Grain Orientation Issue w/Normalized 4140. 3

[tc7]

I need to progress rapidly through a new weld procedure PQR and the only material we could get overnight was a section of AISI 4140 normalized 9-inch diameter x 12-inch long round bar. From this it was sliced into six each 6”x12” test plates. However this leaves the grain orientation parallel to the 12-inch length where it should be transverse to it (the bevel will be along the 12-inch side), which will mean that bend testing and tensile testing will place elongations across the grain rather than with the grain and this may affect test results.

The mill cert says the material was “cold str., Normalized at 900 deg C”. Does the normalizing reconfigure the grain structure of rolled bar material to where I should not need to be concerned with grain orientation affecting tensile and bend tests? Additionally, the plates will be heat treated to HRC 30-32 prior to welding.

Thanks for all advice

 

[TVP]

As long as the bar does not have an excessive amount of non-metallic inclusions, I would expect tensile and bend testing to be ok. What is the sulfur content and/or the inclusion rating according to ASTM E 45? Anything less than 0.015% S or an ASTM E 45 rating of 1.5 or 2 should be fine, especially since it will be normalized and then Q&T.

 

[metengr]

I would agree on being able to pass the bends and tensile tests with the subsequent heat treatment. However, you will still have directionality associated with the bar product.

 

[tc7]

Thank you both.

TVP-
I do not have inclusion information, is this a test normally done by the mill? Also, the sulfur is less than .01% - why do you mention sulfur as a possible concern on this question? Why or how could higher values of sulfur affect bend or tension tests?

 

[CoryPad]

Inclusion testing is done by the mill only if the customer asks for it.

Sulfur produces inclusions like MnS stringers. They reduce elongation, especially in the transverse direction.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[tc7]

Thanks Corypad - that is a good little tidbit of information that I have never come across.


I will be doing this procedure as a double bevel plate test, plates will be Q&T prior to weld. We will be using ER80S-Ni1 root and 1st pass with 120S-1 fill. Mechanical tests will be done in as-welded condition (no stress relief). Tension, bend and Charpy tests are required. With this in mind, are there any cautions or concerns that I need to worry about?
Thanks again to all.

 

[metengr]

tc7;
The only concern with Q&T is to watch your heat input. The rest looks ok to me.

 

[tc7]

Met-
I often search for heat input reference data or limits in terms of kJ/inch but this is rare information to find on 41xx steels and other mild steels. Reference values for the "T8/5" you once told me about is also non-existent for 41xx in the public domain. Any suggestions on that?

Lacking a kJ/inch or a T8/5 value to help me back into ideal amp and travel speed, I will use the following as a start:
400 deg F preheat;
500 max interpass;
180 amps on fill pass; probably less on root & first pass;
~24 volts;
weld speed ~8 in/min;
finish off with the ubiquitous "wrap & slow cool".

 

[metengr]

tc7;
The interpass temperature at 500 deg F is a good choice to avoid changing bulk properties.

 

[metengr]

tc7;
Take a look at the link below, it might be of interest to you. Also, credit for this link is from my newsletter subscription with

welding-advisers.com

http://www.thyssenkrupp.com/en/presse/art_detail.html&eid=tk_pnid1240

 

[tc7]

Thanks Met - I'll be talking with Thyssen SOON!!!

Say, if you look at my procedure outline above, I am using 80S-Ni1 for the root and 1st pass; will this impair or prevent any post production RT examination that will be required??

 

[metengr]

tc7;

Say, if you look at my procedure outline above, I am using 80S-Ni1 for the root and 1st pass; will this impair or prevent any post production RT examination that will be required??

No.