Crack Propagation 1

[unclesyd]

Not very practical now, but very interesting research.

http://www.mpg.de/english/illustrat...Releases/2003/pressRelease20031113/index.html

 

[tedg]

Hi unclesyd:

Thanks for the suggestion. The interesting findings described in that paper are an extension of the well-known relationship between brittleness and crack propagation.

We did some simple work on this some time ago to demonstrate that ductile fracture travels a few feet per second, while brittle fracture is measured in thousands of feet per second.

When choosing tool steels, we pay careful attention to
fracture toughness that is an indication to the resistance of the material to the onset and growth of cracks. It is
different from impact toughness which is given in most
specs and reported as IZOD or Charpy V-notch.

 

[TVP]

Ted,

Thanks for the information. I find it very interesting that you are using fracture toughness as a selection criterion for tool steels-- the first time I have ever heard anyone doing so. Care to share any data? As you already know, Charpy or Izod data is all that is readily available from suppliers...

 

[tedg]

unclesyd

You are right; most specs give only Charpy and/or Izod, but an increasing number of manufacturers will provide fracture toughness data as K1C values if you ask for it.

Clearly, however, fracture toughness is only ONE of the properties that must be considered in mold steel selection

I'd be happy to share data. A copy of the paper I wrote on this topic can be downloaded at <

http://www.nidi.org>.

Go to the technical data section and search for technical paper 10070 &quot;understanding and preventing cracks in mold steels&quot;.

If you have any difficulty with the website, and if you so wish, you can forward your e-mail address to me at ftg@gerson.ca and I'll send you a PDF copy of the paper.

All I would ask in return is that you let me have your views on the paper and the suggestions contained in it.