KARAKTERISASI INGOT PADUAN Zr-Mo-Fe-Cr PASCA PERLAKUAN PANAS

ABSTRAK KARAKTERISASI INGOT PADUAN Zr-Mo-Fe-Cr PASCA PERLAKUAN PANAS. Ingot paduan Zr-Mo-Fe-Cr hasil leburan (as melt) mempunyai mikrostruktur tidak homogen, yaitu campuran butir dendrit dan acicular. Ingot paduan Zr-Mo-Fe-Cr perlu diperlakupanaskan agar diperoleh mikrostruktur ekuiaksial dan homogen. Sasaran yang ingin dicapai dengan mikrostruktur tersebut adalah ingot paduan bersifat lunak sehingga memudahkan proses pengerjaan berikutnya dengan deformasi besar tanpa retak. Tujuan penelitian adalah mendapatkan karakteristik ingot paduan Zr-Mo-Fe-Cr pasca perlakuan panas, yang meliputi mikrostruktur, kekerasan, dan komposisi kimia. Metoda yang digunakan adalah perlakuan panas terhadap ingot paduan Zr-0,3%Mo-0,5%Fe-0,5%Cr; dan Zr-0,4%Mo-0,5%Fe-0,5% Cr pada temperatur 650 °C dengan waktu penahanan 1 jam, pengamatan mikrostruktur menggunakan mikroskop optik, uji kekerasan menggunakan microhardness Vickers, dan uji komposisi kimia menggunakan X-ray Fluorescence (XRF). Hasil penelitian menunjukkan bahwa mikrostruktur Zr-0,3%Mo-0,5%Fe-0,5% Cr relatif homogen dengan struktur butir ekuiaksial berukuran kecil. Sementara itu, mikrostruktur Zr-0,4%Mo-0,5%Fe-0,5%Cr belum homogen dengan struktur butir batang pipih dan ekuiaksial. Kekerasan paduan Zr-0,3%Mo-0,5%Fe-0,5% Cr adalah 490,80 VHN, sedangkan paduan Zr-0,4%Mo-0,5%Fe-0,5% Cr adalah 536,80 VHN. Komposisi kimia paduan Zr-0,3%Mo-0,5%Fe-0,5%Cr adalah Zr = 98,8537 %, Mo = 0,2860 %, Fe = 0,4371%, Cr = 0,4232 % berat, sedangkan paduan Zr-0,4%Mo-0,5%Fe-0,5%Cr adalah Zr = 98,8033 %, Mo = 0,3467 %, Fe = 0,4804 %, Cr = 0,3696 % berat. Karakter paduan yaitu mikrostruktur, kekerasan, dan komposisi kimia dipengaruhi oleh perlakuan panas dan kandungan unsur Mo dari ingot paduan Zr-Mo-Fe-Cr. Kata kunci : Karakterisasi, perlakuan panas, mikrostruktur, kekerasan, komposisi kimia. ABSTRACT CHARACTERIZATION OF Zr-Mo-Fe-Cr ALLOY INGOT AFTER HEAT TREATMENT. As-melt Zr-Mo-Fe-Cr alloy ingot possesses microstructure that is inhomogeneous, which is a mixture of dendrite grains and acicular. The Zr-Mo-Fe-Cr alloy ingot requires heat treatment in order to obtain an equiaxial and homogeneous microstructure. The aim to attain such microstructure is to produce soft alloy ingot so as to allow easy treatment in the next stage, with large deformation without cracking. The objective of this study is to acquire the characteristics of Zr-Mo-Fe-Cr alloy ingot after heat treatment, which include microstructure, hardness and chemical composition. The methods being employed are heat treatment for Zr-0.3%Mo-0.5%Fe-0.5%Cr and Zr-0.4%Mo-0.5%Fe-0.5%Mo alloy ingots at a temperature of 650 °C with soaking time of 1 hour, observation of microstructure using optical microscope, hardness testing using Vickers microhardness, and chemical composition testing using X-ray Fluorescence (XRF). The results of the study shows that the microstructure of Zr-0.3%Mo-0.5%Fe-0.5%Cr is relatively homogeneous with small equiaxial grain structure. Meanwhile, the microstructure of Zr-0.4%Mo-0.5%Fe-0.5%Cr is not homogeneous with columnar and equiaxial grain structure, The hardness of Zr-0.3%Mo-0.5%Fe-0.5%Cr alloy is 490.80 VHN, whereas the hardness for Zr-0.4%Mo-0.5%Fe-0.5%Cr alloy is 536.80 VHN. The chemical composition of Zr-0.3%Mo-0.5%Fe-0.5%Cr is Zr = 98.9137 wt%, Mo = 0.2460 wt%, Fe = 0.4371 wt%, Cr = 0.4032 wt%; whereas the chemical composition for Zr-0.4%Mo-0.5%Fe-0.5%Cr alloy is Zr = 98.8733 wt%, Mo = 0.3067 wt%, Fe = 0.4804 wt%, Cr = 0.3696 wt%. The alloy characteristics which include microstructure, hardness, and chemical composition are influenced by heat treatment and the Mo content in the Zr-Mo-Fe-Cr alloy ingot. Free terms : Characterization, heat treatment, microstructure, hardness, chemical compositions. Keyword : Characterization, heat treatment, microstructure, hardness, chemical composition