Development and evaluation of a novel inclusion seeding methodology for Ti−6Al−4V castings

Abstract

Hard alpha inclusions in titanium (Ti) investment castings are generally known to have detrimental effects on the mechanical properties of these castings. However, actual inclusions are infrequent and occur in random locations in castings. As a result, it is difficult to obtain tensile or fatigue test specimens of titanium castings with inclusions in the gage section. Quantifying the adverse influence of inclusions on the mechanical properties of castings is, therefore, extremely challenging. To address this problem, a novel artificial inclusion seeding methodology was developed to emulate actual Ti investment casting inclusions. Prefabricated inclusions were seeded into machined holes in cast Ti-6Al-4V plates, the holes were back-filled with plugs of the same Ti alloy and were then electron-beam (EB) welded closed. Hot isostatic pressing (HIP) was utilized to incorporate the inclusions fully into the cast titanium material. Finally, the plates were machined to create mechanical test specimens with inclusions centered in the gage region. Test specimens created by means of this novel artificial seeding methodology were evaluated and found to be equivalent to Ti casting specimens containing actual cast-in inclusions.

Analysis and Prevention of Dent Defects Formed during Strip Casting of Twin-Induced Plasticity Steels

“…[8][9][10] However, they face many problems arising from hot rolling, such as decreased production yield by grain-boundary oxidization during reheating, generation of microscabs on the surface by selective oxidization due to excessive containment of Al and Mn in the steel, [11,12] and crack initiation during hot rolling of slabs. Therefore, these problems are expected to be solved by applying the strip-casting process to TWIP steels, which eliminates the hot-rolling step.…”