NM400 vs Hardox 400: Hardness, Cost and When to Choose Each

NM400 vs Hardox 400 is a common buyer comparison: both sit near a ~400 HBW abrasion class, but one is ordered to GB/T 24186 and the other to a brand mill specification. This article explains hardness, cost drivers and when each choice makes sense, then funnels to the canonical GB/T 24186 NM400 product page for chemistry and RFQ fields.

If your drawing freezes "Hardox 400", keep that name unless engineering approves a documented substitute. If the PO accepts Chinese standard wear plate, GB/T 24186 NM400 is the datasheet to use.

Canonical product page: GB/T 24186 NM400 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.

NM400 hardness (from canonical page)

Grade	Thickness	Surface HBW
NM400	<=80 mm	370 to 430
NM400	>80 to 120 mm	360 to 440

Hardness map across GB/T 24186 grades

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.

NM400 vs Hardox 400 - practical differences

Topic	GB/T 24186 NM400	Hardox 400 (brand)
Spec basis	Chinese national standard grade	SSAB brand specification
Hardness class	Nominal ~400 HBW; band 370 to 430 (<=80 mm)	Brand ~400 HBW class (check mill card)
Substitution	Needs MTC comparison	Needs MTC / approval if swapping
On-site link	GB/T 24186 NM400	Brand name - not dual-cert by default

Commercial AR400 on this site: AR400 / AR400F Steel Plate. Same rule: neighborhood hardness, not automatic equivalence.

Cost and when to choose each

Choose NM400 when the project accepts GB/T 24186, you want Chinese-mill export supply with EN 10204 certificates, and the hardness/forming balance fits chutes, hoppers and liners.
Choose Hardox 400 when the end user or drawing names that brand, or when you specifically need that mill's documented package.
Landed cost depends on thickness, extras, freight and certificate scope - compare quotes on equal MTC requirements, not on the marketing name alone.

FAQ

Is NM400 the same as Hardox 400?

No. Both sit in a ~400 HBW abrasion class, but GB/T 24186 NM400 is ordered to GB/T 24186 while Hardox 400 follows an SSAB brand specification. Treat them as comparable hardness families for screening, not as automatic dual certificates. If the drawing names Hardox 400, keep that name unless engineering approves a documented substitute with matching MTC evidence.

What is the hardness of NM400 steel plate?

NM400 is named for a nominal surface hardness around 400 HBW. On our canonical page, public GB/T 24186 summaries list about 370 to 430 HBW for <=80 mm and about 360 to 440 HBW for >80 to 120 mm, with a center band when required. Hardness is checked as HBW (Brinell) on a prepared surface. Put the thickness-matching band on the PO and verify it on the MTC. Full tables: GB/T 24186 NM400.

When should I choose Hardox 400 instead of NM400?

Choose Hardox 400 when the end user or drawing freezes that brand, or when you specifically need that mill's documented toughness/forming package. Choose GB/T 24186 NM400 when the project accepts GB/T 24186, you want Chinese-mill export supply with EN 10204 certificates, and the ~400 HBW class fits chutes, hoppers and liners. Compare quotes on equal certificate and test requirements, not on the marketing name alone.

Does NM400 need mill test certificates for substitution?

Yes. Before substituting NM400 for Hardox 400 or AR400 (or the reverse), compare surface HBW band, chemistry, impact, thickness, delivery condition and any UT/Z extras on the MTC against the drawing. Commercial AR400 on this site: AR400 / AR400F. Without MTC comparison, "same hardness class" is not enough for quality acceptance.

NM400 vs Hardox 400 for chute and hopper liners?

Both are widely used for sliding abrasion liners. Selection usually comes down to the specified hardness band, formability, welding procedure, certificate scope and landed cost. For GB/T supply, start from GB/T 24186 NM400 and state the HBW band for your thickness. For brand-frozen projects, keep Hardox 400 and require the mill documents named on the PO.

Ordering pointer

On the inquiry, write grade GB/T 24186 NM400, 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.