Examination for Establishment of Method of Taper Hardness Test

Abstract

To examine the relation between the maximum hardness of weld heat-affected zone and the cooling time from 800 to 500°C the method of taper hardness test has been used. At the standardization of this method for JIS, the authors corrected the defects of the old specification of the Japan Welding Engineering Society (WES) and carried out the measurement for studying the effects of bead length and heat reflection by the back and thinner edge of the specimen on the cooling time from 800 to 500°C, and for examination the difference of cooling time between the taper and flat specimen, and some calculations were carried out, too.
At the thinner part oflocal thickness, the cooling time from 800 to 500°C is controlled mainly by the bead length laid before and after passing of arc over the measured or calculated point and secondly by the effect of the thinner edge of the specimen. Measured value and calculated value were nearly equal and similar tendencies were obtained between them.