Medium carbon-rare earth alloy strengthening cast steel shot/grit and preparation technology thereof

Abstract

The invention provides medium carbon-rare earth alloy strengthening cast steel shot / grit and a preparation technology thereof, and belongs to the technical field of metal abrasives. The medium carbon-rare earth alloy strengthening cast steel shot / grit is characterized by being prepared from, by mass, 0.30%-0.85% of C, 0.30%-1.50% of Si, 0.30%-1.50% of Mn, 0.10%-0.15% of Re, 0.10%-0.90% of Cr, 0.01%-0.04% of Nb, smaller than or equal to 0.05% of P, smaller than or equal to 0.05% of S and the balance Fe. According to the medium carbon-rare earth alloy steel, by adding rare earth, molten steel is purified, and a grain structure of steel is refined; the strength, the hardness and the wear resistance are improved through chromium; niobium forms a carbide, and therefore the hardness and the wear resistance are improved; by means of alloy elements, the eutectoid temperature of the steel is increased, and diffusion of carbon is prevented. Accordingly, increase of the quenching temperature is beneficial for conversion from pearlite to austenite and diffusion of carbon. A metallographic structure is converted into tempered martensite and tempered troostite.

Description

technical field [0001] The medium-carbon rare earth alloy strengthened cast steel shot / sand and its preparation process belong to the technical field of metal abrasives. Background technique [0002] my country's current steel shot / sand material has been using the national standard GB6484 / 6485-86. Chemical composition (%) of high carbon cast steel shot / sand: C0.85~1.20, Si 0.40~1.50, Mn0.60~1.20, P≤0.05, S≤0.05. There are two defects in the forming and post-processing of the steel shot of this composition: one is that during the rapid polymerization and cooling forming, due to the high carbon content, there is serious composition segregation in the metallographic structure, and there are a large amount of secondary cementite. Distributed at the grain boundaries, the carbon atom-supersaturated martensite presents an irregular sheet structure, resulting in a large number of microcracks on the surface of the steel shot / sand. The second is that after the quenching and temperin...

AI Technical Summary

Problems solved by technology

There are two defects in the forming and post-processing of the steel shot of this composition: one is that during the rapid polymerization and cooling forming, due to the high carbon content, there is serious composition segregation in the metallographic structure, and there are a large amount of secondary cementite. Distributed at the grain boundaries, the supersaturated martensite with carbon atoms presents an irregular sheet structure, resulting in a large number of microcracks on the surface of the steel shot / sand

The second is that after the quenching and tempering treatment of the steel shot, although the metallographic structure has been improved to a certain extent, the micro-cracks in the performance are further expanded, resulting in the strength, toughness and wear resistance of the steel shot and sand not meeting the requirements, and the service life is generally in the 1200~1400 cycles

However, low-carbon steel shot is soft, the initial cleaning effect is poor, and it cannot be made into water chestnut sand, which limits the scope of use

The above problems have brought great inconvenience to the use of the current steel shot / sand, and a new type of steel shot / sand and its preparation process are urgently needed to solve the above problems