30 Process for Manufacturing non-heat treated highly elongated 30kg hydroforming pipe and tube

摘要

PURPOSE: A process for manufacturing a non-heat treated highly elongated 30kg hydroforming pipe and tube is provided to give uniform elongation higher than 20% to the welded part of a hydroforming pipe and tube. CONSTITUTION: In a manufacturing method of non-heat treated highly elongated 30kg hydroforming pipe and tube comprising C 0.002-0.005wt.%, Mn 0.05-0.20wt.%, P 0.02wt.% or less, S 0.015wt.% or less, Al 0.02-0.04wt.%, Ti 0.03-0.5wt.%, balance of Fe and other inevitable impurities, tubing process is conducted at a reduced rate of 20 to 60mpm while clearance gap of squeeze roll for compressing both edge parts of reheated steel sheet to be processed is adjusted such that it is possible to minimize process-hardening that leads to elongation decrease in the steel sheet. In this method, the clearance gap between both side rolls(2) is adjusted to be less than 2mm, and the clearance gap between side roll and top roll(3) is adjusted to be less than 1mm.