To provide a method which can quantify the liquid metal embrittleness crack during seam welding of galvanized steel sheets, such as seam welding of a steel tube using the galvanized steel sheets by a simple method and can evaluate the liquid metal embrittleness crackability of steel products.
The method for evaluating the liquid metal embrittleness crack during seam welding of the galvanized steel sheets comprises butting the galvanized steel sheets having galvanizing layers on either or both surfaces against each other, then exerting an upset to the butt zone and welding the same under electrical heating, air cooling the steel sheets after the end of the electric heating, loading the butt zone with a tensile stress of ≥20 to ≤80% of the tensile strength of the steel sheets at a temperature of a weld HAZ zone above the melting point of the galvanizing layers and below the Ar3 transformation point of the steel sheets, then measuring the thickness of the embrittleness layer in the weld HAZ zone and evaluating the liquid metal embrittleness crack during seam welding of the galvanized steel sheets in accordance with the ratio of the embrittleness layer thickness to the sheet-metal gage of the steel sheets.
KODAMA SHINJI
MIYAZAKI YASUNOBU
MIZUHASHI NOBUO
