Assessment of parameters variations for treatment of CO2 laser carburizing over AISI 4340 steel

Renato Araujo Barros¹; Jean Denape²; Karl Delbé³; Antônio Jorge Abdalla⁴; Humberto Lopes Rodrigues⁵; Renann Pereira Gama⁶

¹ UNESP/ ENIT - INP; ² ENIT- INP; ³ ENIT - INP; ⁴ IEAv- CTA; ⁵ FATEC Pindamonhangaba; ⁶ UNESP

doi:10.20906/CPS/COB-2015-0260

Resumo

This study evaluated the best parameters for the carburizing treatment using a CO2 laser of low power (125 W) over an AISI 4340 steel previously subjected to heat treatments of quenching and tempering. The varied parameters of CO2 laser were speed and resolution (number of passes). The power was kept constant at 125 W and the coating used was carbon black. In addition, the range of speed was from 1200 to 2000 m/s, with a resolution of 600 dpi (dots per inch). After treatment, metallographic preparation and optical microscopy observation were performed (Fig. 1), in addition to the evaluation of parameter variations through hardness measurements and microscratch tests (Fig. 2). It is possible to observe through the microscopic images that the laser treatment performed at a speed of 2000 m/s provided a better homogeneity for the coated zone (CZ) than the treatment carried out at a speed of 1200 m/s.

Palavras-chave: AISI 4340 steel; surface treatments; laser carburizing; microscratch tests