Effect of Diffusible Hydrogen on Mechanical Properties of Underwater Welded Joints : Study on Improving the Mechanical Properties of Underwater Welded Joints (The 1st Report)

概要

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The effect of diffusible hydrogen on mechanical properties of underwater wet welded joints by gravity welding process is investigated. 4 and 6 mm diameter coated electrodes of floe types and SM41 steel base metals of 6 and 9 mm in thickness are used. Main results obtained are summarized as follows; (1) The volume of diffusible hydrogen in underwater weld is much more than that in air weld. H_w of underwater weld increases with an increasing weld heat input and welding current and with a decreasing thickness of base metal. However, H_w shows roughly a constant value regardless of welding current and thickness of base metal. (2) The mechanical properties of the underwater weld, that is, tensile strength, elongation, bending ductility and notch toughness, can be improved remarkably by post weld heat treatment. (3) The evolution process of hydrogen from bead and butt weld and the recovery process of the mechanical properties of welds are able to be analysed by using the one-dimensional weld model. Consequently it is made clear that the time factor τ = Dt/l_0^2, by which the greater part of diffusible hydrogen diffuses out of weld, should be selected as the condition of post weld heat treatment.
社団法人溶接学会の論文
1985-10-01