A hot rolled steel shaft is subjected to a torsional load that varies from 300 kNmm clockwise to 100 kNmm anticlockwise as an applied bending moment at a critical section varies from +400 kNmm to -200 kNmm. The shaft is of uniform cross section and no key-way is present at the critical section. Determine the required shaft diameter by taking factor of safety 1.5. For the material, take ultimate tensile stress as 560 MPa, stress at yield point 420 MPa design stress is 280 MPa. Also take the modification factor as 0.62, size correction factor as 0.85, the load factor for bending as 1 and the load factor for torsion as 0.58.