Chapt 1 Flashcards
(33 cards)
What is the formula for gauge length?
5.65 root original cross-section area or 5D (diameter of cross-section area)
What are the 3 phases during the tensile test
Elastic Deformation, Uniform plastic deformation, necking(
What is the highest point of the linear point called?
Elastic Limit
What is the stress that occurs slightly after the elastic limit? What is the lowest point of the stress called?
Yield stress and Yield point
What is the definition of UTS and whats the formula?
Ability to resist tensile force without rupture, UTS= Max Force/Original cross-section area (kN/mm^2 or N/mm^2)
What is the definition of yield stress and whats the formula?
Yield stress is the stress required to start plastic deformation. Yield stress = force at yield point/original cross-section area
What is %E and %A and what do they measure? Whats the formula?
Elongation and are reduction, both measurements indicate the ductility of the material.
For E%,(Lu-Lo)/Lo x 100%
For A% (Ao-Au)/Ao x 100%
u-final
o-original
What is proof stress? How do you find it?
Proof stress is for materials that do not have a yield point.
Calculate the given proof stress by multiplying it by the gauge length.
Mark out the extension
Draw a parallel line till it intercepts the graph and thats your proof force
Proof force/Original cross-section area = Proof stress
What does young modulus measure? Whats the formula?
Young modulus measures the stiffness of the material, the formula is stress/strain
Stress=Force/Original cross-section area
Strain=Extension/Gauge Length
What is the relation between all the properties?
(Clue:S,H,D,B,T,WR,M)
When strength increases,
Hardness, brittleness, wear resistance also increase,
Ductility, machinability and toughness will decrease
STIFFNESS IS AN INDEPENDENT PROPERTY IT IS NOT AFFECTED BY THE REST
What is the definition of hardness?
measure resistance to indentation, plastic deformation and abrasian
What are the types of hardness test?
Brinell Hardness Test, Vickers Hardness Test and Rockwell Hardness Test
What is the indentor used in brinell hardness test?
Hardened steel ball indentor
What is the thickness of the samples for soft and hard materials?
15x the depth of penetration for soft materials
7x the depth of penetration for hard materials
Write out the table with the HBN F/D^2 Indentor diamter and load on a paper now
Steel and Cast iron, >100 HBN 30F/D^2 2.5mm 187.5kgf
Aluminium alloy, copper 30-200 HBN 10 F/D^2 2.5mm 62.5kgf
1kgf=9.8N
List the advantages and disadvantages of BHT
(+)
-close relation to tensile strength, 3HBN=UTS
-only one scale of hardness
(-)
-indentor will be damaged against materials harder than hardened steel
Advantages and Disadvantages of Vickers hardness test
(+)
-More accurate than brinell hardness test
-Negligible surface damage
-Can be used for hard and soft materials
-Suitable for precision of thin sheets
(-)
-Expensive
-More preparation work when executing
What is the indentor used for Vickers Hardness Test?
Square based diamond pyramid indentor
What does rockwell hardness test measure?
Depth of impression
What is the use of minor load
To eliminate errors caused by surface irregularities
Or
Take away the slackness in the system
Advantages and disadvantages of RHT
(+)
-rapid in action
-suitable for hard and soft materials
-wide range of scale
(-)
-too many scales
-cannot be used for any thin sheets and foils
-not reliable as VHT
List out the minor load, major load, indentor used and applications for HRB,HRC,HRA
Look at notes i lazy
Impact test are used to?
Indicate toughness
Indicate brittleness
Effect of temperature on toughness
Difference between charpy and izod impact test
Charpy:
-two ends of test piece is supported
-striker hits the centre with the notch facing away from it
Izod:
-1 end is held
-striker hits the other end with the notch facing towards it
