Analysis of the effect of Chromium concentration (Cr) in welding electrodes on Carbon diffusion (C) at weld interface of ASTM A213 T22 material using metallographic and hardness testing methods

C. Ruskandi, M.O. Firmansyah, W. Purwadi
2019 Dinamika Teknik Mesin  
A crack occurred in joinning superheater pipes made of ASTM A213T22 and ASTM A213T91 metals by welding. This crack located at the interface between parent metal and weld seam.There was the difference in Cr concentration between metal and electrodes which can caused carbon diffusion. According to Nemoto's research, this carbon diffusion could occur because the Cr concentration in ASTM A213T22 metal is lower than Cr concentration in the electrode. The diffusion of carbon can reduce the mechanical
more » ... properties of the parent metal and causing the formation of type IV weld crack. This study aims to analyze the effect of Cr concentration in electrodes on the carbon diffusion on the ASTM A213T22 parent metal interface. The metals are welded using the AWS A5.5 standard electrodes B9, B6, B3 and B1 with the difference in Cr content and then followed by post weld heattreatment at a temperature of 750 o C for 5 hours. Metallographic and hardness test results showed that the electrode B9 and B6 which have a greater Cr content than the parent metal caused carbon diffusion and the precipitation of carbide after heattreatment. Whereas electrodes B3 and B1 which have a lower Cr concentration than the parent metal did not cause carbon diffusion. The result proved that the diffusion of carbon on the weld of ASTM A213T22 metal occured on an uphill basis, namely carbon diffuses from a lower Cr concentration to a higher Cr concentration metals due to changes in carbon chemical potential gradients.
doi:10.29303/dtm.v9i2.301 fatcat:upei73lmlrhydgo62xpngq7yyi