4140 Hex Bar Availability/Substitute 4

[winchengr]

Have been using a 5/16" hex 4140 steel bar for 2 yrs and now can't locate. The bar is used as an input shaft and must be heat treated to Rc 20-26 and straightened within .020 in a 15" length.

Does anyone know where I can find this material?

An alternate of 12L14, heat treated to same hardness has been proposed. Would this be an equivalent substitute? Do not have any experience with HT 12L14. Would it be more or less likely to warp?

 

[strokersix]

You may be able to purchase small quantities of alloy hex from McMaster-Carr or other retail type sources.

I'm not sure 12L14 will respond to heat treat in the same manner as 4140. You should check this out.

 

[metman]

12L14 is a carburizing grade but might actually respond to heat treat to achieve 20-26 HRC. I could not find data here at home or at ASM site. Such low carbon content makes it borderline to respond to quench and temper.

AISI 1144 is typically supplied in hex and can be Q & T at 1000F to HRC 30 so maybe 1200F tempering temperature would give you 20-26. Straightness should not be any more problem than 4140 since 1144 can be oil quenched. One problem is that the supplier I am looking at does not stock it in 5/16 hex. 1144 is a free machining grade but not as mchinable as 12L14.

AISI 1045 is supplied in hex but again no listing for 5/16. But maybe another vendor would stock it. It can be water quenched and tempered at 1000F for HRC 22. Water quenching will induce more distortion but since you are straghtening anyway this should not present a big problem.

 

[TVP]

12L14 does not have sufficient hardenability and therefore will not respond to quench & temper treatments. metman's suggestion of an 11xx series grade is worth pursuing. 1137 and 1144 are both oil hardening grades, although I do not have any data in front of me to show if they can be fully hardened in 5/16 bar (holiday from work). Also, you want to check out Niagara LaSalle's Stressproof product, which is essentially 1144 that is heavily drawn to increase mechanical properties, etc. No need for Q&T and the subsequent distortion for hardness in the range of 20-26 HRC. Use the following link for more information:

http://www.niag.com/us/products/stressproof/index.shtml

 

[Compositepro]

Central Steel and Wire (800-521-8510)lists 41L40 5/16" hex in their calatog.