Microbiologically influenced corrosion (MIC) is the process of material degradation in the presence of microorganisms and their biofilms. This is an environmentally assisted type of corrosion, which is highly complex and challenging to fully understand. Different metallic materials, such as steel alloys, magnesium alloys, aluminium alloys, and titanium alloys, have been reported to have adverse effects of MIC on their applications. Though many researchers have reported bacteria as the primary culprit of microbial corrosion, several other microorganisms, including fungi, algae, archaea, and lichen, have been found to cause MIC on metal and non-metal surfaces. However, less attention is given to the MIC caused by fungi, algae, archaea, and lichens. In this review paper, the effects of different microorganisms, including bacteria, fungi, algae, archaea, and lichens, on the corrosion properties of engineering materials have been discussed in detail. This review aims to summarize all of the corrosive microorganisms that directly or indirectly cause the degradation of structural materials. Accusing bacteria of every MIC case without a proper investigation of the corrosion site and an in-depth study of the biofilm and secreted metabolites can create problems in understanding the real cause of the materials’ failure. To identify the real corrosion agent in any environment, it is highly important to study all kinds of microorganisms that exist in that specific environment.

This study examines how a fast–slow–fast intermediate-cooling schedule redistributes bainitic transformation and hierarchical boundaries in an 800 MPa steel. Among intermediate temperatures of 630, 650, and 710 °C, 650 °C produced the highest tangent-derived first-interval contribution (79.44%). At T_h = 750 °C, a normalized bainite rate index reproduced the schedule ranking (Q_b,eff = 68.58 kJ mol⁻¹; root-mean-square error (RMSE) = 0.0043). Relative to continuous cooling, intermediate cooling increased the first-interval dilation share from 40.6% to 58.7% (+18.1%) and the processed hierarchical high-angle share from 46.9% to 52.2%. A common kernel average misorientation (KAM)–geometrically necessary dislocations (GND) conversion factor reproduced the reported medians within ±0.07%. Mean hole expansion ratio (HER) increased from 53% to 69% (+30.2%), whereas elongation changed by −0.5%. These results establish a process–kinetics–boundary–property pathway in which intermediate cooling shifts the transformation response toward the early interval, enriches high-angle boundary character, and improves local formability while maintaining the tensile-property balance.