Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Welding 304H PWHT and Hardness issue

Welding 304H PWHT and Hardness issue

Welding 304H PWHT and Hardness issue

Hello everyone,

I have a question regarding the welding of 304H plates. My client is asking a hardness of 200BHN max in the HAZ. Normally we have 225BHN in that zone. The welding process is SAW. The raw material has a BHN of 180. Is there a way to play with SAW variables or with PWHT variables to reach 200BHN?

RE: Welding 304H PWHT and Hardness issue

So the raw material is right at the max allowed hardness.
That is cause for concern. If it was 20pts lower then you would be in business.
The 200max does sound very tight.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

RE: Welding 304H PWHT and Hardness issue

I thought to use a high pre-heat temperature which may be reducing the hardness of the welded metal as an alternative per API Code. But, it may apply to CS material, but not 304H. Alloy 304H is sensitized after ending, which becomes an issue in the H2S service without PWHT.

RE: Welding 304H PWHT and Hardness issue


1) Your client is clueless about stainless steel, as is anyone worried about hardening in the 'heat-affected zone' in 300 SS.
2) I hope you are not trying to measure BHN of the 'HAZ' using BHN. (or really, anywhere - BHN should be banned from everywhere other than foundries).

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

RE: Welding 304H PWHT and Hardness issue


Well, actually we have been asked to find BHN in the HAZ. My client is a huge company with probably more than 100 engineers in its technical office. I am new to this field so I cant confront anyone, just trying to get more information. I read somewhere that PWHT of 304H is actually bad for material. But I dont have a literal reference to support my argument.

RE: Welding 304H PWHT and Hardness issue

1. Austenitic SS cannot be PWHT unless you use a full solution anneal. Any lower temp will promote the formation of Cr carbides and sensitize the material. This lowers its corrosion resistance significantly.
2. A std BHN indenter is way too large to be using on a HAZ of a weld. Select a more appropriate method.
3. The max hardness on Aus SS is rarely limited, unless you are preventing the use of cold worked material. In the specs for annealed material this 304N is limited to 98HRB (201BHN). Expecting a little senitization in the HAZ from welding you would have to allow some margin for this to increase. It sounds like they just copied the value for annealed material and didn't give this any thought.
The question that you can ask is why the weld hardness limit is set the same as the raw material limit.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close