Performance Evaluation of a Low Cost Creep Testing Machine

Abstract

Mechanical systems and components like steam generators or boilers, nuclear reactors, turbine rotors are operated at very high temperature under significant stress. For this reason, the components and structures need to be designed so that excessive creep distortion must not occur within the expected operating life of the system. Creep is defined as a time-dependent deformation that happens when metals are subjected to constant load at high temperature over a period of time. Knowledge of the creep behavior of metals is therefore important and for this reason Creep testing machines are predominantly used to measure how a given material will perform under constant load, at elevated temperature. This paper aims to study creep properties of various materials being used in high temperature applications through locally made creep testing machine. The basic design of a creep testing machine is the support structure, the loading device, the fixture device (grips and pull rods), and the furnace. The specimen being tested is held in place by the grips and a furnace surrounds the test section and maintains a constant temperature. Maximum applied load on the specimen can be 15 kg and tests could be carried out at maximum temperature of 500°C. Creep curves of strain versus time of aluminum alloy were plotted at a different stress level and temperature. The data are plotted in a simple manner, but analysis easily shows the effect of increased stress due the reduction in specimen cross-section as strain increases. The creep testing machine developed in this work has proven to be satisfactory, cost effective and good alternative to imported creep testing machine.