Abstract
Classifying weldability in the five classes, the authors made weldability tests on low manganese high tensile-strength steels and found the following reuslts.
(1) It is recognized in each steel-plates under test that the close-relation respectively exists among Ceq, hardness in the vicinity of water-quenched end in Jominy test, max. hardness of heat-affected zone during welding, and bead-bend angles. When Ceq is located above 0.5%, weldability is apt remarkably to become worse.
(2) The higher welding current, the lower welding speed, max hardness at the heat-affected zone is decreased and bend angle is increased propotionally. In the case of hardness below 300Hv, no measurable differences of bend angles are exhibited.
(3) Using the low-hydrogen type electrode, satisfactory results are obtained in weldability.
(4) With regard to influence upon elapsing time for bend angle of longitudial bead-bend test after welding, bend angle is found to be very small immediately after welding, in spite of various type of electrodes. When the low-hydrogen type electrode is used, bend angle is rapidly increased within following 24 hrs. However, the high cellulose type electrode is sluggish, concering increase in bend angle as compared with the former. It may be assumed that causes as above are due to effect of both hydrogen content absorbed during welding and residual hydrogen content retained after welding.
