Metallurgical and Mechanical Failure Analysis of an Aftermarket Flywheel

A failure analysis investigation was performed on the remnants of an aftermarket gray cast iron flywheel that catastrophically fractured during operation in a vehicle after 24 miles of operation. Light microscopy, 3D X-ray micro-computed tomography (micro-CT), scanning electron microscopy (SEM), metallography, and hardness/tensile testing techniques were utilized to characterize manufacturing quality, mode(s) of failure, microstructural variation, fracture surfaces, and mechanical properties of the failed component. Light microscopy examination of the remnant surfaces showed that the flywheel shattered with signs of radial heat checking fissure cracks. A metallurgical examination of the flywheel showed that it was manufactured from cast gray iron, with evidence of microstructural changes near heat-affected zones from graphite flakes in a ferrite/pearlite matrix to needle and lath formations similar to bainite or martensitic phases. The CT scan slices and fracture surface examination in the SEM showed signs of porosity and dendritic formations along a fracture surface believed to be the crack initiation location. The analysis suggests manufacturing flaws found within the flywheel were a likely contributing factor leading to premature failure during service.

CENTRI-CAST GRAY IRON 50

CENTRI-CAST GRAY IRON 50 is a centrifugally cast gray iron with a nominal tensile strength of 50,000 psi. It is cast in the form of tubing which has a wide range of uses in applications where size and shape are of paramount importance and freedom from pattern cost is an important consideration. Among its many applications are farm machinery, seals, bushings, machine tools and general machinery uses. This datasheet provides information on composition, physical properties, microstructure, hardness, elasticity, tensile properties, and compressive and shear strength as well as fatigue. It also includes information on casting, heat treating, machining, and surface treatment. Filing Code: CI-51. Producer or source: Federal Bronze Products Inc..

CENTRI-CAST GRAY IRON 45

CENTRI-CAST GRAY IRON 45 has a nominal tensile strength of 45,000 psi. It is gray iron cast centrifugally in the form of tubing which has a wide range of uses for applications where freedom form pattern cost is an important consideration and where size and shape are of paramount importance. Its many applications include automotive equipment, farm machinery, bushings and machine tools. This datasheet provides information on composition, physical properties, microstructure, hardness, elasticity, tensile properties, and compressive and shear strength as well as fatigue. It also includes information on casting, heat treating, machining, joining, and surface treatment. Filing Code: CI-50. Producer or source: Federal Bronze Products Inc..

CENTRI-CAST GRAY IRON 55

CENTRI-CAST GRAY IRON 55 is a centrifugally cast gray iron with a nominal tensile strength of 55,000 psi. It is produced in the form of tubing which has a wide range of uses in applications where size and shape are of paramount importance and freedom from pattern cost is an important consideration. Typical applications are seals, bushings, farm machinery, casings and general machinery uses. This datasheet provides information on composition, physical properties, microstructure, hardness, elasticity, tensile properties, and compressive and shear strength as well as fatigue. It also includes information on casting, heat treating, machining, and surface treatment. Filing Code: CI-48. Producer or source: Federal Bronze Products Inc..

CENTRI-CAST GRAY IRON 30

CENTRI-CAST GRAY IRON 30 is a centrifugally cast gray iron with a nominal tensile strength of 30,000 psi. It is produced in the form of tubing which has a wide range of uses for applications where freedom from pattern cost is an important consideration and where size and shape are of paramount importance. This datasheet provides information on composition, physical properties, microstructure, hardness, elasticity, tensile properties, and compressive and shear strength as well as fatigue. It also includes information on casting, heat treating, machining, and surface treatment. Filing Code: CI-46. Producer or source: Federal Bronze Products Inc..

CENTRI-CAST GRAY IRON 40

CENTRI-CAST GRAY IRON 40 is a centrifugally cast gray iron with a nominal tensile strength of 40,000 psi. It is produced in the form of tubing which has a wide range of uses in applications where size and shape are of paramount importance and freedom from pattern cost is an important consideration. Typical applications are automotive equipment, compressors, machine tools and general machinery applications. This datasheet provides information on composition, physical properties, microstructure, hardness, elasticity, tensile properties, and compressive and shear strength as well as fatigue. It also includes information on casting, heat treating, machining, and surface treatment. Filing Code: CI-44. Producer or source: Federal Bronze Products Inc..