Charpy Impact Toughness for Q&T 4140

[WmTu]

I'm looking for Charpy toughness of Q&T 4140 steel tempered at various temps, specifically Charpy at -40F. Strengths need to meet minimum 120/150ksi yield/tensile, 12/25 El/RA. Can anyone give me direction of where to look, this mechanical engineer has limited metals books. Thanks in advance for anyone's assistance in this matter.

 

[Cockroach]

Usually around 20 J or so, but at -45C. Close to what you are looking for, -40C is about -40F, so twenty joules.

Regards,
Cockroach

 

[WmTu]

Thanks Cockroach, but this engineer needs some good literature to that fact. We would be rolling 100 tons into product, I'd like to see test data including chemistrys, I understand we might have to control Sulfur and Phosphurous lower in order to obtain our desired Charpy. Any web sights or handbooks that would have this depth of info??

 

[dhengr]

WmTu:
“This engineer” should probably get some “metals books,” given that question.

That’s probably a pretty tough question for any of us to address off the top of our heads, any better than Cockroach did. These tests, and the results and reports are usually done for each heat of steel and/or for each batch of finished product. You can ask that they be done as part of the certification process and paperwork. When you’re talking about 100 tons of that type of material, which I assume you don’t just have laying in the back room, I would think you would want to talk with the likely suppliers. They will tell you what they can achieve and any special chemistry requirements, etc. to achieve what you need. You will find some very general info. on the subject in one of ASM’s Metals Handbooks. I don’t know that they have a tabulation of ranges of values, at different temps. for all of the various steels.

 

[Cockroach]

In the USA, Charpy is performed at room temperature. Typically you get 61 to 65 foot pounds. For NACE and cold engineering work, the specification is at -40C (-40F), the push is to quantify brittleness in relation to crack propagation from sites of imperfections. Pipelines and valves usually specify -45C, I have seen odd requests for -50C being pushed by non technical people who fail to have a grasp on the specifications. You can check the NACE spec, MR0175 in addition to CSA Z245.15.

In terms of chemistry, reduction in sulfur is usually because of concerns of sulfide stringers which provide a natural cleavage for cracking. There are several API papers on this given at conferences, surfing the net may give you information. But you would be better off consulting metallurgical references for the steel making industry.

Hope this helps, good luck.

Regards,
Cockroach

 

[WmTu]

Thanks Dhengr and Cockroach, both inputs have merits. Regarding books, if someone has a suggestion of a real good metals book, I'd gladly buy it. My best metals book I bought early in my career illustrates 4340 impacts at different temperings and cold temps, but not 4140. By its omission, I'm concerned the industry does not see 4140 being a good low temp impact steel? It would appear a little nickel in the steel is needed (as 4340 has) to provide more toughness at low temps. Regarding our foundary, they are somewhat limited in what alloying they can do, or producing low sulfur/phosphurous levels. As an example, they have mentioned the possible need for aluminum, but they can not do this. And my book doesn't even show an aluminum content in either of these alloys?? Thier meturgical experience is very limited in what it will take to get the strengths, ductilitys and impact we're looking for, that has led me to throw a note out here to see what bounces back. I need a good metallurgist consultant experienced in cold temp impacts, and haven't found one yet. I suspect there are a number of chemical mixtures that will meet this mark, we just haven't found one that comes with a guarantee. Appreciate all the comments, I've learned a lot in the digging I've done so far!!

WmTu

 

[Cockroach]

The ASTM website would be a possible good start. They do have software which lists many of the features you ask. Kind of expensive, but of value none-the-less. I use the Metals Blackbook, two volumes, one for ferrous and the second for non ferrous material. I also have a few metallurgical textbooks from the local university which are excellent resources. Perhaps going through the book store at your local campus and getting a few text from courses taught there would improve on your understanding of subject matter.

Regards,
Cockroach