Patent ID: 8071516

Claim:
A lubricant for use in press forming of a high tensile strength steel sheet, comprising: a lubricant base, and additives added to the lubricant base, the additives comprising (a) a sulfuric extreme pressure agent, (b) a rust inhibitive agent, and (c) a highly basic calcium sulfonate wherein content of sulfur contained in the sulfuric extreme pressure agent is not less than 2 wt % of total weight of the lubricant and not greater than 15 wt % of total weight of the lubricant, wherein content of the rust inhibitive agent is not less than 1 wt % of total weight of the lubricant and not greater than 10 wt % of total weight of the lubricant, wherein the content of calcium in the highly-basic calcium sulfonate is not less than 0.2 wt % of the total weight of the lubricant and not greater than 10 wt % of the total weight of the lubricant; the highly-basic calcium sulfonate has a base value of 300 mg KOH/g or more; the sulfuric extreme pressure agent comprises one or more polysulfides, one or more sulfurized fats, and zinc dialkyldithiophosphate (ZnDTP); the rust inhibitive agent comprises one or more barium sulfonates, one or more oxidized wax compounds, one or more calcium sulfonates having a base values less than the highly-basic calcium sulfonate, and one or more metallic soaps of lanolin; and the lubricant has a kinetic viscosity of not less than 50 mm 2 /s at 40Â° C. and not greater than 200 mm 2 /s at 40Â° C.