C      Si     Mn      P       S     Ceq

HRB335     0.25 0.80 1.60 0.045 0.045 0.52

HRB400     0.25 0.80 1.60 0.045 0.045  0.54

HRB500    0.25 0.80 1.60 0.045 0.045   0.55

screw-threaded steel