AISI 4340 vs AISI 4145H
AISI 4340 vs AISI 4145H
(OP)
Can anyone please advise the difference between AISI 4340 and AISI 4145H?
I cannot find mechanical properties (yield strength, tensile strength and so on) of AISI 4145H.
Many thanks.
I cannot find mechanical properties (yield strength, tensile strength and so on) of AISI 4145H.
Many thanks.





RE: AISI 4340 vs AISI 4145H
matweb isnt the best but its something to go off of
RE: AISI 4340 vs AISI 4145H
RE: AISI 4340 vs AISI 4145H
You can use 4140 as a close reference for 4145H and I think you can find 4140 anywhere. 4145H will have slightly higher strength and lower ductility for final properties if both go through same heat treatment. Of course autenitizing temperature of 4145H is lower than 4140. Why 4145H in the first place? It is very similar to 4140 but its availability is probably 10 times less than 4140 and harder to weld.
RE: AISI 4340 vs AISI 4145H
Is this for an application in the oil & gas industry? Here is a datasheet for Astralloy 415H Mod that is used in the quenched & tempered condition with a UTS of > 140 ksi. 4340 is usually quenched & tempered to a UTS of 160-220 ksi.
http://www.astralloy.com/pdf/4145h.pdf
RE: AISI 4340 vs AISI 4145H
RE: AISI 4340 vs AISI 4145H
rp
RE: AISI 4340 vs AISI 4145H
do you mean the UTS is to be specified by the buyer? So the alloy, for instance 4145H, from manufacturer A could be different from that from manufacturer B?
I'm wondering if any industrial/international Standard has specific requirement on UTS and other mechanical properties?
RE: AISI 4340 vs AISI 4145H
Is 4145H Mod equivalent to 4145H?
RE: AISI 4340 vs AISI 4145H
RE: AISI 4340 vs AISI 4145H
eltooon,
Yes, for these materials, it is not uncommon for the user to specify not only the mechanical properties, but also the test location. These materials are typicallhy sold as round bar, in various sizes up to 10 inch or larger. And, yes, different manufacturers have different requirements for Tensile, Yield, CVN testing, and hardness, as well as different requirements on test location (1 inch below the OD, Mid radius, etc...), so the firms that stock the material will have the material qualified to meet a variety of requirements. API Specification 7-1 is the most common industry standard used for drill collar material, but most manufacturers have additional requirements in addition those specified by API 7-1.
Welding this material is difficult. Very specific pre-heat and post heat cycles must be used as cracking in the heat affected zone is likely the weld procedures are not followed. And, while many consider this to be an oil-quenching grade, most of this material is heat treated with a water quench; with uniform quenching, cracking is usually confined to the ends of the bars, which get cropped after heat treatment. As a result, NDE after heat treatment is usually considered mandatory, typically with UT.
rp
RE: AISI 4340 vs AISI 4145H
This 4145H Mod is abosultely not equivalent to 4145H. One of significant alloy addition is Ni up to 1%, which is usually none in standard 41XX. So it is good for large diameter stuff also in compliance with NACE 0175, for which 41XX does not have enough hardenability.