{"id":164,"date":"2018-11-08T17:11:10","date_gmt":"2018-11-08T16:11:10","guid":{"rendered":"https:\/\/www.vecom-group.com\/en\/?page_id=164"},"modified":"2021-03-29T11:29:08","modified_gmt":"2021-03-29T09:29:08","slug":"pickling-passivating","status":"publish","type":"page","link":"https:\/\/www.vecom-group.com\/en\/metal-surface-treatment\/pickling-passivating\/","title":{"rendered":"Pickling and Passivating"},"content":{"rendered":"
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The most important treatment against (corrosion) damage<\/h2>\n

As a result of heat input, for example during welding, a discoloration due to oxidation of the material occurs and an excess of chromium oxides are created. This local excess of chromium oxides offers considerably less resistance to local corrosion (chloride pit corrosion).<\/p>\n

In addition, there are countless sources to cause foreign iron contamination of the stainless steel surface. For example as a result of sanding, grinding, setting and the like with material (tools) made of carbon steel or tools that are also used for machining carbon steel.<\/p>\n

Contamination also often occurs during handling and transport of the material. Therefore, pickling and passivating is important.<\/p>\n<\/div>\n<\/div><\/div><\/div><\/div>

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Pickling and passivating<\/h2>\n

Pickling and passivating removes welding discoloration, annealing skin, foreign iron, restores corrosion resistance and brings it back to the original level of the base material.<\/p>\n

Pickling can be carried out in various ways, depending on the size and construction of the object or part to be treated:<\/p>\n

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  1. Immerse in, or circulate with a pickling liquid;<\/li>\n
  2. Applying a pickling paste, for locally pickling weld seams for example;<\/li>\n
  3. Spraying with pickling spray, a sprayable pickling paste for the quick and economical treatment of large surfaces.<\/li>\n<\/ol>\n<\/div>\n<\/div><\/div><\/div><\/div><\/div><\/div>
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    Passivating<\/h2>\n

    There are quite a few misconceptions about the passivation of stainless steel. After pickling and completely removing oxide skin \/ impurities, stainless steel spontaneously passivates to the air.<\/p>\n

    The quality of the rinsing water is a prerequisite for good passivation. The use of demineralized water is preferred. After rinsing, a full passive state of the stainless steel is obtained after 24 hours. We process the waste water<\/a>\u00a0in accordance with regulations.<\/p>\n<\/div>\n<\/div><\/div><\/div>

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    Chemical passivation<\/h2>\n

    We recommend chemical passivation if it is not possible to rinse with good quality water or if the object \/ component does not have the opportunity to passivate to the air in a clean atmosphere. There has never been any difference in the quality of oxide skin between chemical passivation and natural (to the air) passivation. However, the passivation time is considerably shortened by chemical passivation.<\/p>\n<\/div>\n<\/div><\/div><\/div><\/div>

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    Corrosion problems with stainless steel due to manufacturing and processing<\/h3>\n