厚鋼板の電子ビーム溶接 Ｉ ビーム特性の炭素鋼板の溶接条件の選定

Abstract

Relationship between welding conditions, bead shapes and occurrence of weld defects was investigated in flat, horizontal and vertical up position electron beam welding of heavy section carbon steel plates. As a result of these investigations, it was confirmed that sound full penetration welds could be made for carbon steels up to 150 mm thickness with proper beam oscillation.Main results obtained are as follows;(1) Beam shape at a beam current of above 160 mA is nearly parallel independently of focus coil currert.Beam diameter is given by the following equation;db=4.7×10-2(1/If)3.8Ib(mm), for Ib≤160 mA beam currentdb=1.4×10-2Ib+1.6(mm), for Ib>160 mA beam current(2) In flat position, penetration depth is given by the following experimental equation;hp=2.0⋅Ib/√ub (Ib/√ub>45)Occurrence of weld defects can be prevented by the application of beam oscillation which results in stabilized metal flow.(3) In horizontal position, penetration depth is given by the following equation;hp=2.9⋅Ib0.9/υb0.4 Sound full penetration welds can he obtained up to 150 tnm thick carbon steels without front support bars, when proper back beads are produced. It is observed that there is a marked beneficial effect of beam oscillation on prevention of weld defects.(4) In vertical up position, sound full penetration welds can be produced in carbon steels up to 75 mm thickness without front support moulds.