“MGS01” new material, which add some chromium and rare-earth element in the high manganese steel. After using this new material, our customer reduces the consumption of the ball mill liner. Every set of ball mill liner can crush more than 750，000 tons of raw material. Compare with other material, the wear resistance of the board is increased by 34%.
Ball Mill Liner New Material Chemical Composition
- The main factor affecting the wear resistance of high manganese steel is the reasonable ratio of carbon to manganese. The carbon content is low, and after the heat treatment of the steel, the impact hardness is low, the wear resistance is poor, the carbon amount is too high, and the coarse-grained carbide is easily formed at the grain boundary after the heat treatment, so that the brittleness of the steel is increased and the wear resistance is also poor. If the content of manganese is high, the hardness after heat treatment is high and the cost is high. If the manganese content and the carbon content are appropriately reduced, the manganese-carbon ratio is optimally matched to 8 to 9, and not only the hardness but also the wear resistance can be improved after the heat treatment.
- The alloying elements vanadium, titanium, chromium, molybdenum, rare earth, etc. are all strong carbide forming elements. The special carbides formed in these high manganese steels are the key to improve the wear resistance of steel, especially the formation of dispersed carbides. Significantly improve the wear resistance of steel, but because vanadium, titanium, and molybdenum are relatively expensive, so choose the strong carbide elements that are economical and can improve the wear resistance, the preferred elements of chromium and rare earth. If the alloying element content in the steel is low, only Fe3C ordinary cementite can be formed, so only when the manganese chromium element and the carbon reach a certain ratio (about 118), a dispersive special carbide (C r7C2 or C r23C8, etc., which can significantly improve the wear resistance of steel.
- Determination of the dispersion hardening heat treatment process: The simulation schemes of the four dispersion hardening heat treatment processes are shown in Table 2.
After simulating four treatment schemes, the mechanical properties and metallographic structure show that the 2# heat treatment dispersion process: after 1080 ° C × 4 h water quenching, after tempering at 350 ° C, the carbides are fine at the grain boundary The particles and the fine needles are uniformly distributed, and the interface is chain-like, and the carbides reach a dispersion distribution. From the viewpoint of mechanical properties, the hardness is also high, the impact toughness is also high, and the tempering aging process has better strength than the 150 °C. Hardness and toughness. In the 450 °C tempering and mass-effect process, although the carbides also reach a dispersion distribution, large chain-like network carbides appear near the grain boundaries, so that the brittleness of the steel becomes large, which is unfavorable for wear resistance.
|Material||Heat Treatment||Hardness (HB)||Impact toughness (AK)||Carbide type and distribution status|
|Old Material||1080°C*4 hours Water quenching||217～220||20.9||There are needle-like, massive, granular carbides near the grain boundary, and the grain boundary network eliminates carbides as Fe8C.|
|New Material #1||1080°C*4 hours Water quenching+ 150°C Temper||220～240||20.2||A small number of particles and acicular carbides are evenly distributed in the grain boundaries. The grain boundaries are less chained and the carbide is Cr7C2.|
|New Material #2||1080°C*4 hours Water quenching+ 350°C Temper||260～280||22.3||Grain boundary fine particles and acicular carbides are uniformly distributed, and the grain boundaries are chain-like. The carbides are Cr7C2 and Cr23C8 (small amounts).|
|New Material #3||1080°C*4 hours Water quenching+ 450°C Temper||290～350||14.4||There are some large particles and long strips of carbides in the grain boundary, and the grain boundaries are chain-like. The carbides are Cr7C2 and Cr23C8 (small amounts).|
The Working Life Of Ball Mill Liner New Material
Our customer had ordered 83 pcs new ball mill liner and installed on 22th, July 2015. All new ball mill liner wear out on 9th, June 2016. In the working life, our new ball mill liner had crushed 759,000 tons (old material ball mill liner crushed 498,000 tons)