Heat fatigue test of brake drum

A, sample preparation

A square ingot with a wall thickness of 1.5cm in length and width was cut from the flange base of the failed brake drum, which was not affected by the high-temperature phase transition. The residual stress affected layer of the wire cut surface was worn off (note that no new residual stress was generated during grinding). Finally, all the surface roughness of the ingot was treated to ≤3.2μm.

Two, test operation

The specimen was heated to 880℃ for one minute, then taken out and cooled in water at 20℃ quickly. Such a cycle operation was carried out until cracks were observed by the naked eye. Then the specimen was blown dry and metallographic observation was carried out.

Three, test results

After the test, 30 test blocks in 31, 14, 35, 28, 41, 29, 36, 28, 30, 26, 28, 32, 32, 33, 37, 29, 34, 27, 33, 28, 37, 28, 30, 33, 36, 27, 30, 32, 40, 29, 30 times of high temperature cold crack visible to the naked eye. And the crack pattern is consistent with the failure part of the brake drum.

Four, conclusion

Thermal fatigue fracture caused by high temperature and cold is indeed one of the main reasons for brake drum cracking and cracking.