Corrosion resistance of magnesium alloy article surfaces

摘要

Surfaces of magnesium-base alloy workpieces may be mechanically worked and deformed to increase their resistance to corrosion, especially corrosion occurring in the presence of water or water and salt or other corrosive media. Workpiece surfaces that are to be thus protected are engaged in squeezing, sliding, and frictional contact with a suitable burnishing or other working tool that traverses the surface to compress and deform it and to refine the metallurgical grain structure. For example, the grain size is reduced in a surface layer that may extend to a depth of up to a few millimeters. And grain orientation is altered within that depth. The tool is not employed to intentionally remove material from the surface of the workpiece. The initial dimensioning of the workpiece may take into consideration the alteration of surfaces by the mechanical working process.

主权项

1. A method of producing a magnesium-based alloy surface layer on a surface of a magnesium alloy article to improve the resistance of the magnesium alloy surface to corrosion from contact with water, the method comprising:
traversing the surface of the article to be protected with a surface of a tool, by movement of the tool or of the article, and applying cooling liquid at cryogenic temperature to the article surface as the article surface is being traversed by the tool, the tool surface being pressed against the cryogenically-cooled surface of the article in sliding frictional contact to compress and deform the surface layer, without cutting material from the surface layer, to a predetermined depth to change the metallurgical grain structure of the surface layer, the tool repeatedly traversing the cryogenically-cooled surface while progressively advancing into continued engagement with the cryogenically-cooled surface, the changed surface layer having greater resistance to corrosion than an untreated region of the magnesium-based alloy article.