Heat treating at various temps (metallurgy Theory)

[foxthor]

I have a question regarding the temperature used when quenching to achieve certain hardness. I have search on the Net and unable to find information about this.

If you quench steel bellow non-magnetic temperature, would you achieve a level of hardness above the non heat treated steel. For example if the starting HRC of the steel is 30, then you bring the steel (80crv2) to 700 C and then quench, would the hardness increase to say (45) HRC instead of the usual HRC of around 60 when done properly at 850 C. Can you choose what hardness to achieve through pre-quench temperatures? or does this need to be done through tempering.

The reason i ask i because i am making swords from 80crv2 but because these swords will be blunt training weapons that will be struck against other blunt swords often, the desired end HRC is 47-50.

Due to the limitation i have for tempering a large piece of steel (700-900mm) to 400+ C in order to achieve the desired HRC of 47-50. I thought maybe a sub optimal hardness for a sharpened weapon may be achievable via low temp quenching. I realise i may have this concept completely wrong and wondering if hardness can only be achieved at above non-magnetic temps.

 

[Storm W]

Have you read the knife steel nerds articles yet? That's the best place to start.

 

[Larrin]

You have to form austenite (nonmagnetic) to get martensite when you quench.
https://knifesteelnerds.com/2019/07/01/what-a-good-heat-treatment-can-and-cannot-do/
https://knifesteelnerds.com/2018/02/28/austenitizing-part-1-what-it-is/
https://knifesteelnerds.com/2018/04/10/what-makes-quenched-steel-so-hard/

 

[Willie71]

I have a question regarding the temperature used when quenching to achieve certain hardness. I have search on the Net and unable to find information about this.

If you quench steel bellow non-magnetic temperature, would you achieve a level of hardness above the non heat treated steel. For example if the starting HRC of the steel is 30, then you bring the steel (80crv2) to 700 C and then quench, would the hardness increase to say (45) HRC instead of the usual HRC of around 60 when done properly at 850 C. Can you choose what hardness to achieve through pre-quench temperatures? or does this need to be done through tempering.

The reason i ask i because i am making swords from 80crv2 but because these swords will be blunt training weapons that will be struck against other blunt swords often, the desired end HRC is 47-50.

Due to the limitation i have for tempering a large piece of steel (700-900mm) to 400+ C in order to achieve the desired HRC of 47-50. I thought maybe a sub optimal hardness for a sharpened weapon may be achievable via low temp quenching. I realise i may have this concept completely wrong and wondering if hardness can only be achieved at above non-magnetic temps.

Getting full hardness, and tempering back is your best bet. If you inadequately harden the steel, you get mixed structures, and performance will be sub optimal. Your better option, if you could call it that, is to use a lower carbon steel to limit how hard you can get the steel. You still need to temper to reduce brittleness though.

 

[milkbaby]

In addition to using lower carbon content steel, maybe you could carefully torch draw/temper your swords? Assuming double edged and most of the mass in the center, after you carefully clean up the surface, you could torch draw along the center and watch the color as it advances to the edge. Maybe worth practicing on some practice knives/swords first tho

 

[Stacy E. Apelt - Bladesmith]

Harden and torch draw. Been done that way for a thousand years ( using charcoal before torches).
I have seen old timers use a big block of hot steel on a handle ( looks like a damascus billet or quench tank heater) to run along the center of the sword and draw the temper.