Chromoly equivalent 3

[guimba]

Hello, I am looking to duplicate a mountaineer's piton made out of forged chromoly steel - I'm assuming 4130 - with a machinable alternative that is of like strength and low cost. Any ideas? Thanks!

 

[metengr]

guimba;
Do you know all of the design specifics related to this item? What is the strength level you need? Reverse engineering without all the necessary design information can be a problem.

 

[CoryPad]

4130 is both machinable and low cost.

 

[guimba]

I forgot to mention that the material wants to have a RHC of at least 28, from a piton standard I uncovered. This is needed so it can wedge in concrete or other hard materials. It will be used as part of a hook & line kit to exert a pulling force; no loss of life or danger if it fails. I have no strength requirement other than to duplicate the 4130. Is it castable? Would the casting be heat-treatable as would the machined part? Thanks for the help.

 

[lgearhart]

There's a reason it's forged 4130 or something similar. That is a reasonably strong steel, good ductility, readily available in wire, bar, or forgings. It certainly can be cast, and heat treated castings will be strong, but they will also be brittle. If you plan on this part seeing impact loading, say from a hammer pounding it into a rock crevice, then casting will not be optimum.

 

[guimba]

What would be the correct material callout for the cast part? Make from AISI 4130 PH alloy steel? Would another alloy in the series be indicated? Thanks.

 

[guimba]

Also, one of our suppliers offered to cast the part in ASTM A27 Grade 65-35 carbon steel. Is this a suitable material? Should I specify that it be heat-treated to RHC 28-32? Thanks!

 

[ornerynorsk]

Please don't use castings on mountaineering hardware! Forgings that are properly annealed, trimmed, machined, stress relieved, heat-treated, and then x-rayed, are the proper way to go. There are applicable standards to follow when producing hardware that will be used to support a human load, and for life-critical components.

 

[redpicker]

Why would you x-ray a forging?

rp

 

[ornerynorsk]

If you were the guy hanging from a piton on a rock wall, wouldn't you feel better if the company that made it went to some effort to keep rejects out of the product stream? Granted, were not talking about huge cross sections and the problems you see with those, but there is a human life depending on that little piece of steel. It takes, what, a minute to x-ray a piton or carabiner sized piece?????

 

[redpicker]

Obviously it would be in my best interest not to trust my life on defective equipment. I'm just questioning the ability of the x-ray inspection to identify a defect in a forged piton.

rp