Steel NM400
also Hardox 400
NM400 is a quenched-and-tempered abrasion-resistant plate of about 400 HBW (42 HRC) to GB/T 24186, the most common equivalent of Hardox 400.
Values for the Q&T condition
NM400 tempers and conditions
NM400 is supplied in 6 conditions, soft to hard. Q&T is the default FabDigit quotes; the values on this page are for it.
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 | — |
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 NM400?
NM400 is a quenched-and-tempered abrasion-resistant plate of about 400 HBW (42 HRC) to GB/T 24186, the most common equivalent of Hardox 400. Plate is used for liners, chutes and wear parts, with default properties of 1050 MPa yield, 1250 MPa tensile and 12 % elongation; sub-grades B–E tighten impact requirements. It is a wear plate rather than a structural steel: machinability is low, cold bending needs ≥3–4 t inner radius, the HAZ softens after welding, and hardness is lost above 250 °C service. Step up to NM450/NM500 for higher abrasion resistance. NM400 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). NM400 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).
What is NM400 used for?
- Mining bucket and shovel liners
- Crusher and transfer chutes
- Dump truck body liners
- Hopper and bin wear plates
- Screen and grizzly plates
- Conveyor skirt and wear strips
- Cement and aggregate plant liners
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
NM400 properties
Typical room-temperature values for NM400-Q&T; bars are the position among steel grades.
Physical3
NM400 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
NM400 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
NM400 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
NM400 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 NM400 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
NM400's machinability is poor (25/100, worse than 93% of steel grades); weldability good (55/100); formability poor (30/100).
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. NM400 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with NM400
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.
Manufacturability
The process limits FabDigit applies to NM400. Every NM400 part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
CNC machining
| Machinability | Fair25 / 100 |
|---|---|
| ISO material group | P.2 |
| Cutting speed (rough / finish) | 180 / 210 m/min |
| Minimum wall | 0.8 mm |
| Minimum internal radius | 1 mm |
| Drill depth limit | 5× diameter |
| Best surface (machined / polished) | Ra 1.6 / — |
| Hardenable after machining | No |
Sheet metal
| Formability | Fair30 / 100 |
|---|---|
| Weldability | Better55 / 100 |
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 |
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.
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).
Plating
CVD Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel NM400 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Trade names
- Hardox 400
How much does NM400 cost?
NM400 is a standard-cost steel ($$), cheaper than about 59% 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.
NM400 — frequently asked
What is NM400 used for?
NM400 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 NM400?
NM400 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 NM400 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 NM400 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 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.
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 is the maximum service temperature of NM400?
NM400 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.
How much does NM400 cost?
NM400 is a standard-cost steel ($$), cheaper than about 59% 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.
Can FabDigit make parts in NM400?
Yes — NM400 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; 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.