Punch Tool Steel Properties

[MechPhil]

I am designing a down hole punch tool.

It is required to punch through0.430" thick (OD 5.555) casing made of Super 13 Chrome 110ksi material. The punch button is 0.675" diameter.

So far the tungsten carbide buttons crack and teh last one disintergarted and wiped out the test fixture.

The compression load through the button to shear is 110,000 lbs and teh compression rating is of the order 240,000 psi.

I want to use a tool steel button heated and temprered, and to cover all basis I'm considering, D3, D6, S1, 440B and CPM M4. I struggling to determine which is the best to use of any of these grades as I only seem able to get basic data or rudimentary wear vs toughness characteristics. The button will only ever be used once and tehn replaced.

I've tried Crucible, Matweb, Globalspec for material data.

What I would like is material properties like tension, tensile yield or better still compression data for heat treated materials of D3, D6, S1 etc. Is these anything out there? I'm struggling to make a decision as to which material to go for. Can anyone point me to the data sheets I need?

Thanks

MechPhil

 

[TVP]

Welcome to the wonderful world of tool materials. Obtaining data on all of the different grades using the same type of testing can be difficult. Your best option is to contact a metallurgist at Carpenter or Crucible and personally discuss the requirements, including your need for test data. Based on the description, I would look at PM M4 (both Carpenter and Crucible offer a PM grade M4). It is really good when you need both hardness and toughness.

 

[tripleZ]

You're hitting around 150 tons per square inch (TSI)...that's aggressive. I've got a powder metal application where I'm hitting a spot load of 120 TSI with a gradient down to 55 TSI in other areas of the punch. For the toughness/wear resistance combo, I'm a fan of Uddeholm's Vanadis 4 or their K340. Both grades are similar, with the first being P/M in nature and the second being more akin to wrought. Vanadis 4 has worn a bit better for me, but the K340 has been better at resisting gross cracking at the point of the spot load. Heat treated they're at 56-58 HRC.

For the record, I've used CPM, Carpenter, ASP, Uddeholm, etc., for tooling. My best experience thus far, with regards to technical support and recommendations, has been with Uddeholm.

Are you using straight carbide tooling? Could you use a carbide tip brazed to a softer base that would offer you the wear you need while giving you the "spring" in a softer steel punch?

 

[Pressed]

Call a Crucibe Service Center and request one of their tool steel data books, mine is half-sheet size with an orange cover. But unless you have a specific tool failure one old rule on material for press tools is to start with a W1 or O1 and go from there. As you haven't a tool steel failure yet, you might try one of those and see.

Carbide has differing mixes that have similar trade-offs as steel does, ie: hard to soft/brittle to tough. Though for heavy impact shearing, carbide and PM has low limits and the material you are working with is tough. All material has limits but for impact shearing of heavy section, high alloy material, I have better experience with tradition tool steel.


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[kenre]

Look up the specs on S7 tool steel, shock resisting with high hardness.

http://www.retallickeng.com.au

Was told it couldnt be done, so
i went and did it!

 

[Helicopterjunky]

S7 tool steel is a great material but past experience has taught me that you have to double temper it at fairly high temperatures to get a combination of good toughness and wear resistance. Don't worry about giving up on surface hardness as your application needs a tough material foremost.