Steel NM450 QT-HT
Hardness band
also Hardox 450
QT-HT = q&T heavy plate
Thick plate where hardness is guaranteed only near the surface; mid-thickness hardenability drops, so use for thick liners and crusher jaws rather than for full-section strength design.
Values for the QT-HT condition
Other NM450 tempers and conditions
NM450 is listed in 4 conditions; see the grade overview at NM450.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
QT-HTThis page Q&T heavy plate | Thick plate where hardness is guaranteed only near the surface; mid-thickness hardenability drops, so use for thick liners and crusher jaws rather than for full-section strength design. | 1,150 | 1,380 | 11 | 46 HRC | 7 % IACS |
Q&T low-temperature toughness class | Cleaner, Ni-bearing heat with certified −40 °C Charpy (≥27–34 J) for mining and cold-climate structures where the wear plate also carries impact load. | 1,230 | 1,430 | 11 | 47 HRC | — |
QTDefault Quenched and tempered | Standard stocked condition for plate 4–80 mm; best balance of 450 HB wear life, bendability and weldability. | 1,250 | 1,450 | 10 | 47 HRC | — |
Direct-quenched (untempered / low-temperature stress relieved), thin… | Thin gauges (≈3–12 mm) supplied direct-quenched: hardness at the top of the band and highest strength, but the lowest impact toughness — pick only for pure sliding-wear liners with little bending or shock. | 1,300 | 1,550 | 8 | 49 HRC | — |
What is NM450 QT-HT?
NM450 QT-HT is NM450 heat treated to QT-HT — thick plate where hardness is guaranteed only near the surface; mid-thickness hardenability drops, so use for thick liners and crusher jaws rather than for full-section strength design. NM450 QT-HT has a yield strength of 1,150 MPa (167 ksi) and a tensile strength of 1,380 MPa (200 ksi) — stronger than 94% of steel grades. Elongation at break is 11% and the elastic modulus is 210 GPa (30.5 Msi). NM450 QT-HT 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). QT is the default condition FabDigit quotes; QT-HT is available on request or by drawing note.
Advantages
- High strength — 1,150 MPa (167 ksi), better than 94% of steel grades
Limitations
- Difficult to machine — 16/100, worse than 98% of steel grades
- Limited ductility — 11%, worse than 89% of steel grades
- Hard to polish — 45/100, worse than 84% of steel grades
- Limited formability — 20/100, worse than 80% of steel grades
- Limited service temperature — 300°C (572 °F), worse than 78% of steel grades
NM450 QT-HT properties
Typical room-temperature values for NM450 QT-HT; 22 are specific to this condition. Other listed values are NM450 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
NM450 QT-HT 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
NM450 QT-HT has a yield strength of 1,150 MPa (167 ksi) and a tensile strength of 1,380 MPa (200 ksi) — stronger than 94% of steel grades. Elongation at break is 11% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
NM450 QT-HT is rated for continuous service to 300°C (572 °F). It conducts heat at 38 W/m·K (22 BTU/hr·ft·°F), worse than 69% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
NM450 QT-HT conducts electricity at 7 % IACS, worse than 74% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of NM450 QT-HT takes about 30 MJ of energy and emits 2.3 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 25%.
Manufacturability7
NM450 QT-HT's machinability is poor (16/100, worse than 98% of steel grades); weldability good (62/100); formability poor (20/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with NM450 QT-HT
Is NM450 easy to machine?
Treat as 47 HRC martensite: rigid setups, coated carbide or CBN, low speed and heavy-duty coolant; drilling and tapping are difficult, so prefer plasma/laser cutting plus punched or pre-machined holes and design in as-cut edges.
Can NM450 be welded?
Weldable with low-hydrogen consumables of matching or lower strength (E7018/ER70S-6 class); preheat roughly 100–175 °C depending on thickness and CEV, keep interpass below ~225 °C, control heat input to limit HAZ softening, and never post-weld heat treat above the tempering temperature.
