Assertion (A): A mild steel tension specimen subjected to an axial load fails along a surface
at 45° to its axis.
Reason (R): Mild steel is weaker in shear than in tension and the place of maximum shear is at 45° to its axis.
In a mild steel tensile specimen, failure occurs in the form of a cup-and-cone fracture. The
fracture plane is inclined at 45° to the longitudinal axis.
Maximum shear plane is at an angle θ with the normal to the principal plane.
When 2θ = 90°,
θ = 45°
Thus, maximum shear stress acts at 45° to the axis.
Hence, the Reason is also correct, and it is the correct justification for the Assertion
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