MANUFACTURE OF ALLOY STEEL INGOT BY ELECTRON BEAM MELTING

摘要

PURPOSE:To reduce flaws on the surface of an ingot, in the method for the electron beam melting of an alloy steel in which the amt. of components to be evaporated is regulated to =2%, by specifying for discharging the ingot. CONSTITUTION:The position of the surface of a molten pool is held to = 30mm from the upper end of a mold, an ingot is raised to 1mm maximum within 5sec and is thereafter lowered, and the amt. of the ingot to be drawn per time is regulated to = 10mm. For facilitating the involving of vapor-depositions sticking to the inner wall of the mold, the time required for drawing per time is regulated to = 5sec. By regulating the amt. of the ingot to be drawn per time to = 10mm, flaws on the surface of the ingot can be reduced. For example, at the time of manufacturing an ingot of 300mmPHI, in the case the amt. of the ingot to be drawn per time is regulated to 5mm, the maximum depth of flaws on the surface is rapidly reduced by regulating the distance from the upper end of the mold to the surface of the molten pool to = 30mm. Further more, flaws on the surface of the ingot can be reduced by regulating the initial amt. of the ingot to be raised to = 1mm.