Isarawit Chaopanich, Jitti Buapoon, Sirichai Wanavimolkul, Krisda Harnsombat, Supapol Oupanant, Sompong Tiasakul, Sakarin Bowngern and Tinnaphop Poolkhaolan

pp. 361 - 367

Abstract

The objective of this research work was to study the effects of laser welding when compared with shield metal arc
welding (SMAW) process on the heat input, welded deposit rate, residual stress, distortion, microstructure and micro
hardness. The martensitic stainless steel grade 431 specimens were overlay welded with the stainless steel filler metals. From
the results, the heat input of 0.26 kJ/mm in laser welding calculated was significantly lower than that of 1.66 kJ/mm in SMAW,
and contributed to low level residual stress, minimal distortion, very small penetration depth and heat affected zone (HAZ) of
less than 100 µm. The micro hardness results indicated that the maximum value from laser welding in the HAZ was 370.2 HV
lower than the value from SMAW of 525.5 HV. The welded deposit rate for laser welding was with 26.5 mm³
/min remarkably
lower than the rate for SMAW of 1,800 mm³
/min.

Keywords

• laser welding
• shield metal arc welding
• heat input
• residual stress
• heat affected zone