Retained austenite and impact toughness

Warren, yes for high alloy steels. Check out the Elmax tempering chart on the PDF. AQ~63HRC, drops off and then goes back up to 60HRC in that 550C/1025F range (very crude numbers from crude graph).

Me2, I thought the same thing, thought it was backwards from what I previously understood....that a faster quench will result in less RA. At first, I thought maybe their quench oil was actually slower than their compressed air quench, but the RC hardness graph shows higher hardness with the oil quench....so I am a little baffled that their CA quench had less RA than their Oil quench. Very odd to me.
 
chumaman said:
Is it? ...You have too much to improve :thumbup:
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Surely I have to, every time when I do something I do on improvements too. This is quote from material specification: "Elmax offers a possibility to make long-life, low maintenance moulds for the best overall moulding economy." I am limited by My baby-talking English but I am asking You is it what I wrote before about industrial forms? And You have right, they later wrote: "Elmax can also be used in the food processing industry, where a combination of corrosion resistance and wear resistance is required for cutting applications." I think that mean blades for use in industry not in the kitchen. Am I right? I never tried antiscale foil at higher temp as 1100°C (2010F) but I am curious and I will try.

Nathan: Thank You!
 
Willie71 said:
Isn't there a secondary hardening at the high tempering temp?
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I use it on a couple of My latest blades from Elmax. From curve in material specification I think the peak point is about 520-530°C (968-986F). Proved by ruler on screen, hahaha. My personal feeling from tests is that they are bit tougher than I tempered it at lower temperature (about 200°C [400F]).
 
Jesenius said:
I use it on a couple of My latest blades from Elmax. From curve in material specification I think the peak point is about 520-530°C (968-986F). Proved by ruler on screen, hahaha. My personal feeling from tests is that they are bit tougher than I tempered it at lower temperature (about 200°C [400F]).
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I was thinking the lower temper would result in increased toughness as you are avoiding the secondary hardening.
 
The secondary hardening range is a range of embrittlement. Lower tempering is preferred, or higher, but right in the middle decreases corrosion resistance and toughness.
 
Willie71 said:
I was thinking the lower temper would result in increased toughness as you are avoiding the secondary hardening.
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My furnace needs long time to cool down for tempering at secondary temperature so My steps are following: after HT I take it to kitchen stove and temper at 180°C (356F) for 2 hours. That give Me time to cool down furnace to the 520°C (968F). After cool knife to room temperature I temper it twice to secondary hardness. I know it is weird mixture but it works for Me. :)
 
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