The objective continued in this work is to improve the characteristics mechanical properties of high- strength A3S steel produced at the Panda Central Workshops of Gecamines. The steel grade studied contains quantities important manganese in proportions ranging from 2 to 4.6%. Various treatments thermal has summer realized in view to improve machinability while designing properties mechanics that meet the requirements of their use.Samples in the raw casting state have presented a hardness of 407.8 HB and a resilience of 4.3 J/cm 2. Annealing at 773°C followed by holding for 4 hours and slow cooling in the furnace to a speed of 20°C per hour helps to reduce hardness up to 200HB with increased resilience up to 28.3 J/cm 2. A quench was then carried out and made it possible to retain a heating temperature of 900°C and water as a cooling medium; which allowed to increase hardness and resilience until values respective of 343 HB and 19.7 J/cm 2. The final result obtained after tempering leads to a hardness of 217 HB and a resilience of 19.7 J/ cm2.It emerges from the tests realized that it is possible to modify and improve the hardness and resilience of the studied grade using thermal cycles appropriate.
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