Grade 1.2085, also known as X33CrS16, is a corrosion-resistant plastic mould steel widely used for injection mould tools that require improved rust resistance, reduced maintenance, and long tool life in humid or water-contact environments. Unlike conventional P20-type mould steels, 1.2085 contains high chromium content, which gives it natural corrosion resistance similar to semi-stainless tool steels.

It is typically supplied in a pre-hardened condition (typically 28–33 HRC), allowing manufacturers to machine the steel directly without additional heat treatment. This reduces production time and eliminates distortion risks associated with quenching and tempering.

Key Properties of Grade 1.2085

1. High Corrosion Resistance

The steel is designed to resist rust formation caused by:

a. Moisture

b. Cooling water channels

c. Condensation during moulding

d. Humid storage environments

e. Aggressive plastics

This property helps maintain mould surface quality and reduces maintenance.

2. Good Machinability

Although corrosion-resistant, 1.2085 machines better than most stainless tool steels due to its optimized sulphur content.
It supports milling, drilling, EDM, and polishing without excessive tool wear.

3. Stable Hardness & Dimensional Stability

In its pre-hardened state (28–33 HRC), the steel maintains good dimensional stability during machining and moulding operations.

4. Improved Wear Resistance

The chromium-rich matrix provides better wear resistance than low-alloy mould steels, making it suitable for medium-duty plastic moulds.

5. Excellent Weldability Compared to Other Stainless Tool Steels

Repairs can be performed with proper welding rods without severe hardness drops or cracking.

6. Good Polishability

1.2085 is capable of achieving a smooth, glossy surface finish—though it is not as polishable as ESR grades or high-purity steels like 1.2738 HH ESR.
However, it remains highly suitable for standard mould surfaces.

Common Applications

1. Injection moulds for corrosive plastics

2. Moulds used in humid or water-cooled environments

3. Mould components exposed to aggressive cooling systems

4. Medical equipment moulds

5. Packaging moulds

6. Moulds requiring reduced maintenance

7. Water-contact parts & components

8. Blow moulding tools

Summary

1.2085 is a corrosion-resistant plastic mould steel designed for environments where moisture and rust pose challenges. With its high chromium content, improved machinability, pre-hardened delivery, and stable performance, it is ideal for moulds that must stay rust-free, durable, and low-maintenance.