Question

A tensile test is carried out on a mild steel specimen of gauge length 40 mm and cross-sectional area 100 mm2. The results obtained for the specimen up to its yield point are given below:

| Load (kN) | 0 | 8 | 19 | 29 | 36 |
| Extension (mm) | 0 | 0.015 | 0.038 | 0.060 | 0.072 |

The maximum load carried by the specimen is 50 kN and its length after fracture is 52 mm. Determine (a) the modulus of elasticity, (b) the ultimate tensile strength, (c) the percentage elongation of the mild steel.

Answer 1

The load/extension graph is shown in Figure

(a) Gradient of straight line is given by:

Young’* modulus of elasticity

= (gradient of graph) (L/A), where

L = 40 mm (gauge length)

= 0.040 m and area

A = 100 mm2 = 100 × 10−6 m2

Young’* modulus of elasticity

(b) Ultimate tensile strength

(c) Percentage elongation