Process of tension test on steel
Tension test is conducted on mild steel, tor steel and high tensile steel to find out different characteristics like Young?s modulus, ultimate strength, and the percentage elongation. Under this type of test, a steel rod is susceptible to tension load with the use of a Universal testing machine(UTM).
The following equipments are used for conducting Tension Test on Steel:
1. Universal Testing Machine(UTM)
3. Scale Vernier Calipers
4. Punching tools
Method for Tension Test on Steel Rod
1. Arrangement of Specimen: In the beginning, the steel rod specimen is cleaned and gauge length is marked on it. The gauge length is measured with the formula . A punching tool is used to mark the gauge length on the specimen.
2. Range Calculation: A tensile stress value is presumed, based on which the maximum predictable load strength of the rod is worked out. After obtaining the load strength, the range is measured and this range is placed in the UTM.
Assuming working stress = 140N/mm2
Factor of safety = 3.
i.e Ultimate stress = 140?3 = 420N/mm2.
Ultimate load = 420 x area of c\s.
Out of this ultimate load, applicable range should be determined.
3. Positioning the Specimen: The handle is operated in order that the specimen tightly sets to the top base. The left valve is retained in a fully closed position and the right valve in a normal open position. Open the right valve and close it after the lower table is lifted a little. Correct the load pointer to zero with the zero adjusting knobs. By operating the handle, raise the lower crosshead chuck up and tightly grip the lower part of the specimen. As soon as the specimen is arranged, the jaws are locked.
4. Placing Extensometer: Set the extensometer on the specimen as well as the reading to zero.
5. Load Application: Revolve the right control valve slowly to open position to obtain the required loading rate. When the specimen is under load, gradually unclamp the locking handle. Record the extension at an agreeable load increment. Extensometer should be eliminated prior to attain the yield point. The proper valve should be utilized to employ the load and the left valve should be utilized to deliver the load on the specimen.
6. Vital Load Points: With the surge in load at some point, the load pointer remains stationary. Based on this, the load points to the yield point. With further surge in load, the pointer goes backward and specimen ruptures. The load prior to this breaking refers to the ultimate load. The load at the breaking of the specimen is known as the breaking load.