Studies on Weld Hardening of Steel (Report 1)

Measurement of Cooling Rates

Abstract

As the first part of studies on the weld hardening of heat affected zone in high tensile steels, the effects of various factors on the cooling rate at the bond of a long bead were investigated experimentally by measuring the heating and cooling thermal cycle with thermocouples.
The accuracy and the reproducibility of measurement were first discussed, and the studied factors included the location of thermocouple, size and thickness of specimen, initial plate temperature, heat input (welding current and welding speed), as well as the type of electrode coating.
The effects of various factors, namely temperature (T), initial plate temperature (T₀), welding current (I), welding speed (v), and plate thickness (t) on the cooling rates at the bond of a long bead welded on a plate were found to be summarized with an experimental parameter, P:
P=(T-T₀/I/v)^1.7×(1+2/π tan^-1t-t₀/α)
to, α: constant.