| 摘要 |
PURPOSE:To reduce a softened area and to improve strength by forcedly cooling a weld zone of maraging steel by an upper cooling jig and a lower cooling jig cooled by low temperature compressed air. CONSTITUTION:The upper cooling jig 4 having void space is mounted on the surface in the vicinity of the weld zone of the single barrel 1 of the maraging steel and the lower cooling dig 5 having void space inside which also serves as back shield is set up on the rear thereof. The compressed air is then introduced into a cooler 7 from a compressed air inlet 6, the cooled air whose temperature is dropped to several tens degrees below zero by adiabatic expansion is fed to the void spaces of the upper cooling jigs 4 and the lower cooling dig 5 to cool these jig 4 and 5 and then, discharged from a compressed air outlet 8. When the single barrel 1 subjected to restraint cooling is TIG-welded to form weld metal 2, welding heat is quickly taken away by the cooled jigs 4 and 5, the cooling time of a heat-affected zone is shortened and as a result, the softened area and hardness reduction are reduced. Consequently, joint efficiency is improved and the weld zone excellent in reducing weight is obtained. |
