Abstract: There are some issues in the production of sour service pipeline steel, which includes being hard to control carbon, sulfur, phosphorous; high ferrous charge consumption. The root cause was analyzed by thermodynamic calculation combined with production data. The countermeasure was put forward from EAF melting, alloying mechanism, prerefining at EAF tapping, LF refining slag and raw material addition mechanism. After the optimized process was applied, at EAF tapping rephosphorization fraction decreased from 32.3×10^-6 to 6.6×10^-6，carburization fraction decreased from 0.038 % to 0.011 %，desulphurization ratio increased from 27.0 % to 44.1 %; desulphurization ratio in the LF process increased from 84.1 % to 89.5 %, ferrous charge consumption decreased from 1 130 kg/t to 1 070 kg/t, lime consumption decreased from 85.4 kg/t to 33.1 kg/t, aluminum consumption decreased from 2.6 kg/t to 2.1 kg/t, oxygen consumption decreased from 35.1 m³/t to 24.4 m³/t, electricity consumption decreased from 445.8 kWh/t to 422.1 kWh/t, and hence the production cost decreased significantly; the cleanness of liquid steel improved dramatically at LF end, the area ratio of micro inclusion decreased by 29.3 %.

Key words: sour service pipeline steel, steelmaking process, refining slag, ferrous charge consumption, inclusion