Method for manufacturing surface treated steel material using a chemical conversion treatment liquid

摘要

A method of manufacturing a surface treated oil well pipe comprising performing chemical conversion treatment on an oil well pipe having a steel composition containing 0.5-13% Cr using a chemical conversion treatment liquid containing zinc and phosphoric acid or manganese and phosphoric acid and further containing potassium tetraborate to form a chemical conversion film of a zinc-phosphate type or a manganese phosphate type, wherein the chemical conversion treatment is carried out in the absence of fluoride ions.