school project, some help requested

[duncanmclawd]

Hi,

I'm studying for industrial engineer and i gotta do a schoolproject now for the course "Materials-choise"...
We have to select the best possible material for a object, with help of the Ashby-materials-database. As object i picked a blade of a fillet-knife

I now need to find requirements for that filletknife-blade...
Here are the ones I was able to find already:

- has to be sharp and stay sharp as long as possible
- has to be hardenable to at least 52 Rc and ideally to 55 or even 57 Rc
- minimal toolingcosts for the manufacturer
- the blade has to be bendable for at least 10 to 15°
- very good corrosion resistance
- a low percentage of chromium because i have been told it is somewhat toxic...

This is good already but i still need some more demands for the blade... anyone can help a little???

Also, i wonder what the exact manfacturing-proces would be for a fillet knife? I mean a descent, pricey one
Stock removal ? hardening? sharpening?

All advice welcome...

Take care

 

[Redguy]

Chromium in a knifeblade is NOT toxic. Don't believe me, believe the standards of international food industry, where using stainless steel is obligatory. I'm sure you know stainless steels contain more than 14% chromium. You can't have good corrosion resistence without chromium. Period.

Anyway I think the best steel for your project is 12C27 (sandvik steel) or AEBL, but 420 HC, 440 A, B & C should work fine too. They are way harder than 55 HRC if done right, bendable much more than 15°, kinda inexpensive and easy to machine.

 

[Redguy]

Okay, there are some compounds where chromium can be toxic, but this positively not true for metallic alloys.

 

[Pete1977]

When I worked on party boats, we filleted hundreds of fish a day, from small 6 inch redfish, to 40 lb codfish, to 5 foot long wolffish, and used nothing but a Dexter Russell high carbon 6 to 8 inch boning knives. they were stiffer than a conventional filet knife, stayed sharper longer, and were extremely easy to sharpen as well as inexpensive, in case one went overboard, was stolen, or broken.

Pete

 

[s0rce]

Heh, I'm taking an Ashby-Materials Selection course now too, Stainless Steel is definately the best material but there are others that might come out well in the selection process but in actual use won't be practical like Silicon, Boron or Diamond.

 

[Halfneck]

Look at Spyderco's H-1 Steel knives. Rust-Proof.

 

[Jeff Clark]

I assume that you want to mass produce these knives so you need a material that is machine blankable (can be die cut). For this you can't have too much carbon or hard alloying elements (vanadium, molybdenum, or tungsten for example). The most common alloy used for filet knives is Sandvik 12C27 (which is a simple and clean stainless with moderate carbon content). Buck knives use 420HC (High Carbon), not 420-J2, so that it can be machine blanked. H1 is a newer type of stainless that has nitrogen in it to provide exceptional rust resistance. You might be able to use 440A, but the other 440-series alloys would be hard to stamp out.

Since you are working with a thin blade for a filet knife I would expect to start from flat rolled stock. You would stamp the outline and maybe any rivet holes and grind the blade bevel. All this works easily if you use 12C27 or 420HC. If you use harder alloys you may need the blades laser or water jet cut and need tough drill bits for any holes. 12C27 and 420HC can easily be hardened into the range of 56-58 RC.