The Effect of Holding Time Variations on Hardening Process Against Hardness JIS 9 SUP Steel

Seringkali pisau yang diproduksi oleh pandai besi mengalami retak dan rompal bahkan patah pada bagian mata pisaunya, sehingga petani karet harus sering menggantinya dengan pisau yang baru. Penyebab pisau sadap buatan pandai besi ini mudah rusak karena metode perlakuan panasnya dilakukan secara tidak tepat. Untuk meningkatkan kekerasan logam perlu dilakukan proses heat treatment salah satunya adalah proses hardening. Setelah dilakukan proses hardening maka dilakukan proses quenching guna menghasilkan kekerasan yang tinggi. Selain itu, meningkatnya nilai kekerasan dipengaruhi oleh waktu penahanan. Berdasarkan permasalahan diatas maka dilakukan penelitian dengan tujuan meningkatkan kualitas kekerasan bahan pembuatan pisau sadap karet, yaitu material baja JIS 9 SUP menggunakan metode hardening dan variasi waktu penahanan. Penelitian ini merupakan penelitian eksperimen. Dalam penelitian ini menggunakan metode hardening, material baja JIS 9 SUP dipanaskan dengan temperatur 850°C, holding time selama 15, 30, dan 45 menit, serta menggunakan media pendingin oli SAE 20W-50. Sesudah proses hardening, dilakukan pengujian kekerasan Rockwell. Teknik analisis data yang digunakan yaitu teknik analisis deskriptif kuantitatif. Hasil dari penelitian ini menunjukkan bahwa spesimen baja JIS 9 SUP tanpa perlakuan mempunyai rata-rata nilai kekerasan 44,22 HRC, pada spesimen baja JIS 9 SUP yang sudah dilakukan proses hardening dengan variasi holding time 15 menit mempunyai rata-rata nilai kekerasan 62,17 HRC, pada spesimen baja JIS 9 SUP yang sudah dilakukan proses hardening dengan variasi holding time 30 menit mempunyai rata-rata nilai kekerasan 63,73 HRC, dan pada spesimen baja JIS 9 SUP yang sudah dilakukan proses hardening dengan variasi holding time 45 menit mempunyai rata-rata nilai kekerasan 60,98 HRC.

Often the knives produced by blacksmiths are cracked and broken even on the blades, so rubber farmers often have to replace them with new knives. The cause of this tapping blade made by blacksmiths is easily damaged because the heat treatment method is carried out inappropriately. To increase the hardness of the metal, it is necessary to carry out a heat treatment process, one of which is the hardening process. After the hardening process is carried out, a quenching process is carried out to produce high hardness. In addition, the increasing value of violence is affected by the time of detention. Based on the above problems, research was carried out with the aim of improving the hardness quality of rubber tapping blade materials, namely JIS 9 SUP steel material using hardening methods and variations in detention time. This research is an experimental research. In this study, using the hardening method, the JIS 9 SUP steel material was heated to a temperature of 850°C, holding time for 15, 30, and 45 minutes, and using SAE 20W-50 oil cooling medium. After the hardening process, Rockwell hardness testing is carried out. The data analysis technique used is a quantitative descriptive analysis technique. The results of this study show that JIS 9 SUP steel specimens without treatment have an average hardness value of 44.22 HRC, in JIS 9 SUP steel specimens that have been hardened with a variation in holding time of 15 minutes have an average hardness value of 62.17 HRC, in JIS 9 SUP steel specimens that have been hardened with variations in holding time 30 minutes has an average hardness value of 63.73 HRC,  and in JIS 9 SUP steel specimens that have been hardened with a  variation in holding time of 45 minutes have an average hardness value of 60.98 HRC.