Heat Treat Calculator

By DaveBoyer (*****)

Date 07-03-2012 05:16

I doubt it, there is a little more to heat treatment than that.

By unclematt (***)

Date 07-03-2012 11:05

Good Morning;
Thanks for the reply. I was looking for something that would be just rough number; within a range. Say you had 4140 80 ksi yield 22 HRC. You ran it for two hours at 1150F. What hardness range could you expect. What temp would you need to run to get ???? HRC. Would 1150F change it at all? Something along those lines.

Have a good one;
Matt

By DaveBoyer (*****)

Date 07-04-2012 02:35

In the case You mentioned, 4140 @ 22RC, 1150 for 2 hours would not change it, as the 1150 is below the temper temperature for 22RC.

In this case You know that You are starting with a quenched and tempered material of a known hardness, somthing You did not mention in the original post.

By unclematt (***)

Date 07-04-2012 02:46

Hello;
I apologize for the omission. I was just looking for something very general. By reading your post, if I hope to change the condition of the material, I would have to go above the temper temperature. We are trying to qualify a welding procedure welding 4140 to 1018 and it didn't pass the 10 Vickers Hardness Survey for NACE compliance on the 4140 side. It passed MT and bends. Our resident metallurgist suggests 1250F for one hour. I will look at the certs when I get back to work Thursday to verify the temper temp. He states that this should get us to where we need to be. I do appreciate your replies.

Have a happy and safe 4th;
Matt

By DaveBoyer (*****)

Date 07-04-2012 03:35

The problem with welding a hardenable material is that an area in the HAZ will be heated above critical, but be cooled fast enough by the surrounding material to act as a quench. This area will have untempered martinsite, and be too hard and too brittle.

I would follow Your metalurgist's suggestion and heat to 1250 for 1 hour at temperature immediatly after welding, and see what You get. If it is still too hard, talk to Him again and see if He thinks a higher temperature will solve this problem without creating any other ones.

By G.S.Crisi (****)

Date 07-03-2012 19:14

I don't know of any, but things change so rapidly in the last times that I wouldn't be surprised if some company has introduced one.
Try on the Google.
Giovanni S. Crisi
Sao Paulo - Brazil

By unclematt (***)

Date 07-03-2012 21:30

Good Afternoon;
Thanks for the reply. I used to work in a heat treat shop but that was twenty something years ago and what little I knew has gone the way of the Dodo. I did search a little on Google. I will try some more.

Have a good Evening;
Matt

By 803056

Date 07-04-2012 17:02 Edited 07-04-2012 17:04

ASM publishes books on this subject. They have graphs that show the user what microstructures will result with different heat treatments.

The problem described here is that you do not know what you are starting with once the welding is completed. As our good friend Dave said, you could have untempered martensite in the HAZ assuming you didn't use sufficient preheat thereby allowing rapid cooling.

Assuming you used sufficient preheat and maintained sufficient interpass temperature, the HAZ should be free of martensite. However, even if proper PH and IPT is maintained some strain hardening could result due to the high residual stresses. That can be mitigated by thermal stress relief at the temperatures appropriate for the materials being joined accompanied by slow cooling.

You mentioned your metallurgist made a recommendation. I would like to believe he consulted his references on heat treatment before he made his recommendation. As Dave said, listen to him.

Best regards - Al

By unclematt (***)

Date 07-04-2012 20:26

Thanks to both you and Dave for the replies. We are going to weld two more coupons of the 4140 material and see if the increased heat will have the desired effect. In welding to the WPS, we started with a 400F preheat and a 550F interpass temp. These were adhered to during the test. We did, however, allow the coupon to cool before subjecting to PWHT in a furnace. It has been suggested that we will PWHT in place with a rosebud immediately after welding. I had done another of these a while back and the same thing occurred. I appreciate you all taking the time to give your advice. I enjoy working with the engineers and metallurgist in figuring this stuff out. As soon as we get something figured out, I will let you all know.

Have a good day;
Matt

By DaveBoyer (*****)

Date 07-05-2012 04:10

I was not clear in My post, nor did I know You were using pre heat and monitoring interpass temp.

If there has been fast enough cooling in the range from about 1500f down to about 800f to cause hardening, then the part should cool to about 150f before tempering so that all of the martinsite that is likely to form will have the chance to form, THEN You temper it.

If the preheat, interpass, post heat and slow cooling all work like they are supposed to, seperate additional tempering shouldn't be needed.

By unclematt (***)

Date 07-05-2012 10:45

Thank you sir. We will give it a shot.

Have a good one;
Matt