The Structure and Properties of Laser-Beam-Welded Joints of Steel Sheets with Al and Zn Coatings

摘要

An examination of the mi-crostructure, mechanical properties and corrosion resistance was conducted on laser-beam-welded low-carbon steel covered by immersion with anticorrosion coatings of Al and Zn. It was shown that during laser beam fusion welding of steel sheets with an Al coating, the Al layer was only removed for the width of the fusion zone, but in the case of welding the sheets with a Zn coating, the Zn outer layer was removed for the width of the fusion zone and heat-affected zone. To increase laser beam energy absorption, a layer of colloidal graphite was sprayed on the Zn coating. This was the cause of carbon penetration into the liquid metal during the welding process and the formation of a considerable amount of pearlite in the weld. Such joints with Al and Zn coatings that are laser welded have greater strength than the base material and feature good corrosion resistance.