Can NM450 be formed, bent or molded?
Cold bend transverse to rolling direction with punch radius about 4–5 × thickness and generous die clearance; heavy sections need press-brake tonnage roughly 3× that of mild steel, and hot forming above ~250 °C destroys the quenched hardness.
What surface finishes work on NM450?
Supplied hot-rolled or shot-blasted; apply zinc-rich primer plus epoxy paint for outdoor storage, and avoid electroplating or acid pickling because of hydrogen-embrittlement risk at 450 HB.
NM450 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 |
|---|---|---|
| Cladle analysis, GB/T 24186 max | ≤ 0.26 | 0.2 |
| Si | ≤ 0.7 | 0.3 |
| Mn | ≤ 1.6 | 1.2 |
| P | ≤ 0.03 | 0.01 |
| S | ≤ 0.01 | 0 |
| Crhardenability | ≤ 1.2 | 0.5 |
| Niraised in low-temperature toughness class | ≤ 1 | 0.2 |
| Mo | ≤ 0.6 | 0.2 |
| Bboron-treated for deep hardening | ≤ 0.01 | 0 |
| Nbmicro-alloying, optional | ≤ 0.08 | 0.03 |
| Voptional | ≤ 0.08 | 0.02 |
| Tifixes N to protect boron | ≤ 0.05 | 0.02 |
| Altotal Al, deoxidation | ≥ 0.02 | 0.03 |
| Fe | balance | — |
NM450 QT-HT — frequently asked
What is NM450 QT-HT used for?
NM450 QT-HT is typically used for mining equipment liners, screen decks and wear plates. In short: standard mining wear plate; 450 HB abrasion resistance; hardox 450 equivalent.
What is the yield strength of NM450 QT-HT?
NM450 QT-HT has a typical yield strength of 1,150 MPa (167 ksi) and a tensile strength of 1,380 MPa (200 ksi) — stronger than 94% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is NM450 QT-HT easy to machine?
Not especially — machinability is rated poor (16/100, worse than 98% of steel grades). Treat as 47 HRC martensite: rigid setups, coated carbide or CBN, low speed and heavy-duty coolant; drilling and tapping are difficult, so prefer plasma/laser cutting plus punched or pre-machined holes and design in as-cut edges.
Can NM450 QT-HT be welded?
Yes — weldability is rated good (62/100). Weldable with low-hydrogen consumables of matching or lower strength (E7018/ER70S-6 class); preheat roughly 100–175 °C depending on thickness and CEV, keep interpass below ~225 °C, control heat input to limit HAZ softening, and never post-weld heat treat above the tempering temperature.
What surface finishes work on NM450 QT-HT?
Supplied hot-rolled or shot-blasted; apply zinc-rich primer plus epoxy paint for outdoor storage, and avoid electroplating or acid pickling because of hydrogen-embrittlement risk at 450 HB.
Can NM450 QT-HT be formed, bent or molded?
Cold bend transverse to rolling direction with punch radius about 4–5 × thickness and generous die clearance; heavy sections need press-brake tonnage roughly 3× that of mild steel, and hot forming above ~250 °C destroys the quenched hardness.
What is the maximum service temperature of NM450 QT-HT?
NM450 QT-HT is rated for continuous use to about 300°C (572 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between NM450-QT and NM450 QT-HT?
QT is the default condition — standard stocked condition for plate 4–80 mm; best balance of 450 HB wear life, bendability and weldability. QT-HT: thick plate where hardness is guaranteed only near the surface; mid-thickness hardenability drops, so use for thick liners and crusher jaws rather than for full-section strength design. Yield strength is 1,250 MPa in QT versus 1,150 MPa in QT-HT.
Sources
- GB/T 24186 (High-strength abrasion-resistant steel plate) (2022)
- Hardox 450 data sheet (comparison grade) — SSAB (2023)
- ASTM A514 / ASTM E140 hardness conversions — ASTM International (2019)
- ASM Handbook Vol. 1: Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
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.