On Weldability of Some Fully Killed Commercial Ship Steels

Abstract

To investigate the weldability of Japanese commercial ship structural steels, fourteen fully killed and two semi-killed steel plates, 25 to 35mm in thickness, were tested over a range of temperatures employing V-Charpy Test, Austrian-Standard-unnotched-bead-bend Test, and Knoop-hardness Test. Transitions from ductile to brittle behaviors were also observed.
In general, killed steels were found to be more hardenable in the heat affected zone than rimmed or semi-killed steels, and accordingly V-Charpy notch toughness is not enough to evaluate the weldability of killed steels.
The transition temperature determined by Austrian Bead Test was found to be closely associated with the combined parameter of V-Charpy transition temperature and maximum hardness in the heat affected zone. The Austrian Test, therefore, is considered to be a reasonable mean of V-Charpy and maximum hardness tests.
It was observed that with an unnotched bead such as in Austrian Test, the initial crack appeared sometimes in the weld-heat hardened zone in a comparatively hardenable steel. The bend performance, therefore, is greatly influenced by electrode types.