<p>Safety valves are critical devices that automatically release excess pressure to prevent equipment damage and ensure safety. The spring within a safety valve is particularly important, as it directly regulates the opening and closing of the valve disk; any failure of this spring can lead to catastrophic consequences, including equipment failure, explosions, and serious safety incidents that threaten personnel and property. This investigation was prompted by an unexpected fracture of the spring after about 230,000 fatigue cycles, with the failure occurring near the second coil. A comparative testing of an identical spring model revealed no failures after 300,000 cycles, underscoring the need for a detailed analysis of the fractured spring. Through comprehensive analysis involving visual inspections, chemical composition assessment, metallographic examination, mechanical property testing, and microscopic morphology and component analysis, the study identified that the fracture was initiated by a coarse grain area linked to pit defects in the raw material. These defects arose from ineffective removal of decarburization layers during processing, resulting in diminished hardness and strength. The findings highlight the need for sourcing high-quality materials, implementing rigorous quality control during manufacturing, and improving heat treatment processes to enhance the spring’s mechanical properties.</p>