Steel for X80-grade tube bundle outer bearing tube and production method thereof

The steel comprises the following chemical components in percentage by weight: 0.13 percent to 0.17 percent of C, 0.20 percent to 0.40 percent of Si, 1.75 percent to 2.00 percent of Mn, 0.003 percent to 0.012 percent of P, less than or equal to 0.002 percent of S, 0.01 percent to 0.04 percent of Al, 0.040 percent to 0.060 percent of V, 0.08 percent to 0.25 percent of Mo, 0.045 percent to 0.07 percent of Nb, 0.01 percent to 0.02 percent of Ti, 0.35 percent to 0.45 percent of Ni, 0.15 percent to 0.25 percent of Cu, 0.004 percent to 0.009 percent of Ca, 0.06 percent to 0.08 percent of RE, less than or equal to 0.00015 percent of H, less than or equal to 0.0020 percent of O and the balance of Fe and inevitable impurities, wherein Ca/S is more than or equal to 1.8. The yield strength of the steel for the bearing pipe outside the pipe bundle ranges from 555 MPa to 600 MPa, the tensile strength ranges from 625 MPa to 690 MPa, and the ductility ranges from 23% to 28%; the impact absorbing energy at-20 DEG C is 160-22