Lower transformation temp for C.S. 2

[vesselguy]

Hello,

Anyone know where I can find the lower and upper transformation temperature for the typical P1 to P5 materials we use?

I'm checking a WPS in one of the essential variable is the PWHT temp for C.S. is stated as 660°C. The equipment is a combo of P1 and P4 material and they get PWHT together. The 660°C is fine for the P4 material PWHT temp; but I want to check if 660° is in the transformation range for the C.S. If so, then that is not good.

Thanks.

 

[metengr]

Yes. A good reference for lower critical transformation temperatures is ASME B31.1, see Table 129.3.2. If you don't have a copy of B31.1 handy, I will list several of the published LCT;

carbon steel (P-No1) 1340 deg F
carbon-moly (P-No3) 1350 deg F
1-1/4 Cr - 1/2 Mo (P-No 4) 1430 deg F
2-1/4 Cr - 1 Mo (P-No 5A) 1480 deg F

 

[metengr]

Also,you only need concern yourself with exceeding the lower critical transformation temperature during a subcritical PWHT because of the potential to form austenite in the base metal heat affected zone. During subsequent cooling, the austenite could transform to untempered martensite (undesirable).

 

[JoeTank]

metengr,
Could you recommend a website or reference that provides good background on transformation temps? I'm thinking of something very basic that us non-metallurgy guys could grasp. Most of my world is made of P1 materials. I'd like to be more informed on the topic.
Thanks

Steve Braune
Tank Industry Consultants

http://www.tankindustry.com

 

[metengr]

SteveBraune;

Here are several decent web sites regarding steel and heat treatments

http://www.key-to-steel.com/Articles.htm

http://www.steeluniversity.org/content/html/eng/default.asp?catid=3&pageid=650269858

http://serkanakinci.tripod.com/id19.html

Actually, if you Google "heat treatment of steel" you will receive plenty of hits on the public domain. What I have done over the last several years is look specifically for lecture notes on this subject. There are a number of PowerPoint presentations by materials professors at various universities. I have compiled a rather extensive list of files on heat treatment of steel.

 

[weldtek]

metengr,
Thanks for the excelent references!

 

[vesselguy]

metengr,

Thank you for your tips. I followed your guide and found the table in B31.1. I never thought to look in B31.1 (I don't work with that code) since I don't recall seeing it in B31.3. Thanks.

Yes, my concern is if the temp is higher than the LTT then I get transformation to austenite. Hence, the WPS submitted to me as is is acceptable.

Thanks again.