PENGARUH SINTERING DENGAN QUENCHING MEDIA PENDINGIN AIR, AIR GARAM DAN OLI SAE 30 TERHADAP KEKERASAN DAN STRUKTUR MIKRO PADA PADUAN BESI-KARBON BjTP24

Abstract

This research studied the effect of sintering by quenching variation of the cooling  medium that water, salt water, and oil where the oil is used oil SAE 30. In this study, the material that used is the Iron-Carbon BjTP24. are used 4 samples of iron of a kind, one sample is observed the microstructure and properties of hardness, and the remaining of which three samples get heat treatment that sintering up to 725⁰C and then, in-quenching by different cooling medium, that is water, salt water (10 grams of salt and 10 ml water ), and oil SAE 30. Then the four samples are tested Vickers hardness properties and microstructure. The decrease of the hardness properties of the sample occurred on the cooling medium oil SAE 30 are 16.15 HV or 9.2%. The increase of the hardness properties of the sample occurred on the cooling media water and salt water are 29.65 HV, or 16.6% for the media water cooler and HV 76.15, or 43.4% for the cooling medium salt water. The cooling rate of the salt water is faster than the water and oil due to the salt water, when the water has evaporated, going veil of water vapor, but there are specks of Na⁺ion and Cl^-ion on the entire surface of the workpiece, the veil of water vapor be divorced by spots Na⁺ion and Cl^-ion. Such cases was ongoing and the resulting cooling was not blocked, so that the workpiece would cool quickly and the result would be high hardness properties. The decrease hardness properties of the samples occurred on SAE 30 oil is caused by a slow cooling process. There was also a grain coarsening which the constituent atoms that have not had time to fix its position that directly inflicts the grains become more rude