.k / Na-v Compound Modification Of High Chromium Cast Iron - Clad Hammerhead Developed

Hardness and toughness of hammer material are lower, which can not meet the need of work condition in which the hammer has low wear resistance and cracking resistance. Based on these problems existing in use of crusher hammer material, high chromium cast iron--carbon steel bimetal hammer was researched. So in this paper, the effect of K/Na-V compound modification and heat treatment on microstructure, mechanical properties and wear resistance of the high chromium cast iron were studied. At the same time, this article studied horizontal combined casting process and interfacial bonding of high chromium cast iron-carbon steel bimetal hammer.The results showed that the size of austenite became greatly fine with modification by K/Na-V, dendritic crystal greatly decreased, carbide changed from thick lath form to fine lath form and chrysanthemum form which dissevered matrix less seriously and continuity of matrix became stronger; hardness of the as-cast high chromium cast iron, hardness, toughness and wear resistance after heat treatment could be improved obviously. Impact fracture surface changed from quasi-cleavage fracture to cleavage fracture and dimple after modified by K/Na-V. And the high chromium white cast iron had best structure, comprehensive performance and wear resistance when the quality fraction of adding K/Na-V was 1.2%.The influence of heat treatment on the mechanics properties of the high chromium white cast iron had also been studied. The optimum heat treatment was air-quenching at 1000℃for 3h and air-temping at 450℃for 2h, after which the betterhardness(HRC: 65.5) and toughness (α_k: 6.4J/cm~2) of high-chromium cast iron wereobtained.Metallurgy coalescent bimetal hammer was fabricated in a plane resin sand mould in which the carbon steel and high chromium casting iron were poured in order. Through the analysis of microstructure, micro-hardness and linear scanning of electronic probe, the results indicated that it was necessary to keep the interval in pouring in the range of 8～14s before casting the high chromium casting iron in order to make two kinds of matenals bond together by metallurgy coalescence at the experimental condition. The combined interface had higher strength and impact toughness through shortening the pouring interval at which mixing pouring could not happen. And the impact toughness of composite hammer head was about twice of high chromium casting iron, which made it possible to make full use of high chromium casting iron's excellent wear resistance in practice under the impact condition.