With reasonable composition design and special metamorphic treatment process, martensite-bainite ductile iron can be obtained without austempering treatment. Its hardness is moderate and its impact toughness is high. It is suitable for making ball mill grinding balls, lining boards, etc. A variety of wear parts, especially in wet wear conditions with corrosive media, are more advantageous. The ball mill grinding ball (metal casting) produced by this material has the same cost as ordinary low-chromium cast iron, but the wear resistance of Concrete Pump Pipe is about twice that of low-chromium cast iron in lead-zinc mine.
In addition, tungsten alloy white cast iron has the characteristics of high hardness and good wear resistance, and is used for making mixer blades and slurry pump bodies, and the service life has reached the level of high chromium cast iron.
In tungsten alloy white cast iron, tungsten is distributed in the matrix and carbide, and tungsten can change the morphology and distribution of the carbide. The carbide in tungsten alloy white cast iron is M3C type. When it is distributed in a continuous network, the carbide is mainly M6C type, and the small amount is M23C6 type and M7C3 type. Its shape is a close-structured block with tight structure, which is austenite. Surrounded by the body; the carbide is mainly M6C type, a small amount of M7C3 type and M3C type, and its shape is broken or isolated.
Low-tungsten alloy white cast iron has low cost, but its eutectic carbide is distributed in a continuous network and has high brittleness. It has poor safety under the conditions of impact load, and low-tungsten alloy white cast iron is treated with strontium-potassium-sodium. The network structure of the eutectic carbide disappears completely and is agglomerated. Adding a very small amount (0.4%~0.7%, mass fraction) of alloying elements to standard high manganese steel can greatly improve the hardness and strength of high manganese steel and reduce the toughness. Adding rare earth (RE), magnesium, calcium and other elements can purify the grain boundary, improve the morphology and distribution of inclusions, and achieve grain boundary strengthening; adding elements such as rare earth and titanium can refine the structure and achieve fine grain strengthening. High manganese steel castings increase in strength and toughness simultaneously with grain refinement. In order to reduce the deformation and cracking of high manganese steel castings during heat treatment, save energy consumption, and further improve wear resistance, the residual heat quenching process of high manganese steel castings has been developed, that is, when the castings are solidified and cooled in the mold to 1050~1100 At °C, the form is immediately quenched into the water. This process can reduce heat treatment costs, shorten the production cycle, and improve the wear resistance of castings.
The Medium Manganese Steel of Concrete Pump Pipe is a new type of wear-resistant material obtained by appropriately reducing the manganese content on the basis of Mn13 and adding a certain amount of chromium to reduce the austenite stability. The domestically produced medium manganese steel has 13Mn7, 10Mn7Cr2 and other series. The wear resistance of medium manganese steel is greatly improved, but the impact toughness is reduced, and the work hardening rate is much higher than that of high manganese steel. Studies have shown that after adding a proper amount of tungsten water toughening in the medium manganese steel of Concrete Pump Pipe, the impact toughness of the medium manganese steel is increased by 40%, the tensile strength is increased by 10%, and the wear resistance is increased by 40%. The wear resistance of steel is increased by 40%.
