7 - Vacuum Arc Metal Processing

Abstract

This chapter explains the vacuum arc metallurgical processes, and their industrial implementation. It is mentioned that there are three main practices in modern secondary metallurgy—namely remelting in the vacuum arc furnace, remelting in the electron beam furnace and, finally, refining by the electro-slag remelting process. The vacuum arc remelting (VAR) process is a mature technology for the production of highly qualified materials. Materials for application in the aircraft and aerospace industries are specified by remelting via the VAR process because this technology is proved over several decades and accepted world-wide. With the VAR process, lowest gas contents, excellent oxide cleanliness, extreme low contents of undesired elements, and excellent solidification structure are achieved. In addition with the vacuum arc degassing (VAD) process, the heating of the metal in the ladle can be done under reduced pressure with the effect of predegassing during heating, and prior to the subsequent degassing at a pressure below 100 Pa. VAD overcomes the high heat loss cost of secondary metallurgy by combining several useful operations, degassing and alloying (fine-trimming), into one cycle.