3" 4140 OQT

Date 01-09-2009 16:35

I was wondering if any body could help with info on this mat. We are welding a 3" dia 20" long 4140OQT mat. to a 3/4" 1018 CD mat. I have a preheat from Eng.calling for 600-650 deg. preheat using a ER70s-6 wire. My question involves the cooling of this after weld. Where can I find the cool down rate for this. We have a insulated cooling box that we put these in but it makes a big difference on how many pins are in the box at one time. Any help would be appreciated. Thank you.

By 803056

Date 01-12-2009 02:51

Take a look at the response list in the attached URL: www.aws.org/cgi-bin/mwf/topic_show.pl?tid=19352.

It is similar to your question. The temperatures can be converted by going to: www.onlineconversion.com/temperature.htm.

Basic suggestions:

1) Make sure the shaft is in the annealed condition.
2) Preheat to 650F. Use soaking heat.
3) Maintain preheat during entire welding operation.
4) Use E9018 or ER90S-X as the filler metal. Softer electrode material (E80 ksi or E70 ksi) is fine if it produces sufficient strength for your service conditions.
5) Stress relief after welding.
6) Retard the cooling rate by placing a large chunk of scrap that has been heated to 700F in with the welded pins to act as a heat mass. Slow cooling from 650F will help to minimize distortion between thinner (faster cooling) sections and heavier (slower cooling) sections and it will slow the cooling through the Ms-Mf temperature range.

I hope it helps you.

Best regards - Al

By drifter57 (**)

Date 01-12-2009 11:23 Edited 01-12-2009 11:59

Al,thanks for the response.I cannot get anywhere using the address listed.(probably because of my lack of computer skills).Is there another way to get to the attachement listed? Thnaks. EDIT_____ Sorry screwed up typing. Found it. Still my question is, is there an area in the code book that adresses cool down rate for a preheated part. I can find info for post weld heat treat but nothing on cool rate for this mat. Thank you.

By 803056

Date 01-13-2009 03:39

This is beyond the scope of materials found in AWS D1.1.

I looked at my ASM book, by it only listed isothermal curves. They are helpful, but they don't provide all the information we welders would like to have at our finger tips.

Basically, once the part is slow cooled below the Mf temperature, the cooling rate can be fairly rapid provided there isn't a danger of differential cooling rates between thick and thin portions of the weldment that can result in distortion damage.

Best regards - Al