Heat Treatment Technology of High Chromium Iron Castings

Update:10-02-2020
Summary:

As an anti-wear material, High Chrome White Iron Castin […]

As an anti-wear material, High Chrome White Iron Castings have not only necessary strength and toughness, but also their hardness is the most important quality index. Some high chromium iron castings can obtain the required hardness in the as-cast state, but most of them need heat treatment to meet the hardness requirements.

Heat treatment is almost a necessary process for every high chromium iron casting. Reasonable quenching can make the casting obtain the best ability to resist abrasive wear. Annealing can change the machinability of castings and enable them to be machined. There are also some heat treatment process measures that can improve the strength and toughness of castings and various service properties. It should be said that heat treatment is an important means to give full play to the performance potential of high chromium cast iron.

There are some differences between high chromium cast iron and alloy steel in quenching process specifications, which are mainly shown in the following aspects:

1. There are a large number of eutectic carbides in the structure of high chromium cast iron, which are different from matrix metal in thermal expansion and contraction and heat conduction. Rapid temperature changes in the heat treatment process will cause high thermal stress around carbides, which is easy to generate thermal cracks near carbides.

2. A large amount of carbon, chromium and other alloy elements are dissolved in austenite of high chromium cast iron, and a large amount of austenite is retained in the matrix structure after quenching. These residues not only affect the quenching hardness, but also cause the casting to crack or deform after quenching or during use.

3. When quenching high chromium cast iron parts, they must undergo destabilising treatment. The heating and mixing process of destabilising treatment depends on the carbon content of the material and the chromium-carbon ratio.

For details, please consult: https://www.wearresistantcasting.com/