PENGARUH JUMLAH TEMPERING TERHADAP STRUKTUR MIKRO DAN SIFAT MEKANIK PADA MATERIAL BAJA HIPEREUTEKTOID

Akhmad Saufan, Sri Bhima Haryadi

Abstract


This research heated hypereutectoid steel to the austenisation temperature of 930 oC, followed by quenching and some tempering of 1, 2, 4, and 6 times at 100 ° C for 10 minutes on it and saw the impact of the treatment on changes of the microstructure, strength, ductility, and hardness. The testings were performed by metallographic, tensile  and Vickers hardness tests.

The test results showed that full annealed steel having lamellar pearlite structure and proeutectoid cementite along the grain boundaries of pearlite has the lowest hardness, 177 VHN, compared to the results of other heat treatments and domestic punch products. Meanwhile the quenched steel has the highest hardness, 857 VHN. The hardness number will continue to drop to 827, 825, 810, and 766 VHN for 1, 2, 4, and 6 times tempering, respectively. It is similar phenomenon for the tensile strength of 1.4, 1:03, 1.12, 0.99, and 0.81 kN/mm2. Conversely, the ductility will rise by increasing the number of tempering. It was indicated that the elongation increase from 0 to 0.4, 0.5, 0.6, and 0.8%. The quenched steel and all the tempered steels have similar microstructure consisting spherical and fine phase. Only quenched steel has plate phase morphology which changes after tempering process.

 

Kata kunci: punch, hypereutectoid steel, quench, temper


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