Book Description

Numerous industrial users were asked for their appraisal of vacuum-degassed steel. Their responses regarding the merits of this vacuum treatment were varied. The producers and users of large forgings reported fewer internal defects, improved toughness, and decreased processing time through shorter hydrogen relief treatments. Improved fatigue life in applications such as bearings was attributed to fewer and smaller nonmetallic inclusions in vacuum-degassed steel. The users of medium and small forgings reported only marginal improvement in properties and little or no change in rejection rates by nondestructive testing. Unfortunately, many of the users could not give a meaningful evaluation because they knew that frequently their suppliers filled orders with vacuum-degassed steels even though such treatment was not specified. Consequently, these users are unable to separate the air melted and the vacuum-degassed steels in their stock for comparison. A more comprehensive study of fully identified steels, steelmaking practice, degassing methods, material properties, and performance in service will be required before a satisfactory evaluation of the merits of vacuum-degassed steels can be made. (Author).