AISI 4340 vs AISI 4145H 3

[eltooon]

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.

 

[BMKR]

The difference is they are two different compositions of steel, 4340 is in two varieties AMS 6415 & 6414 (AQ and VAR).

http://www.matweb.com/search/DataSheet.aspx?MatGUID=2790f8e5ef46470995b7bfc2b59774f6&ckck=1

matweb isnt the best but its something to go off of

 

[stanweld]

The strength will be based on strengthening heat treatments - quench and tempering. You as the engineer can select a tensile strength and ductility level or they will be further defined in a Standard specification. The depth of hardenability is greater in the 4340 alloy steel.

 

[salmon2]

4340 has nominal 2% Ni, and 4145 doesn't.

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.

 

[TVP]

eltooon,

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

 

[salmon2]

TVP, That is an interesting alloy. Any idea about its availability? Thanks.

 

[redpicker]

salmon2, that material is a mainstay in the oilfield. Contact Timken for availability, as they (as well as other firms that supply material to the oil and gas industry) stock heat treated material that meet and/or exceed those properties. You do have to be specific as to your mechanical property requirements (pay attention to the location the test specimens were removed from), but it is readily available.


rp

 

[eltooon]

stanweld,

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?

 

[eltooon]

TVP, yes indeed it's used for oil & gas.

Is 4145H Mod equivalent to 4145H?

 

[salmon2]

Thank you, redpicker. A star from me for you.

 

[redpicker]

The "Mod" behind the 4145 notation only signifies the chemical composition has been modified from the standard AISI ranges. Usually, they will increase the Ms, Cr, and Mo contents and, perhaps, limit the P & S contents. The actual modifications are often dependent on size (increasing content with increasing size), so any specific limits you find on chemistry may not apply (for example, if the range is 1.00-1.25 for Cr, you may find a heat with 1.27).

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

 

[salmon2]

eltoon, sorry hacked your thread.

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.