3 - Methods for testing materials - Industrial tests Flashcards
Tensile strength test
Tensometer machine
Standard test piece held with a clamp at each end
One clamp is fixed, one moves away from the fixed one, putting the material under tension
The distance stretched is plotted, and information about maximum load, breaking point, yield point and elastic limit are measured
Toughness test
Izod impact test
Notched test piece held vertically in the vice
Pendulum released from set position and swings to hit the test piece
Energy absorbed by the test piece is calculated from the height the pendulum reaches after hitting the test piece
Material that absorbs the most impact is the toughest (gives the smallest pendulum swing)
Brittle material absorbs less energy and the pendulum swings further
What are the three hardness tests?
Rockwell test
Brinell test
Vickers pyramid test
Rockwell test
Preload applied to the material with a diamond indenter.
Preload is the ‘datum’ or zero reference
Additional LARGER load is applied and held for a predetermined amount of time (dwell time)
Load is released and the distance between the applied load and the preload is measured
Brinell test
Standard sized steel ball forced into the surface of the material using a pre-set load.
Diameter of the indent on the surface is measured.
Vickers pyramid test
Only used for very hard materials.
Uses a diamond square based pyramid to intent materials surface
Microscope is used to measure the size of the indent
Malleability (and ductility) test
Bend test
Test piece is held in a bending machine, supported at both ends
Test piece is bent until it reaches the predetermined angle or until it fractures, it is then inspected
Cracks on the OUTER BEND indicate the level of ductility
Cracks on the INSIDE BEND indicate the level of malleability
Corrosion
Similar to workshop test for corrosion except lab conditions are used to create the environmental effects.
Materials then inspected for surface corrosion
Electrical conductivity
Collect material samples of the same dimensions.
On the surface mark a set distance at each end
Place a multimeter probe on each mark
Measure the resistance
Higher resistance indicates lower conductivity
Thermal conductivity
Heat flow meter used
Square shaped material sample placed between two temperature controlled plates
Temperature increases, and the heat flow through the material is measured by heat flow sensors placed on the material’s surface
As the material is heated to a certain temperature, the sensors measure and record thermal conductivity
