Hardening an L& R Frizzen

[M. De Land]

I should have added on to the last sentence that this is the explanation of how annealing hard steel occurs.Changing the martinsite back into pearlite by heating through decalesence and slowly cooling allowing the molecular change back to non hardening carbon.

 

[LRB]

Sorry, but pearlite is not carbon, but a compound of ferrite/iron and carbon/cementite. Martensite is not hardened carbon. It is the resulting product of a mix of iron and carbon that has been hardened by heat treating. There are no molecular changes in steel because steel is a crystalline structure and has NO molecules. Groups of atoms make crystals, groups of crystals make grains, groups of grains make steel, or iron. When heating steel, the pearlite structure begins forming austenite, which when completed is an homogenous solution of iron and carbon. This transformation begins at around 1333°f/1340°f. Ac 1. Ac 2 is when the steel becomes non-magnetic at exactly 1414°. Ac3 is when with increased heat above the non-magnetic state, the austenite has reached a completely homogenized solution, at which point the steel is rapidly cooled forming martensite, the hardened form of steel, then for most uses it is tempered. This is all a matter of a shifting of the carbon and iron atoms making up the atomic lattice structure, by the effects of heat. When you quench you are locking the atoms in position. Not molecules. When you temper you allow carbon atoms that are under heavy stress to basically relax a bit by a slight shift back towards where they started from before the heat treating began.

 

[M. De Land]

According to the 1924 edition of the Machinist hand book, ( source material) sections 3-7 Martinite is a "hardening" form of carbon not "hardened" carbon.
Pearlite is changed into Martinite after fully passing through decalescence.
Recalescence is reached at a lower temperature as the steel cools, than is Decalescence which is when Martinite is changed back to Pearlite and depending on overall carbon content can be any where from 85 to 215 degrees different.
Steel is made hard by quenching before the recalescence occurs after fully passing through decalescence.
I'll go with Machinest hand book on this one.

 

[LRB]

Well, to start with, it is Martensite. Not martinite. It is neither a hardening form of carbon, nor is it hardened carbon. It is the hardened condition of steel. You are right with recalescence and decalescense, but otherwise you don't really know what you're talking about, do you? Unless you are heat treating a simple carbon steel in the forge, R and D are really meaningless. They are simply a given if you know the necessary temps you want. A person may not even see them in some light conditions. If you are heat treating in a well regulated HT oven, you would never see either of them take place. :v

 

[M. De Land]

I know what I read in the source listed and that is what was conveyed to the forum.
You are quite correct about the spelling, my bad but then you knew perfectly well what I meant and that is the real purpose.
Perhaps you know more than the authors of Machinist Handbook, possible I guess. :wink:
The book is geared more for machinists use than a metallurgical technical writing.

 

[M. De Land]

Going back to spark color from a given frizzen: One would think that a sharp flint that sparks more than does a dull one would give off a different color of spark in that it should be cutting deeper and removing more steel but I have never noticed this if it is occurring.
In both of my flint locks the spark color appears unchanged wither there are lots of sparks from a freshly tuned or new flint or a dull one that does not spark as well.
So far I can't see that spark color has any meaningful advantage or disadvantage to ignition but rather the amount and focus of the spark shower certainly does.