strength is higher than 15 steel, little hardening, no temper brittleness. cold deformation plasticity is high, general for bending, rolling and hammer arch processing, the performance of electric-arc welding and contact welding is good, small thickness when gas welding, easy to crack on the part which is strict in shape or complicated made in shape. the machinability under cold drawn or normalizing condition is better than annealing, general used in the manufacture of parts with low stress and high toughness requirements.