NM300 Abrasion Resistant Steel Plate

⚙️ Chinese high strength wear-resistant steel for construction machinery
🔥 Delivery: Quenched | Quenched+Tempered | TMCP+Tempered | Tempered | Hot rolled

📌 Designation method

The designation of the steel consists of the pinyin initial letters "NM" for "wear-resistant" and the specified surface Brinell hardness value. For steel requiring low-temperature toughness, the designation consists of the pinyin initial letters "NM" for "wear-resistant", the specified surface Brinell hardness value, and the quality class symbol (D, E).

Example 1: NM300    NM - pinyin initial letters for "wear-resistant"; 300 - surface Brinell hardness value.

Example 2: NM300D    NM - pinyin initial letters for "wear-resistant"; 300 - surface Brinell hardness value; D - quality class symbol.

🧪 Chemical Composition (mass fraction / %)

Grade Chemical composition (mass fraction) / %
C Si Mn P S Cr Ni Mo Ti B Als
≤ ≤ ≤ ≤ ≤ ≤ ≤ ≤ ≤ range ≥
NM300 0.23 0.70 1.60 0.025 0.015 0.7 0.50 0.4 0.05 0.0005–0.006 0.01
ⓘ Maximum values except B (range) and Als (min 0.01). Conforms to NM300 specification.

📊 Mechanical Properties & Process Performance

Grade Thickness (mm) Tensile Rm (MPa) Elongation A (%) Impact -20°C KV2 (J) Surface Brinell hardness (HBW)
NM300 ≤80 ≥1000 ≥14 ≥24 270 – 330
📌 Note: Tensile strength, elongation and impact energy are special performance requirements. If not specified in contract, only Brinell hardness (270–330 HBW) is guaranteed.
⚙️ Delivery condition: quenched; quenched tempered; TMCP tempered; tempered or hot rolled.

⚙️ Technical requirements

7.1.2 On the premise of ensuring the steel properties, the alloying elements Cr, Ni, Mo specified in Table 2 and Table 3 may be added individually or in combination. Other alloying elements not specified in Table 2 and Table 3 may also be added. Their alloying elements and contents shall be indicated in the quality certificate.

7.1.3 When Cu is present as a residual element in the steel, its content shall not be greater than 0.30%; the As content shall not be greater than 0.08%. If the supplier can guarantee it, analysis is not required.

7.1.4 The carbon equivalent of steel requiring low-temperature toughness shall comply with the requirements of Table 3. The carbon equivalent is calculated according to formula (1):
CEV = C + Mn/6 + (Cr+Mo+V)/5 + (Cu+Ni)/15

7.1.5 When using total aluminum (Alt) content calculation, the Alt content shall not be less than 0.015%, and for steel requiring low-temperature toughness, the Alt content shall not be less than 0.020%.

7.1.6 After negotiation between the supplier and the buyer and specified in the contract, the chemical composition of TiC-reinforced steel shall comply with Appendix A.

7.1.7 When the buyer requires finished product chemical composition analysis, the allowable deviation of the finished product chemical composition shall comply with the provisions of GB/T 222.

7.2 Smelting method
The steel shall be smelted in a converter or electric furnace and subjected to ladle refining.

7.3 Delivery condition
The steel shall be delivered in the quenched, quenched + tempered, TMCP + tempered condition, or in the hot-rolled condition (hot-rolled steel before heat treatment).

⚖️ NM300 vs Mild Steel — Q235 / ASTM A36 Technical Comparison

Parameter NM300 Q235 / ASTM A36 Difference
Surface Hardness (HBW) 270 – 330 ~120 – 140 NM300: ~2.2x higher
Relative Wear Resistance (ASTM G65) Low mass loss (reference) 3.5–4.5x higher mass loss NM300 superior
Typical Service Life (10mm liner, ore chute) 12 – 18 months 3 – 5 months NM300: 250%–350% longer
Primary Applications High-wear zones: mining, earthmoving, material handling Structural frames, supports, low-wear environments Application-specific selection
Relative Material Cost 1.8–2.2x baseline Baseline (1.0x) NM300 higher initial cost
⏱️
Service Life Extension
Field data indicates NM300 extends service life by 250%–350% in sliding abrasion applications compared to mild steel, directly reducing maintenance frequency and component replacement intervals.
💰
Total Cost of Ownership
Despite higher procurement cost, the total cost of ownership is 40%–60% lower for NM300 in high-wear environments due to extended operational life and reduced downtime.
🏗️
Design Consideration
A common engineering practice: specify NM300 for high-wear zones and Q235/A36 for structural frames, optimizing both performance and material cost.

📋 Standards and Inspection — GB/T 24186-2022

📄
Applicable Standard
GB/T 24186-2022
Engineering machinery high strength abrasion resistant steel plate and strip
🔍
Inspection Items
  • Chemical composition (per heat)
  • Surface Brinell hardness (per batch) — 270–330 HBW
  • Impact test for D/E grades (-20°C / -40°C)
  • Flatness — Class H per GB/T 709-2019
🎯
Sampling & NDT
Sampling: One sample per 60 tons max.
NDT: Available upon agreement (UT per ASTM A578)

🔥 Welding & Processing Notes — Practical Guidelines

✅ Weldability
Acceptable. Low-hydrogen process (SMAW, GMAW, FCAW) is recommended.
Consumables: ISO 18275 E69X X X / AWS A5.5 E11018M.
HAZ hardness limit: ≤ 400 HBW for field welding.
🌡️ Preheat Requirement
Required for thickness ≥ 20mm.
Minimum preheat: 100°C – 150°C (CEV ~0.45 max)
Interpass temperature: ≤ 250°C
For restrained joints: up to 175°C.
✂️ Cutting Methods
• Plasma cutting (recommended ≤ 50mm)
• Laser cutting (≤ 20mm)
• Abrasive waterjet — minimal HAZ
• Oxy-fuel — acceptable, hardened edge up to 3mm
🛠️ Post-cut treatment: HAZ removal by grinding is recommended if subsequent bending or forming is required. Stress relief at 550°C–600°C for 2 hours if dimensional stability is critical.
📘 NM300 Approximate Grade Lookup Table →
📄 NM300 technical data sheet — CEHE Steel — Compiled from GB/T 24186-2022
Mill test certificates available upon request. Third-party inspection accepted.