350 °C maximum service temperature, low machinability (score 28), no corrosion resistance and an air-hardening composition that is effectively unweldable. Where core strength demands are lower, En34 is the simpler and cheaper carburizing choice. En30B has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,420°C (2,588 °F). En30B has a yield strength of 980 MPa (142 ksi) and a tensile strength of 1,150 MPa (167 ksi) — stronger than 91% of steel grades. Elongation at break is 13% and the elastic modulus is 207 GPa (30 Msi).
What is En30B used for?
- gears
- pins
- cams
- high-load bearings
Advantages
- High strength — 980 MPa (142 ksi), better than 91% of steel grades
- Polishes to a fine finish — 70/100, better than 87% of steel grades
Limitations
- Difficult to machine — 28/100, worse than 91% of steel grades
- Limited formability — 15/100, worse than 87% of steel grades
- Difficult to weld — 20/100, worse than 84% of steel grades
- High embodied carbon — 2.5 kg CO₂/kg, worse than 82% of steel grades
- Low electrical conductivity — 5.5 % IACS, worse than 81% of steel grades
En30B properties
Typical room-temperature values for En30B-Cond W; bars are the position among steel grades.
Physical3
En30B has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical16
En30B has a yield strength of 980 MPa (142 ksi) and a tensile strength of 1,150 MPa (167 ksi) — stronger than 91% of steel grades. Elongation at break is 13% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
En30B is rated for continuous service to 350°C (662 °F). It conducts heat at 34 W/m·K (19.6 BTU/hr·ft·°F), worse than 77% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
En30B conducts electricity at 5.5 % IACS, worse than 81% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (13/100), better than 66% of steel grades.
Sustainability4
Producing a kilogram of En30B takes about 36 MJ of energy and emits 2.5 kg of CO₂ — more than 89% of steel grades. Typical recycled content is 35%.
Manufacturability6
En30B's machinability is poor (28/100, worse than 91% of steel grades); weldability poor (20/100); formability poor (15/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the steel family
Yield strength against density for every steel grade FabDigit runs. En30B is highlighted; hover a dot for its name, or open the interactive family chart.
Working with En30B
Is En30B easy to machine?
Rough machine annealed (~235 HB) and finish after hardening by grinding; in condition W/X use rigid setups, sharp carbide or coated inserts, low speed with generous coolant, and stress-relieve before finishing.
Can En30B be welded?
Poor weldability — air-hardening 4% Ni-Cr-Mo steel; if unavoidable, preheat 250–350 °C, use low-hydrogen or matching consumables, and temper immediately after welding to avoid HAZ cracking.
Can En30B be formed, bent or molded?
Hot forge 1050–1150 °C with slow cooling and full anneal; cold forming is impractical above the annealed condition.
En30B 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.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| C835M30 / En30B carbon range | 0.26 – 0.34 | 0.3 |
| Si | 0.1 – 0.35 | 0.25 |
| Mn | 0.4 – 0.7 | 0.55 |
| Nigives deep hardenability and low-temperature toughness | 3.9 – 4.3 | 4.1 |
| Cr | 1.1 – 1.4 | 1.25 |
| Mosuppresses temper embrittlement | 0.15 – 0.3 | 0.25 |
| Pmax; aircraft quality often 0.025 max | ≤ 0.04 | |
| Smax; aircraft quality often 0.025 max | ≤ 0.04 | |
| Fe | balance |
What surface finishes work on En30B?
Takes hard chrome, zinc, cadmium and phosphate coatings well — bake at 190–210 °C after plating to relieve hydrogen; polishes and grinds cleanly for gear and bearing surfaces.
Surface treatments FabDigit runs on steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Organic Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel En30B in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Similar grades
- 9310
How much does En30B cost?
En30B is a premium-cost steel ($$$), cheaper than about 51% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
En30B — frequently asked
What is En30B used for?
En30B is typically used for gears, pins, cams and high-load bearings. In short: highest core strength carburizing steel; 9310-equivalent gear steel; hard case, tough core.
What is the yield strength of En30B?
En30B has a typical yield strength of 980 MPa (142 ksi) and a tensile strength of 1,150 MPa (167 ksi) — stronger than 91% of steel grades. Strength varies by condition: see the 11 listed tempers.
Is En30B easy to machine?
Not especially — machinability is rated poor (28/100, worse than 91% of steel grades). Rough machine annealed (~235 HB) and finish after hardening by grinding; in condition W/X use rigid setups, sharp carbide or coated inserts, low speed with generous coolant, and stress-relieve before finishing.
Can En30B be welded?
Not readily — weldability is rated poor (20/100). Poor weldability — air-hardening 4% Ni-Cr-Mo steel; if unavoidable, preheat 250–350 °C, use low-hydrogen or matching consumables, and temper immediately after welding to avoid HAZ cracking.
What surface finishes work on En30B?
Takes hard chrome, zinc, cadmium and phosphate coatings well — bake at 190–210 °C after plating to relieve hydrogen; polishes and grinds cleanly for gear and bearing surfaces.
Can En30B be formed, bent or molded?
Hot forge 1050–1150 °C with slow cooling and full anneal; cold forming is impractical above the annealed condition.
What is the maximum service temperature of En30B?
En30B is rated for continuous use to about 350°C (662 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does En30B cost?
En30B is a premium-cost steel ($$$), cheaper than about 51% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- BS 970-1: Wrought steels for mechanical and allied engineering purposes — 835M30 (En30B) — BSI (1983)
- BS 970-3 / BS S.106 aircraft-quality 4% Ni-Cr-Mo steel requirements — BSI (1991)
- ASM Handbook Vol.1: Properties and Selection — Irons, Steels and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.4: Heat Treating (carburizing and hardenability of Ni-Cr-Mo steels) — ASM International (1991)
- Machinery's Handbook (machinability ratings, alloy steels) — Industrial Press (2020)
- En30B (835M30) alloy steel bar datasheet — UK specialty steel stockists (e.g. West Yorkshire Steel / Smiths Metal Centres) (2023)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.