Causes and improvement measures for hydrogen embrittlement of normalizing furnace mesh belts

During the normalizing process of heat treatment, the breakage of the metal mesh belt not only leads to frequent shutdowns, increases maintenance costs, but even affects the production progress. Today, Jiaoyang Mesh Belt will explore with everyone the reasons for hydrogen embrittlement of the mesh belt in the normalizing furnace, ensuring the stable operation of the normalizing furnace.

Precise source tracing: The main causes of hydrogen embrittlement fracture

Hydrogen embrittlement fracture is not accidental but the result of the combined effect of hydrogen atom accumulation and external conditions. Jiaoyang, through extensive case analysis, has found that the core triggers are concentrated in three points:

1. Out-of-control dew point of furnace gas: In pursuit of a bright effect on the workpiece, the dew point is excessively reduced, resulting in insufficient water vapor inside the furnace, which fails to “neutralize” the protective atmosphere. Over time, the accumulation exceeds the critical value.
2. Improper pretreatment of workpieces: If workpieces are not thoroughly cleaned before entering the normalizing furnace, the residual oil stains, cutting fluids, moisture, etc. on their surfaces will decompose and produce a large amount of hydrogen at high temperatures.
3. Poor sealing of equipment: Improper adjustment of the combustion system of the normalizing furnace (such as an inappropriate air/gas ratio, leading to incomplete combustion) will generate a large amount of water vapor and incomplete combustion products, and may also increase the local hydrogen content inside the furnace.

Why did it start to break after a few months?

1.During daily operation, hydrogen atoms constantly enter the steel. Several months of operation is sufficient for the hydrogen content in the mesh belt to accumulate to a dangerous critical value.

2. The mesh belt is constantly subjected to tensile stress and bending stress at high temperatures, which not only provides a place for hydrogen enrichment but also promotes the formation of cracks.

3. The operation of the mesh belt is cyclical and it is constantly exposed to high temperatures, which results in a combined effect of thermal mechanical fatigue and creep.