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Because of severe operational conditions, many working components are subjected to complex combination of cyclic temperature & mechanical loading. Premature failure is the major problem encountered in the operation of brake discs. To determine the nature of cracks the failure investigation described in this study was carried out by using different experimental methods as Fatigue tester method, NDT, Bentch study braking equipment, Furnace experimental testing, Chemical Testing etc. In the furnace experimental testing stainless steel specimen with a pre-existing surface notch is exposed to a convective medium of cyclic temperature. In Bentch study, braking equipment wheel-mounted forged steel brake discs are exposed to heavy thermal and mechanical loadings and subjected to high thermal shock loading during routine braking and emergency braking. The present study was carried to develop simple method for studying the crack propagation with the aim of developing brake discs with increased lifespan, so as to improve the safety and reliability of these components.