https://www.youtube.com/watch?v=lOJHrkh__SQ
See if my explanations in that video make sense to anyone other than me.
Basically, too much carbon is possible, just as too little is possible. The region around 1450 has cementite and austenite mixed together. The cementite is the stuff we want in hypereutectoid steel. It adds wear resistance, and helps control grain growth. You want to dissolve enough cementite to put 0.6 to 0.8 % C in the austenite. Above that, and hardness gains are slim to none, RA goes up, and there is a greater risk of cracking both in the quench and in use.
See if my explanations in that video make sense to anyone other than me.
Basically, too much carbon is possible, just as too little is possible. The region around 1450 has cementite and austenite mixed together. The cementite is the stuff we want in hypereutectoid steel. It adds wear resistance, and helps control grain growth. You want to dissolve enough cementite to put 0.6 to 0.8 % C in the austenite. Above that, and hardness gains are slim to none, RA goes up, and there is a greater risk of cracking both in the quench and in use.
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