Although many mechanisms have been proposed to explain the microbiologically assisted cracking (MAC) of steel and copper, a theoretical interpretation is necessary. In this paper, we attempt to give a theoretical interpretation of sulfate/nitrate reducing bacteria (SRB/NRB)-assisted cracking using E^e-pH diagrams. Under the combined actions of SRB/NRB and external stress, the cell potential (E^cell) and the corrosion current density of the corrosion reaction increase, such that the corrosion reactions become more thermodynamically favorable. This is the nature of MAC. Nitrate is a far more potent oxidant than sulfate, and thus, the NRB-assisted cracking of iron is a more thermodynamically favorable process than the SRB-assisted cracking. Furthermore, the thermodynamic interpretation is attempted to implicate into the classical stress corrosion cracking mechanisms of pipeline steel.

尽管已经提出了许多机制来解释钢和铜的微生物辅助开裂（MAC），但仍需进行理论解释。在本文中，我们尝试使用E ^e -pH图给出对硫酸盐/硝酸盐还原细菌（SRB / NRB）辅助裂解的理论解释。在SRB / NRB和外部应力的共同作用下，细胞电势（E ^cell），并且腐蚀反应的腐蚀电流密度增加，使得腐蚀反应在热力学上变得更加有利。这就是MAC的本质。硝酸盐是比硫酸盐更有效的氧化剂，因此，铁的NRB辅助裂解比SRB辅助裂解在热力学上更有利。此外，试图通过热力学解释来解释管线钢经典的应力腐蚀开裂机理。