Need to improve Charpy Results
Need to improve Charpy Results
(OP)
Hello everyone,
We are working with 4130 for a part we are building and need to reach a Charpy impact result of at least 25 ft-lbs (avg.). We are falling way short (we are at 10, 4, 5...). From what I understand, results have been improved in the past by heat treating. Heat treating seems like it would hurt more than help in this case. What can I do to improve the results for the 4130?
Also, our tensile results are ~48,000 psi for yield, 87,000 psi ultimate; both seem low. But, our elongation at break is around 18% or so, which seems high...
I wish I had more data to give, but that is all I have at this point. Any suggestions?
Thanks
We are working with 4130 for a part we are building and need to reach a Charpy impact result of at least 25 ft-lbs (avg.). We are falling way short (we are at 10, 4, 5...). From what I understand, results have been improved in the past by heat treating. Heat treating seems like it would hurt more than help in this case. What can I do to improve the results for the 4130?
Also, our tensile results are ~48,000 psi for yield, 87,000 psi ultimate; both seem low. But, our elongation at break is around 18% or so, which seems high...
I wish I had more data to give, but that is all I have at this point. Any suggestions?
Thanks





RE: Need to improve Charpy Results
You need 25 ft-lbs at what minimum service temperature?
What is the original heat treatment of the 4130?
What are your minimum strength requirements for the part?
RE: Need to improve Charpy Results
If so then you should be able to improve properties by going through a controled hardening/tempering cycle.
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RE: Need to improve Charpy Results
You can improve ductility and toughness of this material by specifying a heat treatment condition. Your best bet would be a quench and temper heat treatment. The temper cycle should be outside of the 600-1070 deg F temperature range to avoid a reduction in ductility and toughness. However, you need to know your minimum strength requirements to assure selection of a proper heat treatment.
RE: Need to improve Charpy Results
Depending on the section size, a water quench and temper or a oil quench and temper treatment would greatly improve your impact strength. 25 Ft-Lb at room temperature is really not a problem with this material until you start getting hardnesses over 35 Rockwell 'C' or so and it sounds as if you don't need anywhere near this hardness.
The limitation with 4130 for quench and temper is the section thickness. Somewhere around 2 to 4 inches, you will not achieve through hardening, even with a water quench. Higher alloy content will be needed for the larger sections.
metengr, I believe you are describing temper embrittlement, a condition I had been led to believe did not apply to steels containing molybdenum (4130 has 0.15/0.25 Mo). Have I been misled? I have obtained very good impacts (>50 Ft-Lbs) with this material at tempering tempratures below 1000F. Am I doing something very unique? I'll admit that I was suprised at the impact levels I am achieving, but we do have a very consistent heat treating process.
rp
RE: Need to improve Charpy Results
RE: Need to improve Charpy Results
On a more theoretical note; I was always under the impression that quenching and other hardening processes generally caused the material to be more brittle. Am I wrong there, or is this some sort of special case?
Thanks
RE: Need to improve Charpy Results
From what I have read you need to be at or above 0.75% Mo to really delay the effects of embrittlement for this material. Of course, tramp elements will be equally as important in increasing susceptibility to TE.
RE: Need to improve Charpy Results
= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection
http://www.trent-tube.com/contact/Tech_Assist.cfm
RE: Need to improve Charpy Results
My number for 2" and 4" material, normalized, are in that range. The hardness is around 85 Rb with 27% El and 63% Ra. I only have Izod values, which are around 78.
The annealed material has an Izod of 45, hardness Rb 86, El 28%, Ra 56%, TS 81,000, and YS 53,000.
RE: Need to improve Charpy Results
RE: Need to improve Charpy Results