How Does Manganese Content (Mn13 vs. Mn18) Affect the Wear Resistance of Concave Materials? How to Choose for Different Material Hardness?

In the material selection for cone crusher concaves (bowl liners), high manganese steel dominates thanks to its unique work-hardening characteristics. The two most widely used grades are traditional high manganese steel represented by Mn13 (11%–14% Mn) and extra-high manganese steel represented by Mn18 (17%–19% Mn). The difference in manganese content directly affects the material's work-hardening capacity, surface hardness, and impact toughness, which in turn determines its wear performance when crushing materials of different hardness.

1. Work-Hardening Mechanism: The Core of High Manganese Steel's Wear Resistance

The wear resistance of high manganese steel does not come from its initial hardness, but from the work hardening triggered by impact loads during service. After water toughening, the matrix of high manganese steel is a single austenite structure with an initial hardness of about HB200, which by itself offers little wear resistance.

Under severe impact or high-pressure compression, the surface undergoes plastic deformation, forming high-density dislocations and deformation twins in the structure. The hardness can rise above HB500 while the inner layer retains excellent toughness, forming a "hard outside, tough inside" structure.

This property allows high manganese steel to withstand heavy impact loads without fracturing; even when worn very thin, it still maintains sufficient load-bearing capacity.

The level of work-hardening capacity directly determines whether a sufficiently thick hardened layer can form in service. If the hardened layer is too shallow and the surface hardness fails to reach the expected value, wear resistance will drop significantly.

2. Wear Resistance: Mn13 vs. Mn18

2.1 Basic difference in chemical composition

Both Mn13 and Mn18 belong to the austenitic high manganese steel family, and the core difference lies in manganese content. Mn13 typically contains 11%–14% Mn and 0.9%–1.35% C, and is the typical grade of the ZGMn13 series in the GB/T 5680 standard. Mn18 is an extra-high manganese steel containing 17%–19% Mn, usually alloyed with 1.5%–2.5% chromium (used as Mn18Cr2) in most industrial applications to improve hardenability and wear resistance.

Notably, higher manganese content is not always better. Under low-impact wear or pure abrasion conditions, traditional Mn13 may fail to fully trigger the martensitic transformation, resulting in poor wear resistance. This shows that the work-hardening capacity of high manganese steel depends not only on manganese content but also closely on the impact energy level.

2.2 Wear performance under impact

Impact abrasive wear tests provide quantitative comparison between Mn13 and Mn18. Under low impact energy, after 60 minutes of wear, Mn18 shows significantly better wear resistance than Mn13, and its worn-surface hardness grows slowly over time. At a higher impact energy (3.0 J), the wear resistance of Mn18 is about 1.5 times that of Mn13, and the worn-surface hardness can reach HB440 within a short time. This means that under sufficiently heavy impact loads, Mn18 achieves surface hardening faster and maintains a thicker hardened layer.

In terms of hardened-layer depth and the magnitude of wear-resistance improvement, Mn18 develops a deeper hardened layer under the same impact conditions, with wear resistance about 30% higher than Mn13. This improvement is of engineering significance for high-impact crushing applications (e.g., large cone crushers processing hard rock).

2.3 Synergy between carbon content and work hardening

Carbon and manganese jointly affect work-hardening capacity in high manganese steel. Research shows that increasing carbon content while reducing manganese content can enhance the work-hardening capacity of austenitic manganese steel; under non-severe impact conditions, high-carbon medium-manganese steel outperforms ordinary high manganese steel in both work-hardening capacity and service life. This suggests that the wear advantage of Mn18 relies more on the overall design of its alloy system than on manganese content alone. If manganese falls below 11%, a stable austenitic matrix cannot form, work hardening cannot be triggered under impact, and wear resistance drops by more than 50%. If carbon exceeds 1.4%, network carbides precipitate; although hardness increases, the matrix becomes more brittle and prone to cracking and spalling during wear, which actually shortens service life.

