How to strictly control the alloy content of high chromium wear-resistant hammerhead
Strictly control the alloy content of high chromium wear-resistant hammerhead.
1. Determination of carbon chromium. Carbon and chromium are the main elements that determine the matrix structure, carbide structure and properties of high chromium alloy cast iron. The amount of carbon determines the amount of eutectic carbide, and the amount of chromium determines the type of eutectic carbide.
2. According to the carbon content, the high chromium wear-resistant hammerheads are divided into three parts: low carbon area c2.0-2.5%, medium carbon area c2.5-2.8%, and high carbon area c2.8-3.4%. The lining plate of high chromium alloy cast iron is generally c2.5-2.8% in medium carbon area, the grinding ball of high chromium alloy cast iron is generally c2.0-2.5% in low carbon area, and the hammer casting of crusher is generally c2.8-3.4% in high carbon area.
3. According to the requirements of martensite structure obtained from the cast state of high chromium wear-resistant hammerhead, the carbon content should be c2.5-2.8% in the middle carbon area, the CR / C ratio should be 5.5-6.5, and the carbide content should be 21-25%. Therefore, the carbon content should be 2.4-2.8%, and the chromium content should be 14-18%. At this time, the eutectic carbide of high chromium alloy cast iron is intermittent acicular or globular, which can improve the microstructure hardness of M7C3 carbide to. Hv1500-1800, with strong toughness, can meet the use requirements of large mill liner.
4. 1.2 determination of silicon and manganese. Silicon is the limiting element in the high chromium wear-resistant hammerhead. The solubility of carbon in austenite is reduced when silicon dissolves into the matrix. The part of carbon that exceeds due to silicon dissolves into the matrix forms eutectic carbide with chromium, which weakens the solubility of chromium in austenite, makes austenite unstable and has the possibility of transformation from austenite to troostite. Therefore, silicon is a low hardenability element, but can improve MS point. Silicon is generally not added to high chromium alloy cast iron. Therefore, the silicon content should be ≤ 0.8%. Manganese is a conventional element, which dissolves into the matrix. Because austenite is not obtained, it is an element to improve hardenability and has the effect of deoxidization and sulfur removal. However, the content of MS point should not be more than 1%, so the content of manganese should be controlled at 0.4-1.0%.
5. 1.3 determination of copper element. When copper dissolves in the matrix, a certain amount of copper can improve the hardenability and impact toughness. At the same time, copper plays the same role as nickel element in the high chromium wear-resistant hammer head, which can partially replace nickel. Therefore, it is advisable to control copper element at 0.5-1.0%.