Steel 835M30
BS 835M30
835M30 is a British Standard high-nickel-chromium-molybdenum aircraft-quality alloy steel comparable to AISI 4330, supplied annealed or hardened and tempered to the T–Z classes.
Reference datasheet — 835M30 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 W condition
835M30 tempers and conditions
835M30 is supplied in 7 conditions, soft to hard. W is the default FabDigit quotes; the values on this page are for it.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed / softened (as-supplied for machining) | Choose for rough machining or forming before hardening; note the 4% Ni analysis stays relatively hard even after full annealing. | 560 | 800 | 18 | 22 HRC | — |
Hardened and tempered, 850–1000 MPa | Lowest H&T strength level; pick when maximum toughness and easiest machining/welding are wanted from this grade. | 730 | 920 | 16 | 27 HRC | — |
Hardened and tempered, 1000–1150 MPa | Common general-engineering H&T level for large-section shafts and couplings. | 890 | 1,075 | 14 | 33 HRC | — |
WDefault Solution heat treated (unstable) | Most widely stocked condition: good balance of ~1150 MPa strength, high toughness and full through-hardening in large sections. | 940 | 1,150 | 14 | 36 HRC | — |
Hardened and tempered, 1150–1300 MPa | Higher-strength aircraft/motorsport level where fatigue capacity matters more than machining ease. | 1,050 | 1,230 | 12 | 39 HRC | — |
Hardened and tempered, 1230–1380 MPa | High-strength landing-gear / torsion-shaft level; grinding usually replaces heavy turning. | 1,130 | 1,300 | 12 | 42 HRC | — |
Hardened and tempered, 1550 MPa minimum | Maximum strength condition for highly stressed aircraft parts; low tempering temperature means reduced toughness and high hydrogen-embrittlement sensitivity. | 1,400 | 1,620 | 9 | 49 HRC | — |
Supply forms, finishes and certifications
Ways 835M30 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
U | Hardened and tempered, 930–1080 MPa | Coating |
What is 835M30?
835M30 is a British Standard high-nickel-chromium-molybdenum aircraft-quality alloy steel comparable to AISI 4330, supplied annealed or hardened and tempered to the T–Z classes. It is selected where very high strength must be combined with usable weldability and good toughness, and is available as bar, billet and closed-die forgings for airframe and landing-gear work. Default-condition values are 940 MPa yield, 1150 MPa tensile strength, 14% elongation and 340 HB (36 HRC). Machinability is low (32/100), weldability is only moderate (40/100) and there is no corrosion resistance, so protective plating or paint is mandatory; 817M40 (4340) is the usual alternative when welding is not required. 835M30 has a density of 7.84 g/cm³ (0.283 lb/in³), lighter than 78% of steel grades. It melts at 1,420°C (2,588 °F). 835M30 has a yield strength of 940 MPa (136 ksi) and a tensile strength of 1,150 MPa (167 ksi) — stronger than 91% of steel grades. Elongation at break is 14% and the elastic modulus is 205 GPa (29.7 Msi).
What is 835M30 used for?
- aircraft landing gear
- structural fittings
- high-strength bolts
Advantages
- High strength — 940 MPa (136 ksi), better than 91% of steel grades
- Polishes to a fine finish — 65/100, better than 78% of steel grades
Limitations
- High embodied carbon — 2.9 kg CO₂/kg, worse than 91% of steel grades
- Difficult to machine — 32/100, worse than 87% of steel grades
- Low electrical conductivity — 5.5 % IACS, worse than 81% of steel grades
- Poor heat conductor — 33 W/m·K (19.1 BTU/hr·ft·°F), worse than 80% of steel grades
- Limited formability — 20/100, worse than 80% of steel grades
835M30 properties
Typical room-temperature values for 835M30-W; bars are the position among steel grades.
Physical3
835M30 has a density of 7.84 g/cm³ (0.283 lb/in³), lighter than 78% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical16
835M30 has a yield strength of 940 MPa (136 ksi) and a tensile strength of 1,150 MPa (167 ksi) — stronger than 91% of steel grades. Elongation at break is 14% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
835M30 is rated for continuous service to 400°C (752 °F). It conducts heat at 33 W/m·K (19.1 BTU/hr·ft·°F), worse than 80% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
835M30 conducts electricity at 5.5 % IACS, worse than 81% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (16/100), better than 79% of steel grades.
