Flashcards in Examination and Testing Deck (15)
After removal of a load the strain, the specimen returns to its original length, the material under test is said to be elastic.
Ductility is the property of a material which allows deformation to occur without fracture. It is the ability of the material to be formed cold without fracture.
Hardness is the property of a material which enables it to resist deformation and penetration, (and therefore is an important property of material). Hard materials offer high resistance to forming and machining methods. Three common methods of testing for hardness are the: Vickers Test; Brinell Test; Rockwell Test
Explain mechanical properties.
A mechanical property is the material's ability to resist or withstand a particular kind of physical force.
Explain Yield point
The yield point is the point at which the material first acquires permanent deformation. In the specifications of steel the yield point is usually given.
Explain tensile strength
The maximum stress that the specimen will stand before fracture.
What are the 3 main types of destructive testing?
* Chemical testing.
Name 8 types of destructive testing.
* tensile test.
* Bend test.
* Impact test.
* Macroscopic test.
* Hardness Test.
* Fillet Test.
* Nick break test.
* Chemical analysis test.
Explain Nick break.
•Examines internal qualities.
•Small saw cut made in ends of a section of metal cut from weld.
•Section broken under a press.
•Shows lack of penetration, porosity, slag inclusions.
•Used on butt joints.
Explain bend test.
•Types of bend tests
•Can be either Face, Root or Side bends.
•To examine the soundness and ductility of the joint at the weld zone.
•Requirements – on completion of test no crack or defect greater than 3 mm
Explain Macro test.
•A saw cut is made to produce a cross-section of the weld.
•This cross-section is polished to remove all scratches.
•The sample is then etched in an acid solution.
•This type of examination allows us to see:
•the depth of penetration
•alignment of joint parts
•heat affected zone.
Explain Tensile Test.
•Tests indicate resistance to tensile load and ductility
•Weld strength shall be equal to specified minimum tensile strength of plate
•All weld tensile
•shall be not less than 95% specified minimum tensile strength of plate
•Tests are carried out on sample test coupons cut from welds.
•A sample is machined from the test coupon.
•The machine sample is placed in the tensile tester and subjected to a load which pulls the sample apart.
•This allows is to determine:
•ultimate tensile strength of the weld
•fracture strength of the weld
•yield strength of the weld
•elongation of the weld.
•These tests allow us to see if an electrode or wire will stand up to calculated structure loadings.
Explain Impact test.
•Tests the metals resistance to sudden impact load.
•The energy absorbed by the specimen in the weld metal or the heat – affected zone is determined. (toughness ).
Explain hardness test.
•Hardness is a materials resistance to
•Types of hardness tests
•Uses a steel ball bearing of 10mm diameter.
•Pressed into the surface with a load of 3000kg.
•The diameter of the impression is measured with a special microscope and is converted using a table.
•Penetrated by a diamond cone into the metal using 150 kg.
•Depth of impression is indicated on a dial.
•Uses a square based diamond point.
•Pressed into the surface at a pre-determined load.
•Maintained for a set period of time and released automatically.
•Measurement are taken across the diagonals under a microscope and referred to a table.