COLD-ROLLED STEEL SHEET SUPERIOR IN CHEMICAL CONVERSION TREATMENT PROPERTY AND GALLING RESISTANCE, AND MANUFACTURING METHOD THEREFOR

摘要

PROBLEM TO BE SOLVED: To provide a high-strength cold-rolled steel sheet containing Si, which has both of excellent chemical conversion treatment properties and galling resistance. SOLUTION: This manufacturing method comprises the steps of: forming an Mn-containing film (excluding a phosphate film) on the surface of the cold-rolled steel sheet containing 0.1 mass% or more Si; and annealing the treated cold-rolled steel sheet. The Mn-containing film (excluding the phosphate film) contains Mn of 0.5 to 5,000 mg/m2. The steel sheet contains 0.3 mass% or more Si and contains Mn so as to satisfy the expression; Si content/Mn content≥0.4. COPYRIGHT: (C)2007,JPO&INPIT