Development of Zn-11 percent Al-2 percent Mg coated steel wire with excellent corrosion resistance and formability

摘要

A steel wire has been developed with an Mg-added Zn-ll percentAl coating that shows coiTosion resistance superior to that with Zn-10 percent Al. The characteristics of the newly developed wire are summarized as follows. Zn-ll percent Al-l ~ 3Mg coated wire can be made by double hot-dip method. The addition of Mg improves the anti-corrosion property outstandingly owing to the fme MgZn_2, however, a 250 SST showed that there is little difference in corrosion resistance between 1 percent and 3 percent Mg contents in coating metals, which implies that the coarse granular MgZn_2 appearing as secondary crystal in solidification of Zn-ll percentAl-3 percentMg, is not effective for corrosion resistance. When the coarse granular MgZn_2 exists, formability seemed to deteriorate. A Zn-ll percentAl-2 percentMg coated steel wire has been developed that shows an excellent combination of good corrosion resistance and formability by controlling the cooling rate during solidification which prevents the formation of the coarse granular MgZn_2.