Why might steel parts have a greater tendency towards rusting after penetrant testing?

Steel parts often have a greater tendency toward rusting after penetrant testing primarily because the protective oils originally present on the steel surface are removed during the cleaning and testing process. During penetrant testing, parts typically go through a series of cleaning steps to ensure that any surface defects can be accurately detected. This cleaning removes not only contaminants and dirt but also any protective coatings or oils that serve to inhibit rust formation.

When these protective oils are removed, the bare steel is exposed to moisture and air, which can lead to oxidation, resulting in rust. Thus, without these protective measures, the likelihood of rust developing on the steel components significantly increases.

While other factors might contribute to the potential for rust, such as the inherent properties of the penetrant materials, the removal of protective oils stands out as a critical reason why rusting risk increases after testing.