Influência da frequência de vibração mecânica sobre o refino de grãos em metais de solda de juntas do aço ASTM A516 Gr.60.

Abstract

The present work had the objective of evaluating the influence of mechanical vibration during the welding process on grain refining in brazing metals obtained in the welding of steel ASTM A516 Gr.60, applied in boilers and pressure vessels. For the mechanical vibration treatment VWC (Vibration Welding Conditioning) process was used.. , The welds were done using the SMAW (Electric Arc with Coated Electrode) and GMAW (Electric Arc Welding with Gaseous Protection) process. AWS ER 70S-6 wire with 1.2 mm of diameter protected with CO2 in the GMAW process and the electrode E7018 with 2.25 mm of diameter in the process SMAW were used as consumable. A vibratory bed was designed and developed to perform the experiments. The joints were performed without and with vibration, subjected to amplitudes ranging from 7.2 to 51.2 m/s2 and frequencies from 205 to 220 Hz. The vibration promoted a better distribution of the microstructure in the weld metal, promoting a refining of up to 113% for an amplitude of 51.2 m/s2 and a frequency of 220 Hz in the GMAW process, in relation to the condition without vibration. In the SMAW process the reduction reached 25% with amplitude 7.2 m/s2 and frequency of 205 Hz. The reductions in the average hardness standard deviations reached 71% for a range of 48.9 m/s2 and a frequency of 215 Hz, in the GMAW process. Using the SMAW process, the mean standard deviation of microhardness value decreased by 27%, with amplitude 7.2 m/s2 and a frequency of 205 Hz, in relation to the condition without vibration.