How to Improve the Hardness of Gray Cast Iron?

As an OEM Castings Supplier, share with you.

Grey Cast Iron Casting

1. Charge ratio: The method of charge ratio is pig iron + scrap steel + recharge material + recarburizer, and the nitrogen in the recarburizer is used to change the shape and length of graphite to increase the hardness of gray iron castings.

2. Control of chemical composition (1) Many smelting companies believe that sulfur is harmful. The lower the content of sulfur in molten iron, the better. In fact, this is not the case. "Silicon carbide" and "manganese-sulfur ratio" should be considered in gray iron castings. . That is, Mn=1.71S+(0.2~0.5). HT250 chemical composition table: CPSiMnTiS3~3.3≤0.121.65~2.050.7~1.1≤0.05≤0.12 (2) For low alloying, one or two alloying elements should be added. When adding, the content of carbon element should be considered and not blindly pursued hardness.

3. Overheating of molten iron For gray iron castings, increasing the temperature of molten iron within a certain range can refine the graphite, make the matrix denser, and increase the tensile strength and Brinell hardness of the cast iron. The overheating temperature of molten iron should be controlled at 1500-1530℃, and the overheating time should be controlled within 10min.

4. Inoculant and inoculation method The inoculation treatment of gray cast iron is usually to slowly add an inoculant (the most commonly used 75Si-Fe) in the molten iron after inoculation. The hardness of the gray cast iron after inoculation treatment will tend to be uniform, which improves the machine The processing performance also increases the strength of gray cast iron. The hardness of gray iron castings is between HB170-240.

Our company also has Grey Cast Iron Casting on sale, welcome to contact us.