VR 400 ESR is a premium, ESR-refined, pre-hardened mould steel designed for high-performance plastic mould applications. It belongs to the advanced category of P20-based steels but offers exceptional improvements in purity, toughness, hardness uniformity, and surface finish capability. VR 400 ESR is processed through Electro Slag Remelting (ESR), a specialized metallurgical refining technique that significantly improves cleanliness and structural homogeneity.

This grade is typically supplied in a pre-hardened condition of 36–40 HRC, ensuring high strength and eliminating the need for further heat treatment, which reduces machining time and prevents dimensional distortion.

Why ESR Refining Makes VR 400 ESR Superior?

ESR refining removes non-metallic inclusions and produces an ultra-clean, fine-grained microstructure. This leads to:

1. Very high polishability

2. Exceptional toughness

3. Superior texturing response

4. Better fatigue resistance

5. Improved through-hardness even in large blocks

Because of these characteristics, VR 400 ESR is preferred for moulds requiring mirror polish, high precision, and long operational life.

Key Properties of VR 400 ESR

1. Ultra-High Cleanliness (ESR Grade)

The ESR process produces a cleaner and more homogeneous steel structure than conventional steelmaking. This ensures stable performance, excellent consistency, and reduced risk of micro-cracks.

2. Superior Polishability

VR 400 ESR is ideal for applications requiring optical-grade surface finish, such as clear plastics, lighting components, lenses, and high-gloss moulds. The absence of impurities allows a flawless mirror polish.

3. Enhanced Hardness Uniformity

With optimized alloying elements and ESR refining, VR 400 ESR maintains consistent hardness from the surface to the core, even in thick cross-sections above 400–600 mm.

4. High Toughness & Strength

The fine microstructure delivers excellent toughness, making the material resistant to cracking, impact, and thermal fatigue during moulding operations.

5. Excellent Machinability for Its Hardness Range

Despite its high hardness, these machines better than many conventional tool steels due to its purified microstructure.

6. Suitable for Nitriding

It can be nitrided to achieve surface hardness of 58–62 HRC, ensuring improved wear resistance and extended mould life.

7. Very Good Weldability

Repairs and engineering changes can be done reliably with proper welding procedures. ESR purity helps prevent welding defects, porosity, and hardness variation.

Common Applications

1. High-gloss injection moulds

2. Transparent plastic moulds (optical parts, lenses, covers)

3. Automotive interior & exterior moulds

4. High-precision blow moulds

5. Packaging industry moulds

6. Moulds requiring deep texturing or laser engraving

7. Large mould bases needing high hardness uniformity

Summary

VR 400 ESR is a high-end, pre-hardened mould steel offering premium cleanliness, excellent toughness, and unmatched polishability due to ESR technology. With stable hardness, superior machinability, and excellent wear resistance, it is one of the most reliable materials for manufacturing high-quality plastic injection moulds and precision components.