Hypereutectic high-chromium white cast iron and preparation thereof

Abstract

The invention relates to wear-resistant white cast iron and a method for preparing the same, in particular to hypereutectic high-chromium white cast iron and a method for preparing the same. The cast iron is suitable for preparing an overflow part (such as an impeller, a guard board, a shell and so on) of a slurry pump or a Yellow River water pump for conveying eroding and abrading slurry. The compositions by weight percentage of the hypereutectic high chromium white cast iron are: 3.0 to 4.5 percent of C, 15 to 35 percent of Cr, 0.5 to 1.5 percent of Ti, 0.5 to 2.5 percent of Mn, 0.001 to 0.5 percent of B, 0.5 to 1.5 percent of Si, less than 0.06 percent of P, less than 0.06 percent of S, and the balance being Fe. The method comprises the following steps of: determining a proportion relation of the compositions, according to the compositions of the hypereutectic high-chromium white cast iron, and compositions of scrap steel, pig iron, high-carbon ferrochromium, ferromanganese, ferroboron and ferrotitanium; batching, melting, casting and heat treating to acquire a hypereutectic high chromium white cast iron material with a hardness between HRC 65 and HRC 68 and an impact ductility between 5.0 and 6.5 J / cm2.

Description

technical field [0001] The invention relates to a wear-resistant white cast iron and a preparation method thereof, in particular to a hypereutectic high-chromium white cast iron and a preparation method thereof. The cast iron is suitable for preparing slurry pumps and yellow pumps for transporting erosive wear slurry The flow parts (such as impeller, guard plate and shell, etc.). Background technique [0002] High chromium white cast iron is a kind of important wear-resistant material that is widely used. Due to the large amount of high hardness M in its structure 7 C 3 It has excellent wear resistance due to the presence of type carbides, and the morphology of the carbides is distributed in a rod shape, which improves the toughness compared with other white cast irons. The chromium element in high chromium white cast iron can not only effectively improve the corrosion resistance of the material in the slurry, but also the large amount of chromium-containing hard phase M ...

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Problems solved by technology

[0010] The main content of the paper "High Carbon and High Chromium White Cast Iron Materials and Its Application" published by Zhang Shangang and others is: under the condition of low temperature pouring, by adding a refiner to the molten iron (there is no component that provides the refiner) and 0.2-0.3mm alloy iron shot of about 1%, although the effect of refining primary carbides in the hypereutectic alloy (4.0-6.0C-30.0-40.0%) has been achieved, but due to the low-temperature casting method, the Castings are prone to defects such as cold shuts, resulting in low yield and unstable quality

In addition, due to the addition of about 2-3% molybdenum, the cost of raw materials increases, which is about three times the cost of KMTBCr26

[0011] The inventor of this patent application has used the method of inclined cooling body to refine the primary carbides in hypereutectic high-chromium white cast iron. Although the refinement effect is obvious, because the forming temperature of molten iron in this method is lower than the liquidus temperature, The formability is poor, and defects such as shrinkage cavities and porosity are prone to occur in castings, which limits the improvement of its toughness and wear resistance, which is not conducive to the promotion and use of industrialization

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