Hot cracking resistant mixed-crystal hard alloy and preparation method thereof

Abstract

The invention discloses a hot cracking resistant mixed-crystal hard alloy and a preparation method thereof. The hot cracking resistant mixed-crystal hard alloy comprises a hard phase, a bonding phraseand optional temperature resistant components. The hard phase comprises coarse tungsten carbide (WC) and fine WC. The ratio of the average crystal diameter of the coarse WC to the average crystal diameter of the fine WC is (1.7: 2.1). The average grain size of the hard alloy is between 2.4 Mu m and 3.4 Mu m. According to the hot cracking resistant mixed-crystal hard alloy provided, control over the average crystal diameter ratio of of the coarse WC to the fine WC is accurate; intensity is high; rigidity is high; and the hot cracking resistant property is good. When the hard alloy is used in an environment of thermal mechanical corrosion fatigue, crack initiation is late; hot crack growth is slow; the hard alloy is especially suitable for rolling of threaded steel on a small profile rolling mill; blocks are not easy to drop; rolled steel is good in quality; and the service life is improved by more than 20%.

Description

technical field [0001] The invention belongs to the technical field of hard alloys, and relates to a thermal cracking-resistant mixed crystal hard alloy and a preparation method thereof. Background technique [0002] Under normal circumstances, the toughness and wear resistance of cemented carbide are a pair of contradictions, and the strength and hardness are routine testing indicators. Fine-grained and ultra-fine-grained alloys can obtain high strength and high hardness at the same time, but their toughness is poor; coarse-grained high-binder phase alloys have better toughness, but their strength generally decreases with the decrease of hardness. To achieve better hardness and strength for coarse-grained high-binder phase cemented carbide, the conventional method is to use a longer ball milling time, but in this way, the grain size of the alloy decreases, which reduces the toughness and thermal conductivity of the alloy. For cemented carbide used under high temperature an...

AI Technical Summary

Problems solved by technology

In the preparation of twin crystal alloys, Fsss particle size is used to select raw materials, and the Fsss particle size range and matching ratio of coarse and fine WC are controlled. Most of them adopt batch ball milling technology in the ball milling process, and even prolong the ball milling time to achieve higher density. However, the Fsss particle size characterization is the size of WC particles, which cannot accurately reflect the real grain size of WC

Due to the fluctuation of raw material morphology, the crystallinity and activity of WC with the same Fsss particle size will be different, so that the grain size of WC with the same Fsss particle size will change, and then the wear resistance of WC will change. A variety of fluctuating WC grains undergo Ball milling and sintering make the ratio of coarse and fine grains in the twin crystal alloy structure also fluctuate, which directly leads to large fluctuations in performance

In some studies, the concept of optimizing the grain size and particle size of the alloy (grain distribution peak) is also proposed; magnetic force is also used to control the combination of coarse, medium and fine WC, but none of them can control the stability of the twin crystal structure.

Practice has proved that the accuracy and stability of the twin crystal structure affect its performance, which is the crux of the unstable quality of the twin crystal alloy

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