Abstract: The characteristics, classifications, and current application status of wear-resistant steel castings. It introduces typical wear-resistant steel castings and their production processes, elucidating the primary standards for wear-resistant steel. The aim is to contribute thoughtful insights and suggestions for the future development of the wear-resistant material industry in China.
1. Introduction
China’s wear-resistant steel material industry is renowned worldwide for its vast production scale and diverse product range. From austenitic manganese steel, white cast iron, non-manganese wear-resistant alloy steel, ductile iron, to iron-based composites, China boasts a wide variety of wear-resistant materials catering to numerous industrial sectors such as metallurgy, building materials, electricity, construction, machinery, national defense, shipbuilding, railways, coal, chemicals, and petrochemicals. Statistics indicate that China requires approximately 5 million tons of wear-resistant steel castings annually.
Wear-resistant steel castings constitute a significant category within wear-resistant castings, commonly used in large-scale heavy industrial production due to their excellent wear resistance and strength-toughness combination. China’s wear-resistant steels primarily encompass austenitic manganese steel and non-manganese wear-resistant alloy steel.
This article, combining national standards for wear-resistant steel castings with recent technological advancements in this field, focuses on the development and innovation of industrialization technologies to introduce wear-resistant steel castings and their trends. By exploring technical fields and analyzing development trends, we hope to provide beneficial reflections and suggestions for the future development of China’s wear-resistant material industry.
2. Classification of Wear-Resistant Steel
Table 1: Classification and Key Characteristics of Wear-Resistant Steel
| Classification | Sub-classification | Key Characteristics |
|---|---|---|
| Casting Wear-resistant Mn Steel | High Mn Steel (Mn13 series) | High surface hardening, good core toughness, widely used in equipment like ball mills, jaw crushers, etc. |
| Medium Mn Steel (Mn7) | Lower Mn content, higher wear resistance under non-severe impact conditions, suitable for applications with moderate impact. | |
| Ultra-high Mn Steel (Mn18 series) | Higher Mn content enhances austenitic stability, suitable for high-impact abrasive wear conditions. | |
| Non-Mn Wear-resistant Alloy Steel | Medium-carbon Low-alloy Steel | Good strength-toughness and hardness-toughness balance, widely used in excavator bucket teeth, ball mill liners, etc. |
| Medium-carbon Medium-alloy Steel | Higher wear resistance, suitable for applications requiring both impact resistance and wear resistance. | |
| Low-carbon High-alloy Steel | Recently developed, with potential for improved hardness and toughness. |
2.1 Casting Wear-resistant Mn Steel
- High Mn Steel (Mn13 series): Invented by R.A. Hadfield in 1882, high Mn steel is characterized by high surface hardening and maintained core toughness. The primary composition includes carbon at 0.7%-1.4% and manganese at 10%-14%. Alloying elements like chromium, molybdenum, nickel, and tungsten can be added to enhance properties.
- Medium Mn Steel (Mn7): With carbon content of 1.05%-1.40% and manganese of 5%-9%, medium Mn steel exhibits higher wear resistance than high Mn steel under non-severe impact conditions. The addition of molybdenum and chromium can further improve properties.
- Ultra-high Mn Steel (Mn18 series): Addressing issues of carbide precipitation and brittleness in thick sections, ultra-high Mn steel, such as ZG120Mn18 and ZG120Mn18Cr2, offers improved strength, plasticity, and wear resistance.
2.2 Non-Mn Wear-resistant Alloy Steel
Non-manganese wear-resistant alloy steels are distinguished by their high hardness, toughness, and strength, particularly their excellent hardness-toughness match. They are widely used in excavator bucket teeth, ball mill liners, hammer crusher hammers, and wear-resistant piping.
- Medium-carbon Low-alloy Steel: These steels offer adjustable mechanical properties, particularly hardness and toughness. They can be tailored for different applications by balancing strength, impact energy absorption, and wear resistance.
- Medium-carbon Medium-alloy Steel: These steels have higher wear resistance and can replace manganese steel in non-high-impact wear conditions.
- Low-carbon High-alloy Steel: Recently developed, these steels have potential for improved hardness and toughness.
3. Typical Castings and Production Processes
Table 2: Typical Wear-resistant Steel Castings and Their Production Processes
| Casting Type | Material | Production Process |
|---|---|---|
| High Mn Steel Casting | Mn13, Mn7, Mn18 series | Casting, heat treatment (water quenching for austenitization), and possible alloying addition for enhanced properties. |
| Non-Mn Alloy Steel Casting | Medium/Low-alloy Steel | Casting, followed by quenching and tempering to achieve desired hardness and toughness balance. |
4. Standards for Wear-Resistant Steel
4.1 Austenitic Mn Steel National Standards
Austenitic Mn steels, including standard Mn13, ultra-high Mn steels like Mn18 (Mn17) and Mn25, are produced and applied. Ultra-high Mn steels address issues of carbide precipitation in thick sections and potential brittleness at low temperatures. Standards emphasize controlling Si and P content, particularly P ≤ 0.04% for some export applications. such as V, Ti, Nb, and RE are often added to reduce inclusions, columnar grains, and coarse grains.
4.2 Non-Mn Wear-resistant Alloy Steel National Standards
The national standard GB/T 26651-2011 specifies 11 typical grades of non-Mn wear-resistant steel castings. These castings primarily contain C, Si, Mn, Cr, Mo, and Ni to ensure necessary strength, hardness, toughness, and hardenability. They are classified into low-alloy and medium-alloy steels. The standard mandates control of harmful elements S and P, with levels ≤ 0.04%. Heat treatment processes are not restricted, allowing suppliers to choose suitable methods based on technical requirements.
5. Conclusion
Recent advancements in austenitic Mn steel include stricter control of Si and P content, particularly P ≤ 0.04% for some exports, and the addition of trace elements like V, Ti, Nb, and RE to improve microstructure. For non-Mn wear-resistant alloy steels, particularly medium-carbon low- and medium-alloy steels, the trend is towards enhancing strength, hardness, and toughness combination to improve overall resistance to impact and wear.
With the rapid development of heavy machinery in China and increasingly demanding operational environments, the demand for wear-resistant materials is growing. Therefore, future development necessitates enhanced technological innovation, improved product quality, and reduced production costs to meet market demands. With continuous efforts and development, China’s wear-resistant material industry is poised for a brighter future, contributing significantly to the advancement of engineering fields.