Mould Steel Selection: Differences Between ST52, C45 and Hardox

The type of steel used in concrete mould manufacturing is one of the most critical factors directly affecting mould performance, durability and economic service life. Many variables such as production volume, the abrasive characteristics of the concrete mixture, press pressure and operating duration play a decisive role in steel selection.

The most commonly used steel types in the industry are ST52, C45 and Hardox. These three materials have significant differences in terms of strength, wear resistance and cost.

ST52 Steel: An Economical Option for Low-Intensity Production

ST52 is a structural steel with relatively lower strength values. Due to its economical cost, it is preferred in certain production scenarios.

However, the use of ST52 in concrete moulds is generally suitable for plants with lower production volumes and limited operating periods. This is because:

• Its wear resistance is lower compared to C45 and Hardox.
• The risk of deformation is higher under intense vibration and high pressing pressure.
• Maintenance requirements may increase in long-term serial production.

For this reason, ST52 is usually considered for cost-oriented projects or lighter production scenarios. For plants operating with intensive and continuous production, it may not be the most economical solution in the long term.

C45 Steel: Standard and Balanced Performance

C45 is the most commonly preferred carbon steel in concrete mould manufacturing. In terms of strength, machinability and cost balance, it is considered the standard-quality material in the industry.

The advantages of C45 include:

• Higher strength and rigidity compared to ST52
• Surface hardness can be increased through heat treatment
• Balanced performance in medium and high production volumes
• Strong cost–performance ratio

C45 is widely preferred in many concrete block and paving moulds because it maintains production continuity without excessively increasing investment costs.

For medium-scale plants and manufacturers with regular production operations, C45 usually provides the most balanced solution.

Hardox (Wear-Resistant Steel): Maximum Resistance in Critical Internal Surfaces

Hardox is a special steel with very high wear resistance. In concrete mould manufacturing, it is not used throughout the entire mould but strategically applied on internal surfaces exposed to the highest wear.

Especially in moulds for products such as blocks and kerbstones, Hardox reinforcement is preferred in areas that are highly exposed to deformation due to concrete friction, vibration and high press pressure.

At AK Mold and Machine, Hardox is applied in plate form on internal wear surfaces of the mould. Since these areas are continuously exposed to contact and friction during production, Hardox steel with a high hardness value (approximately 400–450 HB) significantly extends mould service life.

Advantages of using Hardox include:

• High wear resistance
• Reduced internal surface deformation
• Preservation of production stability
• Extended maintenance intervals
• Higher durability under intensive and continuous production

With this approach, instead of manufacturing the entire mould using costly materials, only the critical areas are reinforced, providing an optimal cost–performance balance.

Hardox is therefore a strategic internal reinforcement solution, particularly preferred in plants operating 24/7 with high production volumes.

Comparison Table

Our Strategic Approach

Hardox steel is not used throughout the entire mould; it is applied only on internal surfaces exposed to wear.

This approach ensures maximum durability in critical areas without causing unnecessary cost increases.

Our philosophy is not “to use the most expensive material”, but rather
“to use the right steel in the right place.”

Every production line is different. Therefore, steel selection should always be determined specifically for each project based on production intensity and the targeted service life.