High strength core with hard surface

[mhickl]

Hello, This is my first post to the site,I have googled many problems and this site seems to pop up quite a bit. I figured I'd give it a shot. I am designing an internal pipe gripping device. I have a center mandrel with several ramps on it. My slip/die will have corresponding ramps and the external surface will have teeth to grip the ID of the pipe. Pretty simple. In my simulations i am showing i will need a yield of 150ksi so i wont crush the slips. I'd like to have a case hardness of at least 60 HRC and min depth of .015 to .020. This part will be machined out of 9" round bar then using and EDM split into 6 sections. The question i have is what material will be good for this? (I also need some toughness, If the slip would beak, it would then be stuck in the pipe) I've had several suggestions but none seem to fit all the requirements. The Nitralloy 135 seemed to have to low of a yield, H13 seems like a good candidate, but is difficult to machine ( Turning the OD and maching teeth) aslso fairly expensive. Any other suggestions?

 

[Dougt115]

have you considered a coating like Chrome? Or would you expect that it will that chip in your application?

 

[hendersdc]

You haven't mentioned much about your application but these guys might make an off the shelf mandrel solution that would work for you: Schlumpf

 

[hydtools]

Look at AISI 4330 V-mod

Ted

 

[desertfox]

Hi

See this site for steels

http://www.oakleysteel.co.uk/high-strength-steel-plate

I would use a medium carbon steel and harden the outer surface to suit my requirements, steel grades S890Q and the grade below will exceed your strength requirement.

 

[mhickl]

Correct me if i am wrong, but doesn't the 4330V-mod have a surface hardness of 50-55 HRC after nitriding? A little low for the application. The mandrel we already have a material and prototype manufactured. I have not considered having it hardened but it may be a good idea for wear. I think we will try the H13. Thanks for the help and suggestions.