Causes of Brittle Fracture in Square Tubes

The acid pickling process for square tubes involves the use of a mixture of acids, including sulfuric acid, nitric acid, and hydrofluoric acid.

The acid pickling process for square tubes involves the use of a mixture of acids, including sulfuric acid, nitric acid, and hydrofluoric acid. These acids have strong corrosive and oxidizing properties, and they operate at relatively high temperatures, demanding high corrosion resistance from the materials.

Among the corrosion-resistant materials suitable for square tubes, epoxy resin and its modified resins are considered the most effective. The acid pickling principle aims to remove oxide layers and metal ions from the surface of the square tubes after pre-treatment, resulting in a smooth and clean surface.

Brittle fractures occur due to various factors, such as precipitation at grain boundaries or segregation of inclusions, which can cause cracks regardless of their strength relative to the base material.  Additionally, even under alternating loads well below the yield limit, fatigue fractures can occur.

In the case of low-stress brittle fractures in high-strength metal materials, the material structure is typically non-uniform and anisotropic. Proper cleaning methods, such as using Q345B square tubes to clean rusted pipe fittings, ensure their long-term service in production, thus maximizing production efficiency.  Moreover, alloy tubes should ideally have finely processed surfaces to minimize the risk of brittle fracture.