I read on the webpage below that 440C is the hardest stainless available and will get to Rockwell C60. Is the manufacture process difficult compared to 304? I think it might end up more expensive. And where could I get some 0.2mm in R&D quantities in Europe? Thanks. Ant.

http://www.westyorkssteel.com/440C.html

antknee, referring to this and your other threads, would you consider revealing what you are trying to accomplish?

It could greatly help to focus the discussion.

Regards,

Mike

I need the hardest available stainless with a thickness of 0.2mm and a company who will supply it. It is for a R&D project and a critical component. The hardness just matters more than anything else, I've had some 304 SS with 800 N/mm2 hardness, some 316 with 1200 N/mm2 and some 302 with 1600 N/mm2 and it still wasnt hard enough.

This post is me asking is Rockwell C60 and 2000 N/mm2 in 440C stainless the end of the line? Who could supply some and will it be painfully expensive?

I don't work with stainless - I'm trying to find out what I need before moving on to the next of many problems. R&D is essentially wasting money on the wrong parts until after a few orders I finally get what I need...  :)

Well, that tells nobody nothing. I should think that from the replies in the other threads you would be getting the idea that greater hardness is not going to solve your "non-deformable, will not bend" problem, although again, nobody knows what that means in physical terms.

Glad I don't pay your R&D bills...

Regards,

Mike

Have you tried looking at razor blades.  A quick google returned sites that sold blades 0.25mm thick, would this do?  If the blade itself is too small, maybe you could contact the manufacturer either some of their stock or perhaps they could produce blades in the size you need.

I think you are approaching this from the wrong direction.  Get material that has the hardness and thickness you want and then find out what corrosion problems you have and modify the material to address those problems.

rp

440C is martensitic so it is hardenable via heat treatment unlike the austenitic 304 & 316 which are only work hardenable.  Yes, it can be heat treated to 60 HRC.  It is readily available and not particularly expensive or hard to work with.  There are specialty stainless steels which can reach slightly higher hardness.  ZDP-189 can be hardened to 67 HRC, that's the highest I know of.  It is less readily available.  

However, you still seem to be ignorant of the physical properties you desire.  Re-read some of the responses to your earlier posts.  All steels have virtually the same modulus of elasticity and will therefor deflect the same amount in a given geometry and loading.  The difference is the amount of deflection before the material yields.

 

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Thanks. I wasn't aware of ZDP-189, I will see if I can get hold of some of that rather than the 440C. I am aware of the modulus of elasticity, in my system 0.2mm stainless vibrates at almost exactly 100KHz. Any change of thickness or material and the frequency alters. I am researching an ultrasonic buzzer type part, the PZT vibrates at 100KHz and cannot be changed, so stainless and 0.2mm thickness cannot be changed. I need both at 100KHz to achieve maximum resonance of the system. I need the hardest stainless I can get hold of because a) it is acting like a spring, softer stainless won't spring back with the same force as the very hard stuff and b) there are other reasons I would have difficulty explaining.

Regards,

Ant.  

Sandvik is a European producer of strip steel that commonly stocks small thickness (0.1-1.0 mm) in stainless steels that can be heat treated to high hardness.  Take a look through their website on Knife steels and Spring Steels:

http://www.smt.sandvik.com/en/products/strip-steel-and-strip-based-products/

 

I haven't had any luck tracking down any ZDP-19 however I have come across the precipitation hardening stainless 17-4PH. If cold rolled to 1800N/mm2 it can then be heat treated to 2500N/mm2. That would be around 65-70 HRC

Sandvik didn't reply to my email so I will call them next week, there is also a company called Knight Strip metals who might stock some, I will try them. I will have to buy a laboratory oven or perhaps a pottery kiln. What would be the cheapest option?

Does anyone know the heating time for 17-4PH? The sandvik website said 1 hour at 575 Degrees C and another said 4 hours at 475 Degrees C. What would be the logic behind 1 hour or 4 hours?

Thanks,

Ant.

Look at a 17-4PH data sheet.
You age it to get it hard. Lower aging temps give higher hardness.
If you are going to grind or lapp this to your thickness I would harden it first.  Temp control isn't that big of a deal, +/-25F (+/-10C) is fine.  You may not hit peak hardness, but you will be close.
http://www.alleghenytechnologies.com/ludlum/Documents/17-4Cdate052510.pdf
 

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Plymouth Tube

That is a very good spot. I will ask for a datasheet when I order, 490-500 Degrees C for an hour will be pretty much there. It appears the aging process gives about 40% extra strength so getting 1800N/mm2 in a cold rolled 17-4PH will be more important than the exact temperature it is aged at (as long as I'm above the minimum temp). Thanks. Ant.

 

I've tried to source 17-4 PH cold rolled to 1800N/mm2 but had no luck. The U.K. stockists seem not to stock PH at 0.2mm at all and want to order from a mill, minimum quanity 5Kg for £1200+, and send me annealed which I'd have to subsequently have cold rolled.

As I only need 1Kg this seems a waste. I'm a bit stuck.

My thought is try US stockists next, find someone who will supply 1Kg annealed, ship it to the UK and find someone who will cold roll it.

Any advice/thoughts?

Regards,

Ant.

PH 15-7 Mo is common for snap rings and springs?

I've ordered some 17-7PH, the datasheet says it's almost identical to the 15-7Mo. It is in the annealed condition and 0.4 and 0.5mm thick, so now I need someone to cold roll it down to 0.2mm thick. Could you recommend someone to do that? It is just 2 sheets so a small order. Thanks. Ant.