How to judge whether the TY125-5.5-35.5 reducer gear has heat treatment burns during visual inspection

Whether there are heat treatment burns on the gear of the reducer is mainly determined by methods such as surface color change, acid corrosion detection, and microstructure analysis. Visual inspection can preliminarily identify obvious burns. During visual inspection, if there is uneven tempering color (light brown, dark brown, purple black) or blue or black areas on the surface of the gear, especially in the sliding direction of the tooth surface or the starting area of the tooth root/tooth top meshing, it may indicate the presence of grinding burns. This is because the instantaneous high temperature during the grinding process causes changes in the surface metal structure, which results in oxidation discoloration after cooling. However, it should be noted that minor burns may not show significant color changes and may be easily missed by the naked eye.

1. Acid corrosion detection: After cleaning, the gears are subjected to acid corrosion treatment (such as nitric acid+methanol solution corrosion), and the burn area will show abnormal coloring - the secondary quenching area will be light gray to white, and the tempering area will be dark brown to black, which is significantly different from the normal uniform gray, and can determine the burn location and grade (A, B, D, E grade).

2. Metallographic examination: Observing whether there are abnormal structures such as secondary quenched martensite or tempered martensite on the surface is the gold standard for determining burns.

3. Hardness testing: Burn areas are often accompanied by a decrease or uneven distribution of surface hardness, which can be verified with the assistance of a microhardness tester.