Abstract: In addressing six failure cases involving non-critical pressure metal components in coal-fired generating units and gas-steam combined cycle units of power system, the failure cases were analyzed through a combination of macroscopic observation, material analysis, microstructure analysis, and mechanical property analysis with the service environment of the units. Results show that, the failure locations of components are often found at stress concentrations with abrupt sectional changes, and the main causes for failure are identified as external environmental corrosion and fatigue damage. Misuse of material or inadequate control of production process leads to poor microstructure quality and a decrease in overall macroscopic mechanical properties and accelerates component failure. As non-critical pressure components of the shaft, auxiliary bolts or other equipment in generator sets are not given adequate technical supervision and management attention, leading to significant issues such as the misuse of materials or inferior material quality.