The influence of a surface quality on measuring mechanical properties with a cylindrical indenter

Abstract

The aim of the work is to develop a new method for yield strength determination of chosen corrosion resistant steels using the micro-indentation measurements. The main advantage of such method is a demand for minimal amount of analyzed material. In the frame of the experiment, the elastic-plastic behavior of special corrosion-resistant - ferritic, martensitic and austenitic - steels was investigated. These steel types are partly suitable for nuclear energetics and also for other fields with high demands on steel quality. The experiment is focused on discovering and defining of such surface quality which would be optimal for maximal yield strength evaluation accuracy determined by micro-indentation measurements, and along with on finding the strengthening trend of the steel types investigated. As the main tool for the evaluation, of the elastic-plastic response, the methodology based on the instrumented penetration test by means of 0.7 mm indenter diameter was chosen. The basic principle of the experiment was comparing evaluated yield strength with help of micro-indenter and those determined by classical tensile test. This paper also deals with FEM simulation of indentation by a flat-ended cylindrical punch into elastic-plastic material with assumed rough contact surfaces. This work shows one of the ways how to include the influence of rough surface into numerical calculation without requiring all asperities of contacting rough surfaces modelled by the finite elements in detail. The influence of the rough surface in combination with the elastic-plastic materials behavior on the shape of the loading curve is subject of this study.