Creep of high-purity nickel

Abstract

,~ study was made of t he creep behavior in tensio n at 300 0 700 0 900 0 and 1 200 0 F of initi, !I y annealed high-purity nickeL Discontinuous flow was dbsel' v~d in ~ach of' the three stages of creep, and. it was affected by ~e mperatu~'e, s train rate, and prior-strain hi stor y. Th e phenomenon of s tram aglllg was especially promlll ent at 300 0 F as manifested by t he attainment of an appreciable creep life in specimens stressed in excess of the te ns ile streno-th at this temperatur~. The experimentall'esults are analyzed in terms of t he past and prese~ t theories of deformat IOn of metals. Stralll hardenlllg, recovery, and t he initiation , propagation , and types of fractures obtamed dunng creep are further evaluated by means of true-stress-true-strain and hardness data obtained at room temperature and by metallographic examination of the fractured specimens.