Sustainability4
Producing a kilogram of 835M30 takes about 36 MJ of energy and emits 2.9 kg of CO₂ — more than 89% of steel grades. Typical recycled content is 30%.
Manufacturability8
835M30's machinability is poor (32/100, worse than 87% of steel grades); weldability fair (40/100); formability poor (20/100).
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. 835M30 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 835M30
Is 835M30 easy to machine?
Machine in the annealed or ≤340 HB H&T condition with rigid setups, sharp carbide and generous coolant; above 400 HB switch to grinding or ceramic/CBN tooling, and allow for the grade's air-hardening tendency in heat-affected surfaces.
Can 835M30 be welded?
Weldable by TIG/MIG/SMAW with low-hydrogen consumables, 150–250 °C preheat maintained through welding and immediate stress relief/temper below the last tempering temperature; re-heat-treat critical joints made in the Y/Z conditions.
Can 835M30 be formed, bent or molded?
Hot forge 1150–850 °C then slow cool or anneal; cold forming is impractical at H&T strengths, so bends and upsets must be done before hardening.
835M30 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 |
|---|---|---|
| C | 0.27 – 0.33 | 0.3 |
| Si | 0.1 – 0.35 | 0.25 |
| Mn | 0.45 – 0.7 | 0.55 |
| Nigives the very high hardenability | 3.9 – 4.3 | 4.1 |
| Cr | 1.1 – 1.4 | 1.25 |
| Mosuppresses temper embrittlement | 0.2 – 0.35 | 0.28 |
| Pmax; aerospace melts typically ≤0.015 | ≤ 0.04 | |
| Smax; aerospace melts typically ≤0.015 | ≤ 0.04 | |
| Fe | balance |
What surface finishes work on 835M30?
Not corrosion resistant — protect with Cd, Zn-Ni or IVD aluminium plating, phosphate or primer/paint; bake at ~190 °C for 8–23 h after electroplating parts above ~1000 MPa to avoid hydrogen embrittlement.
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 835M30 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Similar grades
- 4330
How much does 835M30 cost?
835M30 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.
835M30 — frequently asked
What is 835M30 used for?
835M30 is typically used for aircraft landing gear, structural fittings and high-strength bolts. In short: weldable high-strength aircraft steel; 1150 MPa in default condition; air-hardening, low machinability.
What is the yield strength of 835M30?
835M30 has a typical yield strength of 940 MPa (136 ksi) and a tensile strength of 1,150 MPa (167 ksi) — stronger than 91% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is 835M30 easy to machine?
Not especially — machinability is rated poor (32/100, worse than 87% of steel grades). Machine in the annealed or ≤340 HB H&T condition with rigid setups, sharp carbide and generous coolant; above 400 HB switch to grinding or ceramic/CBN tooling, and allow for the grade's air-hardening tendency in heat-affected surfaces.
Can 835M30 be welded?
With care — weldability is rated fair (40/100). Weldable by TIG/MIG/SMAW with low-hydrogen consumables, 150–250 °C preheat maintained through welding and immediate stress relief/temper below the last tempering temperature; re-heat-treat critical joints made in the Y/Z conditions.
What surface finishes work on 835M30?
Not corrosion resistant — protect with Cd, Zn-Ni or IVD aluminium plating, phosphate or primer/paint; bake at ~190 °C for 8–23 h after electroplating parts above ~1000 MPa to avoid hydrogen embrittlement.
Can 835M30 be formed, bent or molded?
Hot forge 1150–850 °C then slow cool or anneal; cold forming is impractical at H&T strengths, so bends and upsets must be done before hardening.
What is the maximum service temperature of 835M30?
835M30 is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 835M30-W and 835M30-Z?
W is the default condition — most widely stocked condition: good balance of ~1150 MPa strength, high toughness and full through-hardening in large sections. Z: maximum strength condition for highly stressed aircraft parts; low tempering temperature means reduced toughness and high hydrogen-embrittlement sensitivity. Yield strength is 940 MPa in W versus 1,400 MPa in Z.
How much does 835M30 cost?
835M30 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 (1991)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.19 — Fatigue and Fracture — ASM International (1996)
- MMPDS-17 (4330V / low-alloy high-strength steels) — Battelle/FAA (2022)
- En30B / 835M30 alloy steel bar datasheet — UK alloy steel stockist (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.