What Is NM600 Wear-Resistant Steel Plate?
NM600 is a high-hardness abrasion-resistant steel plate produced to Chinese wear-resistant steel practice. The designation NM stands for nai mo (wear-resistant in Chinese), and 600 refers to the nominal Brinell hardness of about 600 HBW. The plate is delivered in the quenched and tempered condition, which gives the surface extreme hardness for abrasion resistance while retaining a tempered martensitic structure for acceptable toughness. NM600 is engineered for the most severe wear conditions, where lower-grade plates such as NM400 or NM500 would wear out prematurely.
Hardness and Mechanical Properties
NM600 plate has a hardness of approximately 570-640 HBW, which is substantially higher than conventional structural steel and gives it long service life against sand, gravel, ore, and other abrasive media. The minimum elongation is 10%, and the plate is Charpy V-notch impact tested at -40 deg C with a minimum longitudinal impact energy of 20 J. The combination of extreme hardness and a guaranteed toughness level allows NM600 to withstand both sliding abrasion and moderate impact loading without cracking. Typical plate sizes range from 8 to 50 mm in thickness, 1450 to 4050 mm in width, and 3000 to 15000 mm in length, subject to mill capability.
Chemical Composition
The chemical composition of NM600 is controlled to balance hardness and toughness. Typical maximum values (percent by mass) for plate in the 8-30 mm thickness range include carbon about 0.45, silicon 0.7, manganese 1.00, phosphorus 0.015, sulfur 0.01, chromium 1.2, nickel 2.5, molybdenum 0.8, and boron 0.004, with a typical carbon equivalent of about 0.73 and a CET value of about 0.55. The nickel addition supports low-temperature toughness, while boron and the microalloy system promote hardenability during quenching. These are typical mill values, and the governing Chinese standard and the mill certificate should be consulted for the exact limits applicable to the ordered thickness.
Typical Applications
NM600 is used in environments involving severe mechanical wear, including mining equipment liners, crusher parts, excavator buckets, dump truck bodies, conveyor systems, and cement plant components. Its superior hardness allows it to withstand intense abrasion from sand, gravel, ore, and other abrasive materials, and its toughness reduces the risk of fracture in high-impact zones. In heavy equipment manufacturing, NM600 is selected for wear parts where downtime and replacement cost justify the higher material price compared with medium-hardness wear grades.
Cutting, Forming, and Welding Considerations
The ultra-high hardness of NM600 changes how the plate must be processed. Plasma and laser cutting are commonly used, and the heat-affected zone should be controlled to avoid excessive hardening and cracking; preheating or edge preparation may be required for thicker sections. Forming should be done with adequate bend radii and press capacity because the material has limited ductility at 600 HBW hardness. Welding of NM600 requires low-hydrogen consumables and strict heat input control, and welded joints are usually accepted with reduced wear performance at the weld zone; for maximum wear life, bolted or mechanically attached liners are often preferred over welding.
Frequently Asked Questions
What does the 600 in NM600 mean?? It refers to the nominal Brinell hardness of about 600 HBW, placing NM600 at the top of the common NM wear-resistant plate series.
How hard is NM600?? Typical hardness is 570-640 HBW in the quenched and tempered condition, which is significantly harder than NM400 or NM500 and gives long service life against sand, gravel, and ore.
Can NM600 be welded?? Yes, with low-hydrogen consumables and strict heat input control, but welded areas will not match the base plate hardness. For maximum wear life, bolted or mechanically attached liners are often preferred.
What is the maximum thickness of NM600?? NM600 is commonly supplied from 8 mm up to about 50 mm thickness, with width from 1450 mm to 4050 mm and length from 3000 mm to 15000 mm, subject to mill capability.
Is NM600 suitable for impact loading?? It has a guaranteed Charpy V-notch toughness at -40 deg C with a minimum longitudinal impact energy of 20 J, so it can withstand moderate impact. Very severe impact may favor a slightly softer grade with higher toughness.
What is the difference between NM600 and NM500?? NM600 has higher hardness of about 570-640 HBW versus about 470-540 HBW for NM500, which typically gives longer wear life in sliding abrasion at the cost of reduced ductility.
