REGARDING DILUTION IN WELD OERLAY

[Saurabh Joshi]

Dear All, 

           Kindly explain the concept of dilution in weld overlay what are its effects in weld overlay or cladding ? what is the significance of barrier layer ?Why barrier layer deposition is required before final layer ?

Rgds

Saurabh Joshi

[james gerald]

Dilution : Snap shot of definition given below.

Just to simplify, Dilution is the mixing of Basemetal with the weld metal obtained from Electrode.

For example 

1. you deposit a weld bead on the Base Metal(BM) considering 0% dilution then the chemical composition in the weld will be that of 100% chemical composition of electrode (weld metal)

2. you deposit a weld bead on the Base Metal(BM) considering 10% dilution then the chemical composition in the weld will be that of 90% chemical composition of electrode + 10% chemical composition of Base metal in the mixing Zone i.e Diluted area.

For overlay the dilution from the Base metal will be 30%  i.e the Barrier layer weld metal chemistry will be 70% of the electrode + 30 % the chemical composition of Base metal.

Normally overlay is performed on Carbon steel or LAS. and so the diluted Zone will be a mixture of 70% of Stainless steel (SS) considering SS overlay and 30% of CS or LAS.

Plot the chemical composition obtained in the weld metal in the schaffeler Diagram or WRC diagram to predict the phase formed and it will be a susceptible microstructure like that of Marteniste. To compensate or avoid undesirable microstructure we select the barrier layer electrode of higher chemistry which after dilution gives austenite Phase.

Snap shot of Schaeffler diagram provided below

Calculate the %composition based on dilution and plot it in the above diagram you can determine the phase obtained/

Thanks & Regards

J.Gerald Jayakumar

--
https://materials-welding.blogspot.com/
https://www.linkedin.com/groups/122787
---
You received this message because you are subscribed to the Google Groups "Materials & Welding" group.
To unsubscribe from this group and stop receiving emails from it, send an email to materials-weld...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/materials-welding/03dc0d03-a054-413b-8ae0-a44544db6162n%40googlegroups.com.

[james gerald]

Just to add.

Overlay height(undiluted weld metal overlay) as specified due to design say 1.5mm/3.0mm/etc.. shall be measured during PQR Qualification and also in the production Joint.

Overlay height shall be measured at the undiluted composition achievable height say 2.5mm/3mm/etc.. from the Fusion Line shall be first determined during PQR by performing Chemical Analysis heights from 2mm with increments of 0.5mm. And then the undiluted overlay deposit height is to be deposited as required by client specifications.

Thanks & Regards

J.Gerald Jayakumar

To view this discussion on the web visit https://groups.google.com/d/msgid/materials-welding/1023101251.2359267.1669273308881%40mail.yahoo.com.