جوشکاری لیزر CP Ti به فولاد زنگ‌نزن با شکل‌های ضربان زمانی مختلف

Laser welding of CP Ti to stainless steel with

different temporal pulse shapes

جوشکاری لیزر CP Ti به فولاد زنگ‌نزن با شکل‌های ضربان زمانی مختلف

ABSTRACT

CP Ti and stainless steel sheets were laser welded by using a pulsed wave Nd:YAG laser welding system. The effect of pulse profiles used in laser welding was studied by investigating weld appearance, weld geometry, microstructure, hardness variation, joint strength and failure mode of welds. Weld quality was strongly affected by the temporal pulse profile adopted in laser welding. In comparison with the use of a normal rectangular pulse profile, stronger welds with a better homogeneity and a complex fracture mode were achieved by using a ramp-down pulse profile. This quality enhancement was contributed from the less degree of intermixing between two welding materials in melting pools.

 

جوشکاری آلیاژ Al–Cu–Mg–Mn به روش تیگ

Effect of welding parameters on the solidification microstructure

of autogenous TIG welds in an Al–Cu–Mg–Mn alloy

تاثیر پارامترهای جوشکاری بر میکروساختار انجمادی جوش های TIG

بدون ماده پر کننده در یک آلیاژ Al–Cu–Mg–Mn

ABSTRACT

The weld metal microstructures of autogenous TIG welds have been investigated for a range of welding conditions using an Al–Cu–Mg–Mn alloy. It was found that a combination of high welding speeds and low power densities provide the thermal conditions required for the nucleation and growth of equiaxed grains in the weld pool, providing heterogeneous nucleation sites are available. The most likely origin of the nucleants is from a combination of dendrite fragments and TiB2 particles that survive in the weld pool. The finest microstructure was observed in the centre of the weld and is attributed to the higher cooling rates which operate along the weld centreline. Composition profiles across the dendrite side arms were measured in the TEM and were found to follow a Scheil type segregation behaviour where there is negligible back diffusion in the solid. The measured core concentration of the dendrite side arms was found to rise with increasing welding speed and was attributed to the formation of significant undercoolings ahead of the primary dendrite tip, which enriched the liquid surrounding the dendrite side arms.