Easy method for quantitative evaluation of the laser welding process efficiency on austenitic, ferritic, and martensitic stainless steels

For testing the validity of this proposed method many alloys have been studied. So different (autenitic, ferritic and martensitio) stainless steels have been welded by laser technology. Diverse joint geometries as butt, lap and cruciform ones, have been realized. As laser sources 500 W c.w. VALFIVRE / 2 kWc.w. B.O.C./ 1.5 kW c.w. ROFIN SINAR RS 1500 / 6 kW c.w. TRUMPF TLF 3000Turbo and 15 kW c.w. AVCO-EVERETT have been employed for experiments by using two different converging lens types (ZnSe and KCl) / focusing mirrors, two diverse focal length (3.75″ and 5″), two diverse covering gas (He or N2), many working speeds, a 0.5 to 13 kW laser power level range. By the application of this method it has been possible to confirm the idea to leave out of account the knowledge of the thermo-physical parameters of the alloy to be welded. The Melting Area values plotted welding speed values have shown the usual hyperbolic trends. The Welding Efficiency value always plotted versus welding speed range have shown a trend with a maximum one corresponding to the "critical welding speed". The same Welding Efficiency values plotted versus the laser power levels have shown a range values from 20 to 50 mm3kJ for 0.5 to 2 kW and from 30 to 55 mm3/kJ for 3 to 14 kW power level ranges. Finally a schematic layout for using this model has been carried out.