Steel NM400B
Grade
also Hardox 400
NM400B = q&T with 0 °C Charpy V-notch impact requirement
Pick when a certified room/0 °C impact value is required in addition to hardness.
Values for the NM400B condition
Other NM400 tempers and conditions
NM400 is listed in 6 conditions; see the grade overview at NM400.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
quenched & tempered heavy plate (> 40 mm), lower-bound hardness | Use for thick liners and wear blocks where quench-rate limits give hardness and toughness near the low end of the NM400 band. | 980 | 1,200 | 13 | 40 HRC | 8 % IACS |
Q&TDefault Quenched and tempered | Standard as-delivered condition of NM400 plate; pick it for general sliding-abrasion wear parts up to ~40 mm thickness. | 1,050 | 1,250 | 12 | 42 HRC | — |
NM400BThis page Q&T with 0 °C Charpy V-notch impact requirement | Pick when a certified room/0 °C impact value is required in addition to hardness. | 1,050 | 1,250 | 12 | 42 HRC | 8 % IACS |
Q&T with −20 °C Charpy V-notch impact requirement | Standard cold-climate option for mining and construction wear parts operating below freezing. | 1,050 | 1,250 | 12 | 42 HRC | 8 % IACS |
Q&T with −40 °C Charpy V-notch impact requirement | For severe cold service (northern China, Siberia-type climates) where impact-sensitive wear structures are welded. | 1,050 | 1,250 | 12 | 42 HRC | 8 % IACS |
Q&T with −60 °C Charpy V-notch impact requirement | Special order for extreme low-temperature impact-abrasion duty; requires tighter chemistry and cleanliness. | 1,050 | 1,250 | 13 | 42 HRC | 8 % IACS |
What is NM400B?
NM400B is NM400 in the NM400B grade — pick when a certified room/0 °C impact value is required in addition to hardness. NM400B has a yield strength of 1,050 MPa (152 ksi) and a tensile strength of 1,250 MPa (181 ksi) — stronger than 93% of steel grades. Elongation at break is 12% and the elastic modulus is 210 GPa (30.5 Msi). NM400B has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F). Q&T is the default condition FabDigit quotes; NM400B is available on request or by drawing note.
Advantages
- High strength — 1,050 MPa (152 ksi), better than 93% of steel grades
Limitations
- Difficult to machine — 25/100, worse than 93% of steel grades
- Limited service temperature — 250°C (482 °F), worse than 85% of steel grades
- Limited ductility — 12%, worse than 84% of steel grades
NM400B properties
Typical room-temperature values for NM400B; 23 are specific to this condition. Other listed values are NM400 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
NM400B has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F).
Mechanical16
NM400B has a yield strength of 1,050 MPa (152 ksi) and a tensile strength of 1,250 MPa (181 ksi) — stronger than 93% of steel grades. Elongation at break is 12% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
NM400B is rated for continuous service to 250°C (482 °F). It conducts heat at 40 W/m·K (23.1 BTU/hr·ft·°F), worse than 64% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
NM400B conducts electricity at 8 % IACS, better than 55% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of NM400B takes about 30 MJ of energy and emits 2.3 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 20%.
Manufacturability7
NM400B's machinability is poor (25/100, worse than 93% of steel grades); weldability good (55/100); formability poor (30/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with NM400B
Is NM400 easy to machine?
Machine only with rigid setups and carbide/CBN tooling at low speed and positive feed; drilling and tapping are difficult at 400 HBW — prefer plasma/laser/waterjet cutting plus pre-punched holes.
Can NM400 be welded?
Weldable with low-hydrogen electrodes or solid wire; preheat ~100–150 °C (higher for thick or restrained joints), keep interpass below ~250 °C, control heat input, and expect a softened HAZ — no PWHT above the tempering temperature.
Can NM400 be formed, bent or molded?
Cold bending possible with the bend axis transverse to rolling direction and inner radius ≥3–4 t; use generous die radii, deburr flame-cut edges first, and avoid hot forming above 250 °C to preserve hardness.
What surface finishes work on NM400?
Shot-blast and paint or epoxy-coat for corrosion protection; hard-chrome or thermal-spray overlays are used for extra wear life; not anodizable.
NM400 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 |
|---|---|---|
| CGB/T 24186 max; mills typically 0.16–0.22 for weldability | ≤ 0.3 | 0.2 |
| Si | ≤ 0.7 | 0.3 |
| Mn | ≤ 1.7 | 1.3 |
| P | ≤ 0.03 | 0.02 |
| S | ≤ 0.01 | 0 |
| Crhardenability addition | ≤ 1.2 | 0.5 |
| Niraised in low-temperature impact grades | ≤ 1 | 0.2 |
| Mo | ≤ 0.65 | 0.2 |
| Bboron-treated for through hardening | ≤ 0.01 | 0 |
| Tifixes N for effective boron | ≤ 0.05 | 0.02 |
| Nb | ≤ 0.07 | 0.02 |
| V | ≤ 0.1 | 0.02 |
| Altotal Al, deoxidation | ≥ 0.02 | 0.03 |
| Fe | balance | — |
NM400B — frequently asked
What is NM400B used for?
NM400B is typically used for mining bucket and shovel liners, crusher and transfer chutes, dump truck body liners, hopper and bin wear plates, screen and grizzly plates and conveyor skirt and wear strips. In short: workhorse Chinese wear plate.
What is the yield strength of NM400B?
NM400B has a typical yield strength of 1,050 MPa (152 ksi) and a tensile strength of 1,250 MPa (181 ksi) — stronger than 93% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is NM400B easy to machine?
Not especially — machinability is rated poor (25/100, worse than 93% of steel grades). Machine only with rigid setups and carbide/CBN tooling at low speed and positive feed; drilling and tapping are difficult at 400 HBW — prefer plasma/laser/waterjet cutting plus pre-punched holes.
Can NM400B be welded?
Yes — weldability is rated good (55/100). Weldable with low-hydrogen electrodes or solid wire; preheat ~100–150 °C (higher for thick or restrained joints), keep interpass below ~250 °C, control heat input, and expect a softened HAZ — no PWHT above the tempering temperature.
What surface finishes work on NM400B?
Shot-blast and paint or epoxy-coat for corrosion protection; hard-chrome or thermal-spray overlays are used for extra wear life; not anodizable.
Can NM400B be formed, bent or molded?
Cold bending possible with the bend axis transverse to rolling direction and inner radius ≥3–4 t; use generous die radii, deburr flame-cut edges first, and avoid hot forming above 250 °C to preserve hardness.
What is the maximum service temperature of NM400B?
NM400B 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 NM400 Q&T and NM400B?
Q&T is the default condition — standard as-delivered condition of NM400 plate; pick it for general sliding-abrasion wear parts up to ~40 mm thickness. NM400B: pick when a certified room/0 °C impact value is required in addition to hardness. Yield strength is 1,050 MPa in Q&T versus 1,050 MPa in NM400B.
Can FabDigit make parts in NM400B?
Yes — NM400B is available for CNC machining and sheet metal; every part is priced by an engineer rather than instantly. Upload a STEP file to get a price and a DFM check.
Sources
- Wear-resistant steel plate NM400 datasheet and welding guide — Baosteel / Ansteel / HBIS (2023)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels — ASM International (1990)
- ASM Handbook Vol.19 — Fatigue and Fracture — ASM International (1996)
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.