THE EFFECT OF COOLING MEDIA VARIATIONS IN THE SMAW WELDING PWHT PROCESS FOR SS400 STEEL MATERIALS ON THE VALUE OF HARDNESS AND TENSIL STRENGTH
Baja Mild Steel merupakan bahan utama pembuatan Arm Engine sepeda motor. Dalam proses produksi Arm Engine diperlukan proses pengelasan. Pada proses pengelasan Arm engine, menyebabkan tegangan sisa dan perubahan sifat mekanik pada material. Untuk memperbaiki perubahan sifat mekanik akibat proses pengelasan maka dapat dilakukan proses PWHT (Post Welding Heat Treatment) yang bertujuan untuk mencari pengaruh media pendinginan pada proses PWHT (Post Welding Heat Treatment) terhadap nilai kekerasan dan kekuatan tarik pada material Baja SS400.
Penelitian ini menggunakan metode eksperimen dengan memvariasikan media pendingin dalam proses PWHT setelah proses pengelasan SMAW pada material baja SS400, selanjutnya masing-masing variabel diuji kekerasan dan uji tarik. Spesimen yang sudah diuji kekerasan dan uji tarik kemudian dianalisa pengaruh dari varibel bebas terhadap variabel terikat. Variabel bebas meliputi media pendingin pasir pantai, pasir sungai, pasir gunung.
Berdasarkan hasil penelitian dapat disimpulkan bahwa variasi media pendinginan berpengaruh pada nilai kekerasan dan kekuatan tarik. Dimana proses PWHT dengan suhu 900°C dengan holding time 10 menit menyebabkan nilai kekerasan dan kekuatan tarik mengalami penurunan. media pendingin pasir sungai memiliki nilai kekerasan terendah yaitu sebesar 98.3 HRB untuk daerah weld metal, 97.1 HRB pada daerah HAZ, 95.4 pada daerah base metal. Sedangkan untuk nilai kekuatan tarik paling besar dalam proses PWHT yaitu variasi media pendingin pasir pantai dengan nilai 413.93 Mpa dan regangan 33%
Kata kunci : Baja SS400, PWHT, Uji Kekerasan, Uji Tarik, Arm Engine.
Mild Steel is the main material for making Arm Engine motorcycles. In the Arm Engine production process, a welding process will required. In the Arm engine welding process causes residual stresses and changes in the mechanical properties of the material. To improve changes in mechanical properties due to the welding process, a PWHT (Post Welding Heat Treatment) process can be carried out which aims to find the effect of cooling media in the PWHT (Post Welding Heat Treatment) process on the hardness and tensile strength values of SS400 Steel material.
This study used an experimental method by varying the cooling media in the PWHT process after the SMAW welding process for SS400 steel material, then each variable was tested for hardness and tensile test. The specimens that have been tested for hardness and tensile testing will analyzed for the effect of the independent variables on the dependent variable. The independent variables include the cooling media for beach sand, river sand, and mountain sand.
Based on the research results, it can be concluded that the variation of cooling media affect the hardness and tensile strength values. Where the PWHT process with a temperature of 900°C with a holding time of 10 minutes causes the hardness and tensile strength values to decrease. River sand cooling media has the lowest hardness value of 98.3 HRB for the weld metal area, 97.1 HRB for the HAZ area, 95.4 for the base metal area. Whereas for the highest tensile strength value in the PWHT process, namely the variation of beach sand cooling media with a value of 413.93 Mpa and 33% strain.
Keywords : Steel SS400, PWHT, Hardness Test, Tensile Test, Arm Engine.