Workability, Densification and Failure Characteristics of Selective Heated Sintered Powder Metallurgy Preforms during Upsetting

Abstract

A study on workability, densification and failure characteristics of porous aluminum–titanium components has been performed by adopting a selective heating method under triaxial stress state condition. The required specimens were made using the powder metallurgy method with 90% of initial relative density and an aspect ratio of 1 through the appropriate compaction pressures. A sequence of upsetting has been executed on the powder metallurgical compacts using a hydraulic press for different titanium compositions (2-6%). In the upsetting process, the damage of the specimens mainly relies on the accumulation of stresses at the damage site. Hence, the damage site of the compacts was identified for various specimens using finite element simulation software. Once the damage position was identified, the compacts were heated at the damage sites (selective heating) for different temperatures, namely 100, 140, 195, 220 and 250 °C using a portable gas cartridge. As a result, the failure initiation is arrested thereby increasing the workability and densification. Selectively heating the damage zone of the components has relieved the accumulated stresses and has reduced the porosity (from 11.385 to 6.702% for Al-2%Ti, from 12.797 to 7.920% for Al-4%Ti and from 13.215 to 8.611% for Al-6%Ti) of the preforms. Thus, the damage limit of the components can be increased during upsetting by the selective heating process.