625 Weld Overlay on SA516 Gr70 plate in 3G position

[Mohmmed Dudhiyawala]

Hi Everyone,

We have encountered as PQR for Inconel-625 WOL on SA516 Grade 70 Normalized plate in 3G position.

Two Anomalies were observed: 

1. After PWHT of 120 mins, Hardness in base metal dropped from average 164 HV to average 108 HV! Has anyone observed such a drop in hardness? Is it possible? 

2. 625 WOL is done using SMAW electrode from Special Metals, the Nickel content as per consumable TC is 65%. While in WOL chemistry, 1.5mm from Top, Nickel % came around 68%. 3% Higher!! Is this possible, in any case?

Thanks in advance from your expert views.

Regards,
Mohammed Dudhiyawala, IWE

[Mohd Siraj]

dear mohd,

1. what was base metal thickness? is PWHT done to qualified for two PWHT cycle?, 

      # hardness achieved  after pwht100-140 hv is normal.

2. if Nickle 68% is concern, try with GTAW process.

[Mohmmed Dudhiyawala]

Base metal thickness is 5mm & deposited WOL is also 5mm.

Hardness achieved is after PWHT 1 Cycle of 60 mins.