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[MW:2708] Re: SS Material purging

By Materials & Welding
In general there is no reason other than to remove moisture to preheat
Austenitic stainless steel as it is not sensitive to hydrogen cracking.
However, Martensitic and Ferritic stainless steels must be preheated
200-300C and 200 to 400C respectfully, for they are very sensitive to
hydrogen cracking.

Precautions with welding stainless steel is - cleaning , avoid using tools
(files, brushes grinders etc) that we previously used on carbon steels.

The Chloride and other halides can cause Stress Corrosion Cracking.

Best Regards,

Richard Beldyk PhD, PE
AWS CWEng
ASNT NDT Level III

Original Message:
-----------------
From: puneet takiar puneet1takiar@yahoo.com
Date: Sat, 18 Jul 2009 15:39:37 +0530 (IST)
To: materials-welding@googlegroups.com, puneet1takiar@yahoo.com
Subject: [MW:2703] SS Material purging


Dear Friends,
There are two queries :-

Why it needs pre-heating in welding of SS material. What is to be tsken
care in welding SS amterial.

Secondly, It is recommendable in DPT of ss materials, Penetrent should not
have or acceptable levels of chlorides and florides. Why? What should be
there percentage.

Regards,
puneet


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