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日本NKK在大直径焊管机上(最大直径25英寸)采用25kw高功率激光焊接,这在世界尚属首创.新焊接法速度快(对于板厚10mm的焊速为10m/min)生产率高,同时可保证焊接部位的质量和母材相当.一般焊接法在确保钢管的性能和生产率方面是相矛盾的.例如,TIG(钨极惰性气体保护焊)、TIG加等离子焊接及SAW(埋弧焊)等熔融焊接法的焊接性能好,但是生产率低,而ERW(电阻焊)及BW(锻接)等压焊法的生产率高,但是焊接性能差,产品用途有限.激光束能量密度高,热输入小可高速焊接,而不产生电子束那样的X射线,近年用它代替TIG法或等离子体焊接法.但是,由于受激光输出功率和稳定性的制约,该公司也只采用5kW级的小容量焊接机在小直径薄壁管(主要生产汽车排气用不锈钢管)的作业线上进行实验.此次,采用25kW激光焊接机成为可能的原因:①由于高功率激光的进步,使其能解决熔融焊接生产率低的问题(NKK公司采用在ERW工序进行预热和激光焊接相组合的技术.而实现高速焊接);②激光束热源具有高密度能、热输入小的特点,使氧化物微细分散(尺寸约为母材部分的十分之一),而且可以防止熔融焊接时热影响部位质量劣化的问题,激光焊接并起热处理作用,使焊接部位的性能和母材相当.
Japan NKK 25kw high-power laser welding on a large-diameter pipe machine (up to 25 inches in diameter) is the first of its kind in the world.New welding speed is high (10m / min welding speed for 10mm thickness) Welding quality is guaranteed to be comparable to that of base metal.General welding methods are conflicting in terms of ensuring the performance and productivity of the steel pipe, such as TIG (TIG welding), TIG plasma welding and SAW (Submerged Arc Welding) Fusion welding has good weldability but low productivity, while ERW (Weld Resistance) and BW (forging) are high productivity but poor weldability and limited product use. Laser beams have high energy density and small heat input Can be welded at high speed without generating X-rays such as electron beams, and in recent years it has been used instead of the TIG method or the plasma welding method. However, due to the limitation of laser output power and stability, the company uses only a small capacity of 5kW The experiment was conducted on a small-diameter thin-walled tube (a stainless steel tube for producing automobile exhaust gas), which is why the 25kW laser welding machine is possible: (1) the high-power laser can solve the problem of melting Welding production (NKK uses a combination of preheating and laser welding in the ERW process to achieve high speed soldering); (2) The laser beam heat source has the characteristics of high density energy and small heat input, so that the oxide is finely dispersed One tenth of the base metal part) and can prevent the problem of heat-affected parts quality deterioration during the fusion welding. The laser welding and the heat treatment function make the performance of the welding part equivalent to that of the base metal.