3. Effect of Material Hardness on Wear Resistance

3.1 Relationship between material hardness and liner wear

Material hardness is a key parameter affecting the wear rate of concaves. As material hardness increases, greater crushing force is required, and the cutting stress and contact stress on the liner surface increase accordingly. For high manganese steel, such conditions are actually favorable for forming and maintaining the work-hardened layer.

Take hard materials such as basalt (Mohs hardness 6–7) and granite (Mohs hardness 5–7): the high impact energy generated during crushing allows full work hardening of the high manganese steel surface, with hardened-layer hardness reaching above HB500 and wear potential well realized. When the material is soft (e.g., limestone, Mohs hardness 3–4), crushing is dominated by cutting and grinding with insufficient impact energy, so work hardening of high manganese steel is inadequate and its wear resistance is constrained. Feed size distribution also affects concave wear. Uneven or segregated feed accelerates localized liner wear; even with the right material choice, uneven wear may occur under improper operating conditions.

3.2 Guidance for material selection by material hardness

Material hardness can be classified into low hardness (Mohs < 4), medium hardness (Mohs 4–6), and high hardness (Mohs > 6). The suitability of Mn13 and Mn18 differs by class:

• Low-hardness materials: Low impact energy during crushing means insufficient work hardening; the actual difference in wear resistance between Mn13 and Mn18 is limited, and neither performs to its full potential. High chromium cast iron or other wear-resistant alloys may be more suitable.

• Medium-hardness materials: Impact energy is moderate; Mn13 triggers work hardening reliably and offers the best cost-performance ratio.

• High-hardness materials: High impact energy allows Mn18's advantages in hardened-layer depth and wear resistance to be fully realized, making it suitable for high-impact-frequency and strong cutting-wear conditions.

4. Material Selection Recommendations for Different Material Hardness

Based on impact energy, material hardness, and equipment characteristics, concave material selection can follow this framework:

Mn13Cr2 and Mn18Cr2 add chromium to traditional high manganese steel, compensating for its insufficient toughness under pure abrasion conditions and effectively extending the service life of wear parts. When materials are extremely hard and highly abrasive, bimetallic composite material is a worthwhile alternative: a high manganese or extra-high manganese steel matrix with hard alloy or ceramic particles inlaid on the working surface gives the wear face higher abrasion resistance while the non-wear faces retain excellent plasticity and impact toughness.

5. Practical Considerations in Material Selection

5.1 Heat-treatment quality matters

The performance of high manganese steel concaves depends not only on chemical composition but also critically on heat treatment. Castings must be water toughened (heated to about 1050°C and then water quenched), and the mechanical properties after treatment must meet the standard. Improper heat treatment (excessively fast heating, insufficient holding time, or inadequate quench cooling) prevents the formation of a single-phase austenitic structure even if the composition is correct, and work-hardening capacity will fall sharply.

5.2 Application limits of composite materials

Bimetallic composite materials, with hard alloy or ceramic particles inlaid in a high manganese steel matrix, achieve a synergy of hardness and toughness and offer a service-life advantage when crushing extremely hard materials. However, their cost is significantly higher than single high manganese steel; an economic evaluation based on cost per ton processed should be conducted before selection.

5.3 Measuring actual impact energy

"Impact energy" is not an abstract concept; it is a physical quantity directly related to feed size, crusher speed, and discharge setting. Selection should be based on feed size distribution, operating parameters, and actual conditions. When crushing large lumps of hard rock at high speed, impact energy is high and Mn18's wear advantage is fully realized; with uniform feed and stable operation, Mn13 may be more cost-effective.

5.4 Liner wear records and material tuning

Even with the same grade of high manganese steel, actual service life can differ significantly between foundries due to melting purity, heat-treatment control, and casting process. Establishing a liner wear record system (recording operating hours, tonnage processed, and wear patterns for each batch) and using accumulated data to fine-tune material selection and casting parameters is an effective management method. If surface spalling rather than normal wear occurs when crushing hard materials, first check whether the material is up to standard before judging a mismatch between operating conditions and material characteristics. If the material is qualified but the impact energy is insufficient to trigger full work hardening, consider adjusting the feed size distribution or switching to Mn18.