Abstract
Corrosion is a natural occurrence of metal damage caused by electrochemical interactions with the environment. One of the causes of corrosion is the attachment of bacteria, commonly called biocorrosion, to the material. Biocorrosion can cause a failure on pipe structure which causes the pipe not to operate correctly. The purpose of the research was to determine the effect of the annealing and hardening treatment process on the bio-corrosion rate of API 5L steel. The treatments were, namely, without heat treatment as a control and heat treatment (annealing and hardening process). All specimens without and with the heat treatment were being used on the bio-corrosion test. The bio-corrosion testing was conducted with immersion corrosion test method with artificial seawater salinity of 35‰. Three of species bacteria were be used, Escherichia coli, Pseudomonas fluorescens, and Thiobacillus ferrooxidans. The result showed that bacteria could accelerate the corrosion rate. The decreasing corrosion rate on E. coli with full annealing showed a higher value (17.23%). It reached 2.8367 mpy. Meanwhile, it reached 3.427 mpy at material without full annealing. The decreasing corrosion rate on E. coli with hardening was 3.0506 mpy. It indicated that annealing and hardening treatment could increase biocorrosion resistance.