Hasil fabrikasi pipa-pipa baja karbon rendah dalam satu standar produk dari beberapa produsen hanya disesuaikan terhadap persyaratan sifat mekanis seperti tegangan luluh, kekuatan tarik dan komposisi kimia sesuai grade standar produk. Kriteria seperti ini memungkinkan variasi yang berbeda terhadap komposisi kimia dan struktur mikro, dimana variasi itu mampu mempengaruhi ketahanan korosi bahan. Penelitian ini menggunakan dua sampel material pipa yang berasal dari produsen berbeda. Untuk itu, dilakukan pengujian laju korosi, komposisi kimia, metalografi dan karakterisasi produk korosi. Hasil pengujian menunjukan bahwa laju korosi kedua sampel tersebut berbeda. Perbedaan ini disebabkan adanya perbedaan struktur mikro dimana kadar perlit pada kedua sampel berbeda. Sampel A dengan kadar perlit yang lebih tinggi memiliki ketahanan korosi yang lebih rendah daripada sampel B karena adanya efek galvanik mikro antara ferit dan sementit pada mikrokonstituen perlit. Hasil penelitian membuktikan bahwa semakin tinggi kadar perlit maka semakin rendah ketahanan korosinya. Selain itu, terdapat perbedaan pada kadar komposisi kimia tingkat unsur paduan kecil seperti sulfur, mangan, kromium, dan tembaga yang boleh ditambahkan pada baja. Namun demikian, perbedaan kadar paduan tersebut tidak begitu menentukan karena kadar paduan yang ditambahkan sangat rendah.
Results fabrication of low carbon steel pipes that include in one standard product from several manufacturers only adapted to the requirements of the mechanical properties such as yield stress, tensile strength and chemical composition according to the grade of product standard. That criteria allows the variation of chemical composition and microstructure, where the variation that can influence the corrosion resistance of the material. This study used two samples of pipe materials originating from different manufacturers. For that, the rate of corrosion testing, chemical composition, metallography and characterization of corrosion products are tested. The test results showed that the corrosion rate of the two samples are different. This difference is attributed to differences in the microstructure where the pearlite content in the two different samples. Samples A with higher levels of pearlite have a lower corrosion resistance than samples B due to micro-galvanic effect between ferrite and cementite in pearlite microconstituent. The results show that the higher levels of pearlite have lower corrosion resistance. In addition, there are differences in the levels of the chemical composition of small levels of alloying elements such as sulfur, manganese, chromium, and copper may be added to the steel. However, differences in levels of these alloys is not so decide because the levels are very low alloy added. |
