NM500 Steel Plate Hardness (HBW) Explained for Buyers

NM500 steel plate hardness (HBW) is the first number most buyers check when they specify a ~500 HBW abrasion resistant plate. Under GB/T 24186, NM500 is a high-strength wear plate whose grade name points to that nominal hardness class. This article explains what HBW means, which surface bands appear on our canonical NM500 page, and how NM500 compares with neighbouring NM grades - then points you to GB/T 24186 NM500 for full chemistry and RFQ data.

HENAN GANG IRON AND STEEL CO.,LTD (Gangsteel) supplies NM500 for export inquiry. Use the hardness bands below when drafting the purchase order; do not invent tighter limits than the ordered standard and MTC.

Canonical product page: GB/T 24186 NM500 holds chemistry, full hardness tables, sizes and RFQ fields. This article explains the topic in the title; it is not a second datasheet.

What is HBW (Brinell hardness)?

HBW means Brinell hardness measured with a tungsten-carbide ball indenter. Wear-plate grades such as NM400 or NM500 are named after a nominal surface hardness class (about 400 HBW or 500 HBW), not a single exact reading. Mills report a surface hardness band for a thickness range; buyers should put that band on the purchase order and check it on the mill test certificate.

On abrasion resistant plate, hardness is commonly checked a short depth below the plate surface on a milled spot (practice described on our grade pages). HBW is the language of wear-plate procurement; tensile strength alone does not replace it.

NM500 hardness by thickness

From the canonical GB/T 24186 NM500 page (public GB/T 24186 summaries as published there):

Grade	Thickness	Surface HBW	Center HBW (when required)
NM500	<=70 mm	470 to 540	420 to 540
NM500	>70 to 100 mm	450 to 540	-

Put the matching band for your thickness on the PO. Thicker plate uses the shifted surface band; center hardness is only when agreed.

NM grade hardness comparison (NM300 to NM600)

Use this map to see where NM500 sits. Each link uses the 标准+牌号 anchor pattern:

Grade	Nominal HBW	Primary surface band (from canon pages)	Product page
NM300	~300	270 to 330 (<=80 mm)	GB/T 24186 NM300
NM360	~360	330 to 400 (<=80 mm)	GB/T 24186 NM360
NM400	~400	370 to 430 (<=80 mm)	GB/T 24186 NM400
NM450	~450	420 to 480 (<=80 mm)	GB/T 24186 NM450
NM500	~500	470 to 540 (<=70 mm)	GB/T 24186 NM500
NM550	~550	520 to 580 (<=70 mm)	GB/T 24186 NM550
NM600	~600	570 to 640 (<=60 mm)	GB/T 24186 NM600

Bands above are copied from the canonical GB/T 24186 product pages on this site. Confirm the ordered edition and thickness on the MTC.

NM500 vs NM400 / NM450 / NM600

Grade	Primary surface HBW	When buyers usually pick it
GB/T 24186 NM400	370 to 430	Abrasion + better forming/welding balance
GB/T 24186 NM450	420 to 480	Middle step between 400 and 500 classes
GB/T 24186 NM500	470 to 540	Severe sliding abrasion; less forming
GB/T 24186 NM600	570 to 640	Ultra-high hardness; limited thickness/forming

NM500 vs AR500 / Hardox 500 neighborhood

AR500 and Hardox 500 sit in a similar hardness neighborhood for abrasion service, but they are not automatic dual certificates with GB/T 24186 NM500. On this site, commercial AR500 lives under the Carbon hub (AR500 / AR500F Steel Plate). Before substitution, compare hardness band, chemistry, impact and thickness on the MTC against the drawing.

Buyer tips for specifying NM500 hardness

1) Name GB/T 24186 NM500 plus thickness and the surface HBW band.
2) Say whether center hardness or impact (D/E) is required.
3) Ask for EN 10204 3.1 (or 3.2) listing hardness results.
4) Do not order "500 HBW exact" - order the band that matches the standard and your thickness.

FAQ

What is the hardness of NM500?

NM500 is named for a nominal surface hardness around 500 HBW under GB/T 24186. On our canonical page, public summaries list surface hardness about 470 to 540 HBW for thickness <=70 mm, and about 450 to 540 HBW for >70 to 100 mm, with a center hardness band (about 420 to 540 HBW) when that check is agreed. HBW is Brinell hardness, usually measured on a milled surface below the plate skin. Write the band that matches your thickness on the purchase order and check the same numbers on the MTC. Full tables: GB/T 24186 NM500.

Is NM500 the same as AR500?

They sit in a similar hardness neighborhood for abrasion service, but they are not automatic dual certificates. NM500 is ordered to GB/T 24186; AR500 is a commercial designation (on this site see AR500 / AR500F). Hardox 500 is a brand mill grade. Before substitution, compare surface HBW band, chemistry, impact, thickness and delivery condition on the MTC against the drawing - then decide with engineering approval.

NM500 hardness range for thick plate?

Yes - thickness changes the surface band. On GB/T 24186 NM500, the primary <=70 mm band is about 470 to 540 HBW; the thicker >70 to 100 mm band is about 450 to 540 HBW. Always order by grade + thickness + HBW band, not by the bare name "NM500". Confirm center hardness only if the PO asks for it.

How much longer does NM500 last vs mild steel?

In severe sliding abrasion, hardened wear plate typically lasts many times longer than mild or ordinary structural steel, but the multiplier depends on mineral type, impact, angle of attack, moisture and how the edge is cut/finished. Do not treat marketing life multiples as guarantees. Specify NM500 hardness correctly, protect cut edges when needed, and validate life with your own field trials. Datasheet: GB/T 24186 NM500.

NM500 vs NM450 - when is 500 HBW worth it?

Choose GB/T 24186 NM500 when sliding abrasion dominates and forming is limited. Choose GB/T 24186 NM450 (primary surface about 420 to 480 HBW for <=80 mm) when you need a middle hardness step with a bit more fabrication flexibility. If impact toughness is critical, discuss D/E options and test temperature on the PO. Compare both canon pages before you freeze the grade.

Ordering pointer

On the inquiry, write grade GB/T 24186 NM500, thickness, width, length, hardness band, delivery condition and certificate (3.1 or 3.2). Send RFQs via Gangsteel - HENAN GANG IRON AND STEEL CO.,LTD.