influence of the silicon in high chromium cast iron

Silicon is generally brought in by the charge (mainly ferrochrome and pig iron). Carbon ferrochromium generally contains silicon. The silicon content of low-carbon ferrochrome produced in my country is 1.5%~2.0%, and the upper limit of silicon content of high-carbon ferrochrome is 3.0%. The silicon content of pig iron is 1%~3%. When using these charge to prepare high chromium cast iron, at least 0.3% to 0.5% Si should be brought into the molten iron.

It is generally believed that the common content of silicon in high chromium cast iron is 0.4% to 0.8%. Above 0.8%, it belongs to alloying elements that can produce specific effects.

Silicon does not enter carbides but is dissolved in austenite or ferrite. The role of silicon in high chromium cast iron has the following two aspects:

1.Dissolved in the solid solution phase, it has a solid solution strengthening effect on the matrix. This solid solution strengthening effect is stronger than that of manganese, nickel, chromium, tungsten, molybdenum and vanadium. Silicon can significantly increase the elastic limit, yield strength, yield ratio, and fatigue strength of austenite and its transformation products. The improvement of these strength properties helps to improve the wear resistance of the material.

2.Compared with chromium and manganese, silicon has a greater affinity for oxygen. In the smelting process, silicon has a good deoxidizing ability and can prevent the oxidation of molten iron. In particular, it protects the high content of chromium in the molten iron and avoids excessive oxidation and burning of chromium. This is a very important function. If the silicon content of the molten iron is too low, such as less than 0.3%, the oxidation degree of the molten iron will increase significantly, the amount of element burning will increase, and the casting will produce oxidative pores and inclusions. The liquidity of molten iron will also decrease.

In the past, general high chromium cast iron standards stipulated that the silicon content of castings was mostly 0.5% to 0.8%. After recognizing these beneficial effects of silicon, high chromium cast iron allows the silicon content to be increased. In particular, the allowable silicon content range of medium chromium silicon cast iron and white cast iron has been increased to about 2%. Anyang Huatuo Metallurgy has in ferrochrome for more than 10 years, owned rich experience in the product, if any confused can contact us.