Testing Materials Flashcards
Why test em?
How to ensure fair test
Test to find most appropriate material Fair by: Use same size material Environmental conditions same Same equipment and technique 1 person take all measurements
Simple workshop tests: Tensile Toughness Hardness Malleability and ductility
Tensile - clamp at both ends vertically. Add mass and measure extension. Less deflection is more tensile strength
Toughness - put in vice, hit with hammer. Brittle will bend or shatter.
Hardness - dot punch and hammer. Smaller indent harder material.
Malleability and ductility - bend 90 degrees. Cracks on outside less ductile, cuz crack under stretching
Cracks on inside less malleable, cuz crack under compression
Simple workshop:
Corrosive test
Electrical conductivity test
Thermal conductivity test
Corrosive test - put equal size material outside, exposed to environment for certain time. Inspect for corrosion.
Electrical conductivity test : mark set distance to put multimeter probes, measure resistance.
Thermal conductivity test - use Bunsen, light on one end. Keep distance of Bunsen from 1 end to thermometer at other end, the same. Record time taken for temp to reach set point.
< Time = > conductive
Industrial tests:
Tensile
KW 3
What is measured
TENSOMETER machine.
Standard size test piece held in clamp. Look at diagram.
Worm drive gear mechanism puts under tension.
Load and distance travel plotted, giving info on elastic limit, yeild point, max load and breaking point after necking
Industrial tests
Toughness
KW for name
IZOD IMPACT TEST
Notched test piece held in vice. pendulum set to set position. e absorbed by impact calculated by amount that it swings after impact.
Industrial test
Hardness
3 main
ROCKWELL- Preload applied using diamond indenter, breaks through surface. This makes 0 reference point. Additional load applied for X time. This is released and distance between preload and applied load measured.
BRINELL - standard size ball forced into surface using preset load. Diameter of dent measured
VICKERS PYRAMID - used for very hard materials . Diamond square based indenter used. Microscope measures size of indent
NDT
What is it carried out on
Why
2 main examples
Non destructive testing Carried out on p. Not material. Used to find defects in material 1 - Ultrasonic sound waves find faults 2 - X rays find tiny hairline cracks
Industrial
Malleability & ductility
KW
Bend test
Tests how well it withstands cracking during 1 continuous bend.
Test piece put in machine. A mandrel loads test piece at center and bends to predetermined angle or until fractures.
Ductile material will have plastic deformation prior to failure.
Industrial
Corrosion
Conductivity - thermal and electrical
Corrosion - same as workshop but is done in lab with controlled and simulated environment.
Thermal conductivity - uses heat flow meter . Square shape material places between 2 temp controlled plates. Temp increased at constant rate, and heat flow through it is measured by heat flow sensor on surface.
Electrical - same as workshop
