抄録
Tensile tests were carried out in molten zinc by using both welded and machined specimens with a modified reinforcement in order to investigate the factors which influence the“Liquid Metal Embrittlement”(LME) crack initiation of steel by molten zinc, and the relations between the stress-concentration factor (Kt) and the nominal tensile stress levels (σc), at which the LME cracking initiates, were examined.
The steel pipe welded with several pieces of steel plates was dipped into the molten zinc and its thermal stress distribution was analysed by using the FEM. It was shown that the thermal stresses produced increased as the dipping speed decreased.
By using the results of the FEM analysis, the dipping speed at which a crack would occur at the toe of the welded bead was decided, and the dipping experiment was carried out at this speed. The main results obtained are as follows:
(1) The stress-concentration resulting from the shape of specimens was more influential than the metallurgical effect for the crack initiation of welded joints in molten zinc.
(2) The thermal stress occurred when the steel structural members were dipped into molten zinc, and it increased as the dipping speed decreased. Thus, the increase in dipping speed was effective to prevent crack initiation.
