Development of laser welded thin wall stainless steel pipe

摘要

Stainless steel is widely used for architectural materials like roofs, wall panels, etc., because of its high anti-corrosion characteristics. Stainless steel is also used for an ornamental pipe, for example handrails, poles etc. Pipes for ornamental use, appearance and formability are important properties. And thickness of pipe wall is required to be thinner because of its light weight and material cost. For these usage austenitic stainless steel is used in general, but recently high Chromium content ferritic stainless steel is applied to architectural materials because of its low thermal expansion. So thin wall ferritic stainless steel is considered to be used widely in the future.However it is difficult to produce thin wall ferritic stainless steel pipe is difficult to produce by conventional pipe production mills, because of its small t/D and brittleness in weld metal. So we introduce the most suitable method to produce it. The summary is as follows.1) As the forming method for thin wall pipe, "Roll-less forming method" is the most suitable at the point of forming stability under relatively small t/D conditions.2) Good formability, toughness and appearance can be obtained by laser beam welding for ferritic stainless steel.3) The combination of roll-less forming method and laser beam welding is supposed to be advantageous way for the thin wall pipe production.4) Thin wall stainless steel pipes produced by the developed method show good appearance, mechanical properties, formability and anti-corrosion characteristics, therefore developed pipe is suitable for architectural and ornamental materials.