Explain the strain-hardening phenomenon on the basis of dislocation - dislocation strain field interactions. also, briefly describe what generally happens to the ductility of a metal that has been strain hardened (i. e. does strain hardening make a metal more ductile or

Ahelical coil spring has a mean diameter of 50 mm, a wire diameter of 5.5 mm and is wound with a pitch of 10 mm. the spring steel has an ultimate strength of 1250 mpa. find the force needed to compress the spring solid and the wire stress in this condition. state whether the spring will return to its initial length.