TO PERFORM Tensile Testing on STEEL
In this experiment, we basically test the material for its strength. The focus material of this experiment is steel but we can also apply it to other materials like metals and bars made of aluminum. With the help of this test, we derivate material properties like strength, modulus of elasticity, poison ratio, elastic modulus, etc. The Tensile Testing Of STEEL or Tensile TEST ON STEEL (also called bend test) covers the determination of brittle or ductile behavior of steel.(ASTM A615/A615M). This is a standard-based test and we will follow ASTM A615. The test is carried out on a universal testing machine UTM which has a capacity of about 2000 KN.
As we know that the metal especially steel is widely used in the construction of buildings, bridges, culverts, etc so we need to understand its properties and strength. Based on these properties we can then recommend that the material is okay to be used in a structure. One of the most important properties is ductility which is important in steel bars so that the structural member in which steel is being used is also ductile. We know that Brittle materials are not always preferred in Civil structures due to their abrupt behavior of fracture and failure. On the other hand, Ductile materials, give significant safety time before collapsing so that people can escape within time.
This experiment is executed on: Universal Testing Machine also knows as UTM, Test specimen, certain accessories like Bending tables, Supports &Pins, etc.
The UTM used in this experiment has a huge capacity of applying load up to 2000 KN, it has all the necessary attachments and grips used for tensile testing. The test specimen in this experiment will be rebar of a certain diameter upon which we will carry out the experiment.
Tension TEST ON STEEL Procedure
This test is basically the simple one and includes applying load on the specimen in the tensile or tension mode. To do that the test sample is clamped firmly between the grips of the tensile testing machine. Make sure the specimen has a firm grip in the support otherwise it can damage the grips. Follow these steps:
- Take out a test specimen of steel.
- With the help of a suitable tool measure the diameter of the steel rod. For more accuracy take at least three readings and calculate the mean value of the diameter.
- Taking safety precautions, place the test specimen in the tensile test apparatus ( UTM in this case) in such a position that the plane intersecting the longitudinal ribs is parallel to the axis of the pin.
- Using the controller applies force to the test specimen continuously and uniformly throughout the testing operation.
- The material will break at a particular load. Discontinue the application of load when the material is cracked or broke and note down the maximum load taken by the specimen.
- Finally, examine the tension surface of the specimen for cracking with the greatest care and safety.
Observations & Calculations
|S.No||Designation of Steel Bar||Specified Bend Angle|
|1||3 to 11||1800|
|2||14 & 18||900|
Standard bend angles.
|Bar Designation No||Pin Diameter For Bend Test|
|Grade 40||Grade 60||Grade 75|
|3, 4, 5||3 ½ d||3 ½ d||–|
|6||5 d||5 d||5d|
|7, 8||–||5 d||5d|
|9, 10,11||–||7 d||7d|
|14, 18||–||9 d||9 d|
Standard Pin diameters
The diameter of steel rod=……………
Bend angle of given rod=…………
Tensile Strength = Max load taken in tension/ tensile area
- for the given material (steel) Plot the stress-strain graph
- From the stress-strain graph
- Determine Elastic Modulus (E)
Elastic Modulus, (E) = Stress/ Strain
Elastic Modulus, (E) = Slope of Graph
Stress = Load / Cross section Area
Strain (ε) = Change in length / Original length
|Load = 1000 N||Stress= 1000/0.36 = 27 ksi||Diameter of bar = 0.67|
|Strain = 0.004||Elastic Modulus = 27/0.004 = 6,750 ksi||Grade 40|
- Examine the tension surface carefully.
- Do not load the specimen once its specified bend angle is reached.
- The load should be applied uniformly.
Tus the above steel material has the ultimate tensile strength of 27 ksi. For grade 40 this should be at least 40 ksi. For more experiments and lab manuals keep visiting our MOS experiments section.