Mechanical Testing  Uniaxial tension test  Hardness testing

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

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

9000 Al Maraging Steel 8000 7000 Load (N) 6000 5000 4000 3000 2000 1000 0 0 1 2 3 4 5 Stroke (mm) 6 300 Teflon Teflon 250 Load (N) 200 150 100 50 0 Data courtesy: Prof. Shashank Shekhar 0 10 20 30 40 50 Stroke (mm) 60 70 80 90

0 10 20 30 40 50 60 70 80 90 9000 300 8000 250 7000 Maraging Teflon refered to secondary x and y axis Load (N) 6000 200 5000 150 4000 3000 100 A 2000 Al Maraging Steel Teflon 1000 50 0 0 0 1 2 3 Stroke (mm) 4 5 6

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”.