Titanium alloys are widely used in civil applications due to their excellent properties, high specific strength, good temperature performance, and non-magnetic properties.The titanium alloy products developed almost permeate every aspect of modern life.In the production, we found that the surface quality of titanium alloy products common faults are over corrosion, ash, oxide skin and stripes.

1. Over-corrosion: Over-corrosion refers to the appearance of pitting or bump inequality defects on the surface of titanium alloy after pickling, which is different from the exposure of material tissue.Generally, the cause of over-corrosion defect is the imbalance between hydrofluoric acid and nitric acid, which can be caused by high concentration of hydrofluoric acid or insufficient concentration of nitric acid. Another reason is that the pickling time is too long. Generally, the pickling t is 1mm ~ 4min, and the process parameters can be adjusted according to the operation site to appropriately shorten the pickling time.

2. Hanging ash: Hanging ash refers to the oxide attached to the surface of titanium alloy after pickling. During pickling, the dry titanium alloy reacts with the acid, and the oxide generated accumulates on the surface, preventing the further occurrence of the reaction.The defects of hanging ash are generally caused by too much ash deposition during pickling and insufficient washing after pickling.During pickling, parts should be shaken constantly to make the reaction product fall off from the surface of titanium alloy. After pickling, it is necessary to strengthen the method of spraying or washing to remove hanging ash.Domestic generally adopt compressed air and tap water mixed high - speed water washing parts, the effect is good.

3. The oxide scale is not completely removed: there are many reasons leading to the defect, and all processes are possible.There may be poor oil removal, or insufficient molten salt treatment time, or pickling solution failure.When this defect occurs, all possible factors should be excluded one by one. If necessary, sandblasting process can be added before treatment.

4. Striped spots: The cause of this defect is generally caused by uneven response.This can be removed by shaking parts during pickling and by lowering the temperature of the pickling solution.In addition to the above several defects, sometimes also found after pickling qualified products, after a period of time, the surface of the phenomenon of spots.For this kind of phenomenon, research is less now, may be due to the acid pickling surface of residue after acid corrosion medium or subsequent production into existence, under the joint action of stress, under the micro test and general corrosion morphology, generally does not affect its using performance, through pickling method to remove again, but after the stress thing to strengthen the secondary pickling except hydrogen treatment.