Yuanming,

As a general guide, a smith can use the modern methods such as a thermocouple with a readout. With this means he can calibrate his eye. Of course, for the eye to get accurate readings, the ambient light has to be consistent. With practice, one can get close. Getting close is sufficient when using middle of the road steels such as 5160. Very basic, uncomplicated. This has been done in historic settings for many decades.

If the smith chooses to use steels with higher alloy content or in combinations that make them particular to the heat treat, it may be necessary to use the modern digital readouts and other tools available today.

The temperature threshold of austenite formation is the baseline of historic as well as modern techniques. Using a magnet to find that threshold will get you close.

Every shop has different lighting and equipment. So you will have to determine the variables by practice and experimentation along with testing.

thank you for your advises and tips. I tried different tests, but haven't got an idea about how to find the threshold before. Your suggestions really open a window for me. really appreciated.

I teach several methods in my classes other than method all ready mentioned. the best I have found is to use table salt. Salt melts at 1474degf for 1075-1095 that is a good temperature to quench from and much more accurate than a magnet. I will run a gas forge down low sprinkle salt on the blade and slowly bring it up to temp watching for the salt to melt.

|quoted:

I teach several methods in my classes other than method all ready mentioned. the best I have found is to use table salt. Salt melts at 1474degf for 1075-1095 that is a good temperature to quench from and much more accurate than a magnet. I will run a gas forge down low sprinkle salt on the blade and slowly bring it up to temp watching for the salt to melt.

I love stuff like this.

|quoted:

I teach several methods in my classes other than method all ready mentioned. the best I have found is to use table salt. Salt melts at 1474degf for 1075-1095 that is a good temperature to quench from and much more accurate than a magnet. I will run a gas forge down low sprinkle salt on the blade and slowly bring it up to temp watching for the salt to melt.

salt melting observation. what a genius idea. it is really practical. I am definately gonna give it a shot. thank you so much. <img src=' http://www.americanbladesmith.com/ipboard/public/style_emoticons//biggrin.gi f' class='bbc_emoticon' alt=':D' />

|quoted:

I teach several methods in my classes other than method all ready mentioned. the best I have found is to use table salt. Salt melts at 1474deg for 1075-1095 that is a good temperature to quench from and much more accurate than a magnet. I will run a gas forge down low sprinkle salt on the blade and slowly bring it up to temp watching for the salt to melt.

Thanks Matt!

I think my head just exploded.

On a side note- when using salt to determine the correct temperature for quenching, how much pepper do you add? <img src=' http://www.americanbladesmith.com/ipboard/public/style_emoticons//wink.gi f' class='bbc_emoticon' alt=';)' />

-Evan

|quoted:

Thanks Matt!

I think my head just exploded.

On a side note- when using salt to determine the correct temperature for quenching, how much pepper do you add? <img src=' http://www.americanbladesmith.com/ipboard/public/style_emoticons//wink.gi f' class='bbc_emoticon' alt=';)' />

-Evan

I've watched Matt make salsa and teach class, I know he puts pepper on everything!