Steel En30B Carburized
Heat-treated state
Pick for gears, cams and splines needing a 60+ HRC wear surface over a 1100–1250 MPa tough core.
Values for the Carburized condition
Other En30B tempers and conditions
En30B is listed in 11 conditions; see the grade overview at En30B.
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 |
CarburizedThis page 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 Carburized?
En30B Carburized is En30B heat treated to Carburized — pick for gears, cams and splines needing a 60+ HRC wear surface over a 1100–1250 MPa tough core. En30B Carburized has a yield strength of 1,020 MPa (148 ksi) and a tensile strength of 1,200 MPa (174 ksi) — stronger than 92% of steel grades. Elongation at break is 11% and the elastic modulus is 207 GPa (30 Msi). En30B Carburized 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). Cond W is the default condition FabDigit quotes; Carburized is available on request or by drawing note.
Advantages
- High strength — 1,020 MPa (148 ksi), better than 92% of steel grades
- Polishes to a fine finish — 70/100, better than 87% of steel grades
Limitations
- Difficult to machine — 8/100, worse than 100% of steel grades
- Limited service temperature — 180°C (356 °F), worse than 98% of steel grades
- Limited ductility — 11%, worse than 89% of steel grades
- Limited formability — 15/100, worse than 87% of steel grades
- Difficult to weld — 20/100, worse than 84% of steel grades
En30B Carburized properties
Typical room-temperature values for En30B Carburized; 10 are specific to this condition. Other listed values are En30B reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
En30B Carburized 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 Carburized has a yield strength of 1,020 MPa (148 ksi) and a tensile strength of 1,200 MPa (174 ksi) — stronger than 92% of steel grades. Elongation at break is 11% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
En30B Carburized is rated for continuous service to 180°C (356 °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 Carburized 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 Carburized 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 Carburized's machinability is not recommended (8/100, worse than 100% of steel grades); weldability poor (20/100); formability poor (15/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with En30B Carburized
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.
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.
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 | — |
En30B Carburized — frequently asked
What is En30B Carburized used for?
En30B Carburized 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 Carburized?
En30B Carburized has a typical yield strength of 1,020 MPa (148 ksi) and a tensile strength of 1,200 MPa (174 ksi) — stronger than 92% of steel grades. Strength varies by condition: see the 11 listed tempers.
Is En30B Carburized easy to machine?
Not especially — machinability is rated not recommended (8/100, worse than 100% 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 Carburized 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 Carburized?
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 Carburized 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 Carburized?
En30B Carburized is rated for continuous use to about 180°C (356 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.