Accession Number : AD0706375

Title :   THERMAL FATIGUE.

Descriptive Note : Final rept. (Part 2) 1 Jul 66-31 Dec 67,

Corporate Author : TECHNISCHE HOCHSCHULE MUNICH (WEST GERMANY) INSTITUT FUER TECHNISCHE MECHANIK

Personal Author(s) : Neuber,Heinz ; Riege,Hans

Report Date : MAR 1970

Pagination or Media Count : 108

Abstract : Creep and thermal cycling tests with cold-drawn and standard heat treated Nimonic 80A wires were performed at several tensile stress levels. The interrelationships of deformation and fracture behavior under constant and cyclic temperature conditions were investigated quantitatively. The changes of microstructure and of several physical and mechanical material properties, such as electrical resistivity, internal friction and hardness after precreep and thermal precycling have been studied intensively. The acceleration effects of thermal cycling on creep rate and fracture were explained by thermal microstresses arising at the precipitates on account of different coefficients of thermal expansion of matrix and precipitate. A modified creep law is proposed. The effects of cyclic stress superimposed to a constant mean tensile stress on the creep behavior of cold-drawn Nimonic 80A were investigated with tests carried out on a tension testing machine combined with a high temperature furnace. The creep laws under constant and alternating stress conditions were quantitatively compared by a suitable parameter-method. (Author)

Descriptors :   (*NICKEL ALLOYS, *FATIGUE(MECHANICS)), CREEP, THERMAL STRESSES, DEFORMATION, FRACTURE(MECHANICS), HIGH TEMPERATURE, WEST GERMANY

Subject Categories : Metallurgy and Metallography
      Solid State Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE