Shots made from zinc-based alloy

Abstract

Shots made from a zinc-based alloy is provided, wherein no risk for explosion caused by powder dusts exists. They achieve a high performance in deflashing and grinding and cleaning by shot blasting and a high ability to create a high compressive residual stress. The lost amounts of them by shooting are small. The shots are made from a zinc-based alloy that contains three components that include A1 of 0.5 to 6.5 mass % and Cu of 0.5 to 4.5 mass % as additional elements, or that contains four components that further include Mg of 0.01 to 0.2 mass % as additional elements, wherein the ratio of the mass of A1 to Cu (A1 / Cu) is 1.0 to 13.0, wherein the total amount of A1 and Cu (A1+Cu) is 1.5 to 10.5 mass %, and wherein the Vickers hardness of the shots is 90 to 190 HV.

Description

TECHNICAL FIELD[0001]The present invention relates to shots that are used for a process by projecting (by blowing) them, such as shot blasting or shot peening. The shot blasting is utilized to remove fins or burrs (below, “deflashing”) in nonferrous metallic parts, such as aluminum die-castings and aluminum castings, to strip sand from castings, to remove burnt deposits of coatings and parting agents, or to remove scales or flow lines (below, “grinding and cleaning”). The shot peening is utilized to improve the fatigue strength of nonferrous metallic parts or welded parts of nonferrous metallic parts.[0002]Herein, the wording “Vickers hardness” means the value measured in accordance with JIS Z 2244 under the condition that the applied force is 0.4093 N and the time for applying the force is 10 to 15 sec. It is expressed as “◯◯◯ HV 0.05,” abbreviated as “◯◯◯ HV.”[0003]The mark “%,” which is used to denote the contents of an alloy, means “mass %,” unless otherwise indicated.BACKGROUND...

AI Technical Summary

Benefits of technology

The present invention is about improving the hardness and toughness of shots made from zinc-based alloys, which are commonly used in shot blasting and shot peening processes. The invention involves adding specific components to the zinc-based alloy to achieve a Vickers hardness of about 100 HV and high toughness, without adding any element that is listed in the PRTR regulations. This solution allows for the development of more durable shots that can withstand environmental preservation regulations and work safety requirements.

Problems solved by technology

Thus the grinding and cleaning abilities are not sufficient.

Because of the characteristics of aluminum, a cloud of dust caused by breakages of the shots during shot blasting can easily burst.

Thus in view of work safety and environmental preservation, their use tends to be restricted.

Dust from shots made from zinc-based alloys cannot easily burst because of the breakages of the shots and because it takes a higher concentration to burst than those made from aluminum-based alloys and stainless steels.

Images