Thread: Thiers Issard grades

Originally Posted by Tony Miller

Joe,
Those numbers would be inline with hardening and annealing good steel and similar to what Mike has stated.

Tony

I just was wondering whether his "heat treating" is necessarily hardening.

Originally Posted by xman

So why do you think is it that they choose to use lead?

TI says:

"LEAD HARDENING IS THE ABSOLUTE BEST METHOD FOR THE HARDENING OF RAZORS AS THE STEEL IS HEATED ABRUPTLY (WHEN PLUNGED INTO THE BOILING LEAD) RIGHT TO THE CORRECT TEMPERATURE! THUS GUARANTEEING THE MOST PERFECT PROPER HEAT TREATMENT."

The lead bath is a very good method of heat treatment, meaning hardening of the steel. They have to quench the blade in something after heating it to "set" the martensite formation at the edge at least. It'd be nice to know what they use for quenching medium. Oil would be good and likely a standard quenchant for most good razor steels. Water is very quick and would risk a large number of cracks/blade failures at those very thin dimensions. But they could also use a bath that was capable of about 400 F and go right into quenching and tempering at the same time.

The comment about annealing at 300 C is strange to me. That's about 572 F and would likely draw the hardness of the steel down to a lower Rockwell number. It'd make the blades easier to hone for sure. I'd like more info about that particular aspect.