Can high temperature of brake discs cause brake disc failure

       Short term temperature rise of brake discs is a normal phenomenon, but prolonged high temperatures exceeding the material's tolerance limit can indeed cause brake discs to "fail", mainly manifested in the following four paths, which often occur in combination:
          Fade
          After the temperature exceeds 350 ℃, although the cast iron disc body will not soften, the friction materials such as resin and metal fibers on the surface of the brake pads begin to decompose, and the friction coefficient drops sharply by 30% -60%. The braking force "disappears out of thin air" and the pedal stroke becomes longer. This is a common phenomenon on racetracks or long downhill slopes where "even if you step on it to the bottom, you cannot stop it".
          Disk deformation and microcracks
          When the peak temperature is greater than 500 ℃ and the heat dissipation is insufficient, the temperature difference between the inner and outer edges of the disc exceeds 120 ℃, and uneven thermal expansion leads to conical deformation or local bulging of the disc; Continuing to heat up to above 600 ℃, microcracks will form due to the expansion difference between the cast iron matrix and graphite. After multiple cycles, the cracks will propagate, resulting in "shaking+abnormal noise" and the possibility of sudden fracture at any time.

          Brake fluid "air resistance"
          The high temperature is transmitted to the cylinder through thermal conduction, and the DOT4 brake fluid can vaporize at a temperature of ≈ 230 ℃, producing compressible bubbles. When the pedal is stepped down, the system pressure cannot be established, which is equivalent to completely losing the hydraulic amplification effect.
          Material oxidation and strength degradation
          In heavy-duty vehicles or track environments, the disc temperature can exceed 800 ℃. The cast iron matrix reacts with oxygen to generate oxide scale, and oxidation channels are formed between graphite particles, becoming a source of thermal fatigue cracks, reducing bending strength by 20% -40%, and shortening the service life to one-third of the original.
          Daily road driving is generally safe within 400 ℃ for short periods of time; If the temperature continues or repeatedly exceeds 500 ℃, it will enter the "failure countdown". Once you notice that the pedal is soft, the steering wheel is shaking, or there is a blue purple oxidation color, you should immediately stop and forcefully dissipate the heat, and check whether the disc is deformed or cracked. Otherwise, the next heavy brake may completely fail.