Bending Cr-Mo-V steel plate 1

[bagnamento]

I am dealing with bending of a plate made of SA542D Cl.4 (21/4Cr-Mo-V), tempered at 1250°F (680°C), to make a cilyndrical shell.
The late is 51/2in. (138mm) thick and we cannot roll at a low temperatures such as 360-400°F (180-200°C) since the needed loads would be too high for our machinery.

Our customer suggests to bend at 900-1020°F (480-550°C) but as far as I'm concerned temper embrittlement is likely to occur in this temperature interval.

My suggestion would be to bend at approximately 1100°F (693°C) to avoid temper embrittlement.

Is that correct?
Can anyone give me tensile and yield strength data for this material in the 900-1100°F interval?

Thanks

 

[metengr]

The susceptibility to temper embrittlement between 885 deg F and 1050 deg F is based on alloy composition, but more importantly is a prolonged exposure effect. The time during PWHT or a low temperature stress relief is not of the duration to result in temper embrittlement for these alloys. You could evaluate the chemical composition and determine susceptibility to temper embrittlement using the information below;

http://www.btwcan.com/html/ppf8.html

As for your application, I would agree that you need to form using the higher temperature of 1100 deg F because the Cr-Mo-V materials tend to exhibit higher strength at elevated temperature as a result of vanadium carbides. Also, the 1100 deg F temperature is well below the original tempering temperature.

The yield strength for this material at 900 deg F is 47.8 Ksi based on information from Table Y-1 of ASME Section II, Part D. There are no reported values in this Table above 900 deg F because Section VIII limits this material at 900 deg F.

You might find the document below interesting information on 2.25%Cr-1% Mo-0.25V alloys;

http://www.pg.gda.pl/mech/kim/AMS/022003/ams022003004.pdf