NM550 Wear Plate: the 550 HBW Class
NM550 is Baosteel's wear-resistant grade in the 550 HBW hardness class — one step above NM500 for applications that outwear 500 HBW plate, while keeping more forming margin than NM600. Baohui Steel supplies NM550 with the original Baosteel mill test certificate for every shipment.
International equivalents
| Mill / standard | Designation |
|---|---|
| Baosteel · GB/T 24186 | NM550 |
| SSAB (Sweden) | Hardox 550 |
| thyssenkrupp (Germany) | XAR 550 |
| Ruukki (Finland) | Raex 550 |
Real mill certificate data (delivered to Baohui)
Guaranteed values are one thing — delivered steel is another. An original Baosteel inspection certificate from a recent NM550 shipment delivered to Baohui Steel:
| Certificate No. | Issued | Size (mm) | Pcs / kg | Yield MPa | Tensile MPa | Elong. % | HBW (3 readings / avg) |
|---|---|---|---|---|---|---|---|
| BGSAI2609270002500 | 2026-09-27 | 5.0 × 1500 × 6000 | 6 / 2120 | 1612 | 1721 | 11 | 580 / 580 / 583 → 581 |
Every shipment includes the original Baosteel mill test certificate; SGS / BV third-party inspection can be arranged before loading.
Where NM550 fits: between NM500 and NM600
If NM500 liners reach end of life too early, but NM600 stretches the budget or the part still needs bending, NM550 is the middle point in the Baosteel wear program. Typical applications: loader and excavator bucket liners, crusher liners and hammers, chute and hopper liners, mixer blades, cutting edges and scraper blades.
Mechanical properties: guaranteed vs delivered
NM550 is specified under GB/T 24186 for quenched-and-tempered wear-resistant steel. The table contrasts the guaranteed minimums with values actually measured on the delivered certificate above:
| Property | Guaranteed (GB/T 24186) | Delivered — BGSAI2609270002500 |
|---|---|---|
| Brinell hardness | ≥ 530 HBW | 581 HBW average (580 / 580 / 583) |
| Yield strength | — | 1612 MPa |
| Tensile strength | ≥ 1600 MPa class | 1721 MPa |
| Elongation | — | 11 % |
A delivered hardness ~50 HBW above the guaranteed floor is what "550 HBW class" means in practice: consistent over-performance, plate after plate, not a best-case datasheet figure.
NM550 vs Hardox 550 vs XAR 550: the 550 HBW class compared
| Grade | Mill | Hardness (HBW) | Positioning |
|---|---|---|---|
| NM550 | Baosteel (GB/T 24186) | ≥ 530; delivered ~580 | Best price-performance in the 550 class; 1020 USD/MT FOB Shanghai |
| Hardox 550 | SSAB (Sweden) | 525–575 | Reference brand; sold through distributor network at a significant premium |
| XAR 550 | thyssenkrupp (Germany) | ~530–590 class | European mill alternative; project-specification driven |
| Raex 550 | Ruukki / SSAB Finland | ~550 class | Nordic mill alternative |
For buyers who specify "Hardox 550 or equivalent", NM550 is the equivalent — with the original Baosteel MTC to prove every heat. See the NM400 vs Hardox 400 analysis for the same comparison logic with real certificate data and pricing.
Applications by industry
Mining and quarrying. Dump truck bodies, loader and excavator bucket liners, crusher jaws and cones, screen plates and grizzly bars — anywhere 500 HBW plate wears through before the maintenance schedule allows.
Construction and earthmoving. Cutting edges and end bits, bulldozer blades, mixer truck drum liners, asphalt paver screeds and wear strips for concrete equipment.
Cement, concrete and aggregates. Raw mill liners, chute and hopper liners, chain conveyor flights, cyclone components — high-abrasion, moderate-impact duty where NM550 extends service intervals measurably.
Recycling and waste handling. Shredder hammers and anvils, grab and shear wear parts, trommel and sorting screens.
Fabrication and welding notes
At ~580 HBW delivered hardness, NM550 demands more discipline than NM400/450: keep cutting heat input low (plasma or laser with proper parameters), respect preheat for thicker sections, and use matching low-hydrogen consumables. Baosteel's official welding procedure — preheat temperatures, filler metal selection and real joint data — is summarized in our Baosteel welding guide. Our technical team answers grade-specific fabrication questions before you cut the first plate.
Sizes, stock and supply
Recently delivered: 5.0 × 1500 × 6000 mm plates, original Baosteel MTC. Other thicknesses and cut-to-length dimensions are supplied from program stock — single trial plates up to full container loads. Material ships from our Shanghai warehouse with SGS / BV third-party inspection available before loading. Ask for the current stock list and a firm quote.
