Cast steel shot and manufacture method thereof

Abstract

The invention relates to a cast steel shot and a manufacture thereof. The cast steel shot comprises the chemical compositions in percent by mass: 0.30-0.40% of C, 0.1-0.2% of Si, 0.5-0.65% of Mn, 1.0-1.2% of Cr, 0-0.01% of S, 0-0.01% of P, and the balance iron and unavoidable impurity. The manufacture technology comprises: preparing materials and melting, namely melting the prepared raw material compositions to form molten steel, pouring into a tundish, and employing a deoxidizer for deoxidization; forming a shot, namely, pouring deoxidized molten steel into a centrifugation disk rotating at a high speed, tossing out the pill under the centrifugal effect, dropping into a cooling pool, fishing out and baking to dry, so as to obtain a formed as-cast steel shot; and performing heat treatment, namely, heating the formed as-cast steel shot to 870-880 DEG C, keeping for 30-40 min, performing water-cooling quenching, performing tempering processing at 400-500 DEG C for 50-80 min, after tempering, employing a steel-plate vibrating-screen water cooling process to perform rapid cooling, so as to prepare the cast steel shot. The method guarantees the steel shot to have high hardness and also prevents the steel shot from generating cracks in the process of centrifugation forming and heating quenching, thereby increasing the toughness and other advantages of the steel shot.

Description

technical field [0001] A cast steel shot and a manufacturing method thereof belong to the technical field of metal abrasives. Background technique [0002] At present, cast steel shot is widely used in surface cleaning, rust removal, paint removal and strengthening of parts in machinery, shipbuilding, automobile, aircraft and container manufacturing industries. With the increasing requirements for the surface quality of structural parts in aerospace, aviation and special fields and the enhancement of people's awareness of environmental protection, the research and development of special steel shots has become a hot research topic in recent years. A large number of steel parts that were originally treated with pickling are now mostly replaced by shot blasting to reduce the discharge of waste acid and sewage, which further increases the consumption of cast steel shots for shot blasting. At present, the cast steel shot products used at home and abroad mainly fall into two cate...

AI Technical Summary

Problems solved by technology

Due to the high carbon content (0.8-1.2wt.%C), the high-carbon cast steel shot is centrifuged or atomized into pellets and then cooled to room temperature to form a high-carbon sheet-like martensite structure and produce a large number of cracks. And tempering treatment, cracks will still exist, so it is brittle and not resistant to impact. It is easy to break during surface shot blasting, sand blast cleaning and shot peening strengthening, and the loss is large.

Low-carbon cast steel shot has low carbon content (less than 0.2wt.%C), high toughness, but low hardness, no wear resistance, and due to high melting point, poor fluidity of molten steel, large shrinkage, resulting in loose steel shot and many hollow defects. Although the so-called cycle life measured by the 100% substitution method is higher than that of high-carbon steel shots, when cleaning steel parts, due to the low hardness of low-carbon cast steel shots, low cleaning efficiency and long cleaning time, the actual consumption of cleaning the same amount of steel parts The low carbon steel shot has not decreased, sometimes it will increase

The steel shots that are easy to break and wear will also generate dust during the continuous throwing process, which will reduce the surface cleanliness of the cleaned steel parts

When the shot peening treatment is carried out to improve the fatigue strength, the broken high-carbon steel shot will also scratch the surface of the workpiece and reduce the fatigue strength