Anandh Subramaniam & Kantesh Balani Mechanical Testing Uniaxial tension test Hardness testing Impact testing Fatigue testing Creep testing MATERIALS SCIENCE & ENGINEERING Anandh Subramaniam & Kantesh Balani Materials Science and Engineering (MSE) Indian Institute of Technology, Kanpur- 208016 Email: anandh@iitk.ac.in, URL: home.iitk.ac.in/~anandh AN INTRODUCTORY E-BOOK Part of http://home.iitk.ac.in/~anandh/E-book.htm A Learner’s Guide Advanced Reading A E

Variables/parameters in mechanical testing Process parameters (characterized by parameters inside the sample)  Mode of deformation, Sample dimensions, Stress, Strain, Strain Rate, Temperature etc. Material parameters  Crystal structure, Composition, Grain size, dislocation density, etc.

20 18 stress stn dig for al steel and rubber

Data courtesy: Prof. Shashank Shekhar

Hardness Test Hardness tests are perhaps the most easy to conduct and most difficult to interpret (i.e. correlate with other well understood mechanical properties like yield strength & UTS). With the advent of micro/nano-indentation the utility of hardness tests have increased considerably and useful information, way beyond the traditional scope can be obtained. Broadly there are three kinds of hardness tests (names are in brackets): (i) those which measure resistance to indentation (Vickers, Knoop, Rockwell) (ii) those which measure resistance to scratching (Mohs) (iii) those which measure ability to rebound a indenter (Shore Scleroscope). The common one used by materials scientists is the one which measures “resistance to indentation”.