The effects of hydrostatic pressure on the ductility of metals and alloys

✍ Scribed by M. Yajima; M. Ishii; M. Kobayashi

• Publisher: Springer Netherlands
• Year: 1970
• Tongue: English
• Weight: 754 KB
• Volume: 6
• Category: Article
• ISSN: 1573-2673
• DOI: 10.1007/bf00189821

✦ Synopsis

A law governing the change in the ductility of metals and alloys under pressure is given:

where P is the hydrostatic pressure, elo¢,1 is the strain accumulated from the start of necking to fracture, f, necking stress and (df/ds) the coefficient of linear work hardening. This relation is derived from a newly proposed criterion of ductile fracture, viz. "constancy of hydrostatic tensile stress", which indicates that the change of ductility with pressure obeys a three halves power law. The observed increase in ductility of widely differing metals and alloys under pressure up to 10,000 kg/cm z has confirmed that the proposed criterion is acceptable.

It is further shown that the ductilities of some copper alloys with low stacking fault energy, such as Cu Zn and Cu-Ge alloys, increases with pressure at the beginning but the increase stops at fairly low pressure, i.e. 3,500 ~ 4,000 kg/cm 2, and their ductilities become almost insensitive to the pressure applied. It is suggested that ductile fracture of metals with low stacking fault energy is dominated by a process which occurs not by the hydrostatic stress component but by shear stress only.