AISI 4145 or SAE 4145 confusion... 7

[acrmnsm]

I'm not sure if I'm posting this in the right place so please correct me.
Our company in the oil industry use various "4145" materials, some from bar and some from tubing to machine as end subs for test pieces and end subs/parts for some downhole tooling. We have been having issues with our materials specs where suppliers are often asking for comncessions as our spec is too tight and often confusing. I have been tasked with getting to the bottom of checking and revising the mats specs in this area.
In the first instance I am having difficulty finding a spec for 4145. Its seems that SAE now control and publish this under J404? Is this correct? What is the definitive source for 4145 spec?
The problem is that we get offered 4145 mod, which as far as mech props go often meet our needs, but this appears to be a proprietary spec rather than a standard as I can find no ref to it in SAE.
So I wonder if anyone has any knowledge/info they could share with me so I can try and steer this in the right direction.

 

[micalbrch]

Check here for AISI 4145 spec.:

http://www.steel-grades.com/Steel-grades/Carbon-steel/aisi-4145.html

Check here for SAE 4145 spec.:

http://www.steel-grades.com/Steel-grades/Carbon-steel/sae-4145.html

 

[mrfailure]

First of all, SAE and AISI 4145 are the same material (often referred to as AISI/SAE specs). All the designation refers to is the required chemical composition, nothing else. This material has been assigned a UNS number (UNS G41450), which you should use to determine conformance (UNS has replaced SAE/AISI). UNS alloys are published in a book you can get from ASTM, which also lists specifications which use that grade of alloy. I typically report the common designation and UNS on reports. If the most important requirement to you is mechanical properties and the modified composition does not fall within 4145 guidelines, then you should consider whether to allow it as an authorized substitution.

 

[dgallup]

I would be looking for an ASTM spec that covers this material. Chemistry only specs are normally not sufficient for any critical application.

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[CoryPad]

SAE J404 is a current standard and does include 4145, but it is composition only. ASTM A29 for bars also includes 4145 and specifies composition and size tolerances. You can use other ASTM standards for mechanical properties of bars. ASTM A519 is for seamless tubing and includes 4145.

 

[acrmnsm]

Yeah as I understand it the UNS number is not a complete spec only a chemistry thing. This from wikipedia says:

A UNS number alone does not constitute a full material specification because it establishes no requirements for material properties, heat treatment, form, or quality.

Secondly the links above from micalbrch are from a chinese steel supplier, whislt I thank you for googleing for me, I appreciate your help. I can google all kinds of internet refs to 4145 but I kinda want the definitve spec..

 

[acrmnsm]

Corypad thank you, I shall look at ASTM A29 and ASTM A519 cheers.

 

[metengr]

Look at ASTM A 322 for starters.

 

[redpicker]

In general, standard 4145H will only harden to meet the typical downhole tool requirements in sizes less than 6.25" diameter (and that is with a spray water quench). To meet the mechanical property requirements with larger sizes, the manufacturers will "modify" the chemical ranges, usually to increase the Manganese, Chromium, and/or Molybdenum contents. When they do this, the steel mills cannot certify the material as 4145, so they put 4145M, meaning a modified 4145. Since these alloying elements are more expensive than iron, this modification increases the cost, so some manufacturers and steel mills are reluctant to say exactly what limits they are using, but they will use enough to get the job done.

I have never seen much point in nitpicking the difference between 4145/4145H/4145M. Anyone who understands the reasons for this does not have a problem with the chemistry being slightly higher in Mn, Cr, and/or Mo. Those that don't understand the reasons, well, they don't understand so there isn't much to be gained by arguing with them. As has been said, it is much more important that the material possesses the required mechanical properties at the required depth below the surface. The chemical analysis just allows the processor to get there.

rp

 

[acrmnsm]

RP this is exactly my point, but the people in supply chain won't have it. They want a separate spec for each and I just want a mechanical requirements spec to get the material to do a job. I want a mats spec that is wide and includes all variants that meet the min yield and charpy requirements.

 

[redpicker]

This is easy.

C: 0.42-0.48
Mn: 0.65-1.20
Cr: 0.80-1.45
Mo: 0.15-0.50

Standard levels for the rest. Have a separate spec for 4140/42 tubes (mainly so they don't try to use 4140 bar).

Make it a requirement that each heat & each size have a mechanical test performed for each heat treating run. And be specific about the location (pitch diameter of the smallest thread).

Also make it a requirement that someone in your organization sign off on the test results (preferably, you). Also, put in your spec who to contact (again, preferably you) if there are any technical questions to the spec.

Your supply chain wants a spec they can give a supplier that will tell the supplier exactly what is needed so your buyer can give it to a bunch of different vendors and choose the one with the lowest price and/or best delivery. Your buyer does not want the vendor to call him back with any questions. Your buyer does not care if the material will be suitable for the job, only that he gets a good price for it.

rp

 

[acrmnsm]

redpicker, cheers, this is pretty much the spec I have written in terms of chemistry except the 4140/42 bit. I am plotting to put 3 clauses defining min yield, hardness and charpy for 110ksi, 120ksi and 125ksi, which are the mins we need for various designs. the buyer just picks a clasue depeing on what we tell them...

 

[mrfailure]

acrmnsm,

I would approach this a little differerntly. Since mechanical properties are what you really are trying to obtain, I would specify to commercial specifications that include required mmechanical properties, which are going to be the result of heat treatment and processing for individual alloys. For bar as an example, you should look into the classes within ASTM A434. These are classified by tensile properties, and you can call up a suppliemental requirement for your hardness requirements (though note that Charpy is not part of either the spec or listed as a callable supplemental requirement). Composition can be amongst alloy steel series listed (including 4100). I suspect you will have more success finding the right supplier by specifying in this manner.

 

[redpicker]

A suggestion. Make it clear that the 125K material is acceptable for the 110K (although your hardness ranges may not match exactly). Otherwise, expected to be asked this question, repeatedly.

rp

 

[acrmnsm]

Yeah, we are going to have the 110ksi with no max yield etc.