HUBUNGAN KOROSI BATAS BUTIR BAJA TAHAN KARAT TIPE 304 METODE ASTM A262 DAN TEMPERATUR SENSITASI
Intisari
Korosi batas butir terjadi pada material AISI 304 tersensitasi. Proses sensitasi terjadi akibat pembentukan senyawa kedua (Cr23C6). Dampak sensitasi pada AISI 304 dengan dan tanpa proses solution treatment (ST) berbeda. Pengujian kualitatif ASTM A 262 telah dilakukan untuk melihat keberadaan dan jejak senyawa karbida dengan variasi temperatur 600,700, dan 8000C. Pengujian kekerasan Vickers dilakukan untuk melihat perubahan sifat mekanik setelah perlakuan panas. Bentuk karbida di temperatur sensitasi 600oC berbentuk ”dual” (non ST) sedangkan ”step” (ST). Suhu 700 dan 800oC dengan kondisi ST dan non ST telah membentuk ”ditch” penuh. Nilai kekerasan terendah ada di kedua kondisi pada suhu sensitasi 7000C. Keberadaan α ‘martensit memberikan kerentanan terbentuk sensitasi pada material 304 tanpa kondisi ST di suhu sensitasi 600oC.
Kata Kunci :
Korosi batas butir, Baja Tahan Karat 304, Sensitasi, Karbida, perlakuan panas
Abstract
Grain boundary corrosion is undergone at sensitized AISI 304. Sensitizing process is undergone that caused the formation of second coumpound (Cr23C6). The effect of sensitization at AISI 304 with and without solution treatment (ST) is quite different. The qualitative test of ASTM A-262 was conducted to observe chrom carbide and its path on grain boundary with the variation of sensitizing temperature for 600,700, and 800oC. The Vickers hardness test was done to observe the change of mechanical properties after heat treatment. The shapes of carbide at sensitizing temperature of 6000C are classified as “dual” (non ST) and “step”. The temperature of 700 and 800oC with the various conditions of ST and non ST formed full “ditch” structure. The lowest value of hardness on both conditions is at sensitizing temperature of 700oC. The existence of α ‘martensite structure quite contributes the susceptibility of forming sensitizing condition at 304 materials without ST process at sensitrizing temperature of 600oC.
Keyword :
Grain boundary Corrosion, Stainless Steel 304, Sensitization, Carbide, Heat Treatment