Al plated welded pipe for hardening use and al plated hollow member and method for producing same

A method for producing an Al plated hollow member comprising:

• a heating step of heating by a heating temperature of 850° C. or more an Al plated electric resistance welded steel pipe for hardening use comprising a base material made of a tubular steel plate and an electric resistance welded zone provided at a seam portion of the steel plate and extending in a longitudinal direction of the steel plate, wherein
• the base material contains, by mass %,
• C:
• 0.06 to 0.50%,
• Si:
• 0.01 to 0.80%,
• Mn:
• 0.60 to 3.00%,
• P:
• 0.050% or less,
• S:
• 0.050% or less,
• Al:
• 0.10% or less,
• O:
• 0.006% or less,
• N:
• 0.020% or less,
• Ti:
• 0.01 to 0.10%,
• B:
• 0 to 0.1000%,
• Nb:
• 0 to 0.10%,
• V:
• 0 to 0.30%,
• Cr:
• 0 to 0.50%,
• Mo:
• 0 to 0.50%,
• Ni:
• 0 to 0.50%,
• Cu:
• 0 to 0.50%,
• Ca:
• 0. to 0.005%,
• REM:
• 0 to 0.005% and
• a balance of Fe and impurities, and
• the base material is further provided with
• an intermetallic compound layer positioned on the surface of the steel plate and including an Al—Fe—Si-based intermetallic compound and
• an Al plating layer positioned on the surface of the intermetallic compound layer and containing Al and Si;
• a forming step of forming the heated Al plated electric resistance welded steel pipe for hardening use into a desired shape;
• and
• a rapid cooling step of rapid cooling the Al plated electric resistance welded steel pipe for hardening use formed into the desired shape by an average cooling rate of 20° C./s or more, wherein
• the following formula (1) and formula (2) are satisfied, wherein X (μm) is a thickness of the intermetallic compound layer, Y (μm) is a thickness of the Al plating layer, t (mm) is a pipe thickness of the steel pipe, D (mm) is an outside diameter of the steel pipe, and HR (° C./s) is an average rate of temperature rise from ordinary temperature to a peak temperature −50° C. set at the time of hot forming:
• Y/X≥α×t/D (1)
• α=168×HR−0.45 (2).