An Investigation of Electron Beam Welding of Sintered Steel (Report 1)

Relation between Welding Conditions and Weld Structure

Abstract

This report shows some experimental data concerning the electron beam welding of sintered steel having various kinds of porosity. The purpose of this investigation is to make clear the relation between the welding conditions and the weld structure, and shrinkage of weld zone of sintered steel. The results obtained in this investigation are summarized as follows:
(1) The pores of sintered steel zone which the electron beam had penetrated, were lost and turned to the solid state when the sintered structure had been melted by beam current. And the different between the structure of weld zone and that of base sintered steel was clearly observed.
(2) It was observed that several cracks which caused lowering the weld strength were created at the boundary of the weld zone owing to the high porosity of sintered steel or due to the high beam current.
(3) The penetrating depth of beam current was enlarged according to increased the beam current and the accelerating voltage, and also the porosity of sintered steel.
(4) The penetrating width of specimen was enlarged according to increased the beam current, however, concerning the accelerating voltage, reverse tendency was observed because the electron beam diameter was pinched due to increased accelerating voltage.
(5) It was observed that some blowhole which caused lowering the strength were created at the melt zone owing to insufficiency of gas exhausing.
(6) In order to prevent for pore creating at weld zone, it is very important that focus position must be placed at the lower side of specimen or use the specimen having a small hole at center to make easy gas exhausting from weld metal.