سیستم های گرمایشی با PLC و کنترل فرکانس

An experimental study was performed to investigate the effect of tempering temperature and tempering time on hardness and fatigue resistance of 0.4% carbon steel. It was found that increasing tempering temperature above 550 °C or tempering time decreases the hardness of the material. It was also found that there is a maximum number of cycles to which the specimen can survive what ever the applied load was.