Hardness is an Important Quality Index of High Chromium Iron Castings

Update:03-01-2020
Summary:

As an anti-wear material, high chrome white iron castin […]

As an anti-wear material, high chrome white iron castings have the necessary strength and toughness, and their hardness is the most important quality index. Some high chrome 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 cutting performance of the casting and enable it to be machined. There are also some heat treatment measures that can improve the strength and toughness of the casting and improve various service properties. It should be said that heat treatment is an important means to give full play to the potential performance 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, brocade and other alloy elements are dissolved in the smelly body 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 dissolving fire, high-alloy iron castings must undergo destabilization treatment. The heat mixing and heat preservation process of destabilization treatment depends on the carbon content and chromium-carbon ratio of the materials.

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