[MW:18333] RE: 18323] preheat requirement for alloy steel

Purposes of preheat for alloy steel are:
(1) allow time for hydrogen to evolve from the weld
(2) promote a softer microstructure
(3) reduce residual stress
(4) help to control distortion

For stainless steels, hydrogen assisted cracking is typically not a
issue (there is no step change in solubility as occurs with alloy
steels). A greater concern is that a slower cooling rate increases the
probability of sensitization thereby increasing the risk of SCC and
other corrosion.

John A. Henning
Welding & Materials

-----Original Message-----
From: materials-welding@googlegroups.com
[mailto:materials-welding@googlegroups.com] On Behalf Of g.venkatesan06
Sent: Thursday, August 01, 2013 12:38 PM
To: materials-welding@googlegroups.com
Subject: [MW:18323] preheat requirement for alloy steel

Dear experts

why preheat is mandatory for alloy steel and not mandatory for stainless
steel. Give some metallurgical reason and code reference.

Is joining alloy with stainless steel what is the preheat requirement.

Regards
venkatguru

--
To post to this group, send email to materials-welding@googlegroups.com
To unsubscribe from this group, send email to
materials-welding+unsubscribe@googlegroups.com
For more options, visit this group's bolg at
http://materials-welding.blogspot.com/
http://www.linkedin.com/groups/MaterialsWelding-122787?home=&gid=122787&
trk=anet_ug_hm

The views expressed/exchnaged in this group are members personel views
and meant for educational purposes only, Users must take their own
decisions w.r.t. applicable code/standard/contract documents.
---
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-welding+unsubscribe@googlegroups.com.
For more options, visit https://groups.google.com/groups/opt_out.


______________________________________________________________________
The information in this email is confidential, and is intended solely for the addressee(s). If you are not the intended recipient of this email please let us know by reply and then delete it from your system; you should not copy this message or disclose its contents to anyone. The internet can not guarantee the integrity of this message. HAMON (and its subsidiaries) shall (will) not therefore be liable for the message if modified.
______________________________________________________________________

--
To post to this group, send email to materials-welding@googlegroups.com
To unsubscribe from this group, send email to materials-welding+unsubscribe@googlegroups.com
For more options, visit this group's bolg at http://materials-welding.blogspot.com/
http://www.linkedin.com/groups/MaterialsWelding-122787?home=&gid=122787&trk=anet_ug_hm

The views expressed/exchnaged in this group are members personel views and meant for educational purposes only, Users must take their own decisions w.r.t. applicable code/standard/contract documents.
---
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-welding+unsubscribe@googlegroups.com.
For more options, visit https://groups.google.com/groups/opt_out.