PENGARUH VARIASI SUHU TEMPERING TERHADAP KETANGGUHAN DAN STRUKTUR MIKRO BAJA S45C PADA APLIKASI POROS MOTOR RODA TIGA

            Motor roda tiga adalah transportasi yang digunakan untuk mempermudah pekerjaan mengangkut barang, bahkan sering kali memuat beban yang melebihi kapasitas angkutnya sehingga menyebabkan kerusakan pada poros roda. Poros yang terkena beban kejut biasanya disebabkan oleh kekuatan mekanik baja yang rendah, untuk meningkatkan sifat mekanik baja maka diperlukan perlakuan panas dan variasi suhu. Tujuan penelitian ini adalah mengetahui pengaruh variasi suhu pada proses heat treatment tempering terhadap ketangguhan dan struktur mikro baja S45C.

            Metode penelitian ini menggunakan jenis penelitian eksperimen dengan menggunakan material baja S45C. Material dilakukan perlakuan panas hardening quenching pada suhu 850 ºC dengan waktu tahan 60 menit dan didinginkan dengan air biasa, dilanjutkan dengan proses tempering pada media pendingin oli 20W dengan variasi suhu 550 ºC, 600 ºC, dan 650 ºC. Pengujian material dilakukan dengan pengujian impact charpy dan struktur mikro.

A three-wheeled motorbike is a form of transportation that is used to make the job of transporting goods easier, and often carries a load that exceeds its carrying capacity, causing damage to the wheel axle. Shafts that are exposed to shock loads are usually caused by low mechanical strength of steel. To improve the mechanical properties of steel, heat treatment and temperature variations are needed. The aim of this research is to determine the effect of temperature variations in the heat treatment tempering process on the toughness and microstructure of S45C steel.

This research method uses experimental research using S45C steel material. The material was subjected to hardening quenching heat treatment at a temperature of 850 ºC with a holding time of 60 minutes and cooled with plain water, followed by a tempering process on 20W oil cooling media with temperature variations of 550 ºC, 600 ºC and 650 ºC. Material testing was carried out by charpy impact and microstructure testing.

The results in this study obtained the highest toughness value at a temperature of 650 ºC with an average value of 1.84 J/mm2 and a ferrite phase percentage in the microstructure test of 68%. Meanwhile, the lowest steel toughness value was at a temperature of 550 ºC with an average value of 1.175 J/mm2 and a ferrite phase percentage in the microstructure test of 50%. From toughness and microstructure testing, it is known that temperature variations in the tempering process can have an influence on the toughness value of S45C steel, the higher the temperature during tempering, the higher the toughness value. Then, the results of the microstructure test show that after tempering with varying temperatures the S45C steel has formed a ferrite phase which is predominantly the result of martensite which has diffused during the heating process.

Key words: heat treatment tempering, S45C steel, temperature, three-wheeled motorbike