• The core purpose of this paper is to comprehensively compare the performance indicators, application scenarios, advantages and disadvantages of NM500 and NM550, as well as the precautions in their processing and use. Through in-depth analysis and practical cases, we will help readers to clearly understand the characteristics of these two materials, and provide scientific and practical advice, so that readers can choose the most suitable wear-resistant steel plate according to their needs, thereby optimizing equipment performance, reducing maintenance costs and improving production efficiency.

NM500 Steel is one steel grade in GB standard GB 24186. NM500 Steel is a high-strength, wear-resistant / abrasion resistant steel known for its superior hardness and durability. This steel is specifically designed to withstand high wear conditions and provide extended service life in challenging environments. With a hardness range of 470-540 HBW, NM500 is widely used in applications where resistance to abrasion is a primary concern, such as in mining equipment, construction machinery, and other heavy-duty applications. The strength of NM500 wear-resistant steel is more than 3 times that of ordinary low-alloy steel plates, and the wear-resistant performance can be increased by 2-3 times, significantly extending the service life of the steel plates.

2.2 What is NM550 Steel

2.3 Specification

NM500 and NM550 are both high-strength wear-resistant steel grades known for their superior hardness and durability.

Hardness:

• NM500 typically has a hardness range of 470-530 HBW.
• NM550 typically has a hardness range of 520-570 HBW.

Tensile Strength:

• NM500 has a minimum tensile strength of more than 1100 MPa.
• NM550 has a minimum tensile strength of more than 1250 MPa.

Impact Toughness:

• NM500 has an impact toughness of ≥27J at -20°C.
• NM550 has an impact energy of ≥27J at -20°C.

Elongation:

• NM500 has a minimum elongation of 18%.
• NM550 has a minimum elongation of 16%.

When comparing the processing and welding properties of NM500 and NM550 steel grades, several factors should be considered, including cutting and forming, welding performance, and heat treatment.

• Cutting and Forming:Both NM500 and NM550 steels can be cut and formed using standard methods for wear-resistant steels. However, due to the higher hardness of NM550, it may be slightly more challenging to cut and form compared to NM500. This could require more advanced technology and hardware facilities for processing such as cutting, drilling, bending, welding, etc., which increases the difficulty and cost of processing.
• Welding Performance:NM500 and NM550 steels are generally weldable, but the welding process may require special considerations due to their hard and tough microstructure. For NM550, tighter control of the preheating temperature may be required when welding to avoid hydrogen-induced cracking. It is important to use appropriate welding techniques and parameters to ensure good weld quality and minimize the risk of cracking.
• Heat Treatment:Heat treatment is an important process for both NM500 and NM550 steels to achieve the desired mechanical properties. The heat treatment process for NM550 may be more complex than for NM500 due to its higher hardness. The additional heat treatment process for NM550 can enhance its wear resistance and toughness. It is crucial to follow the recommended heat treatment procedures to ensure the steel reaches its full potential in terms of hardness and wear resistance.
• In summary, while both NM500 and NM550 steels offer excellent wear resistance and mechanical properties, NM550 may require more advanced processing techniques and tighter control during welding and heat treatment due to its higher hardness and strength.

NM500 and NM550 are both wear-resistant steel grades used in demanding applications where durability and resistance to wear are crucial.

• NM500 Applications:

NM500 steel is widely used in various industries such as mining, metallurgy, construction, and mechanical manufacturing, especially under severe wear conditions. It is suitable for making wear parts like excavator buckets, loader buckets, crusher hammers, and mill liners. It is also used for manufacturing wear-resistant plates, pipes, and elbows. NM500 steel demonstrates excellent wear resistance, high efficiency, cost savings, and environmental friendliness.

• NM550 Applications:

NM550 steel is known for its high hardness, high toughness, high strength, and low carbon and low alloy content, ensuring high wear resistance, easy processing, material savings, and cost reduction. It is used in earthmoving machinery such as loaders, bulldozers, excavator buckets, side blades, bottom blades, blades, and rotary drilling rigs. NM550 steel is also used in applications that require high wear resistance and can withstand extreme conditions.

• In summary, both NM500 and NM550 are used in heavy-duty applications where wear resistance is critical. NM500 is ideal for applications with high abrasion and impact stresses, while NM550 offers even higher wear resistance and is suitable for more extreme conditions.

Advantages of NM500

• Cost-Effective: NM500 is generally less expensive than NM550, making it suitable for less demanding applications.
• Good Machinability: Easier to machine than NM550.
• Moderate Strength: Ideal for general-purpose applications.

Disadvantages of NM500

• Limited Wear Resistance: Not suitable for high-stress molds.
• Lower Hardness: Not ideal for high-performance molds.

Advantages of NM550

• Higher Strength and Hardness: Ideal for high-wear applications.
• Better Wear Resistance: Suitable for high-performance injection molds.

Disadvantages of NM550

• Higher Cost: More expensive than NM500.
• Limited Weldability: Requires specific pre- and post-heat treatment.