Other Products for Stainless Steel
When stainless steel is welded, an area on either side of the weld is heated nearly, but not quite, to the full melting point of the alloy. This high temperature is still sufficient to allow the different metals that make up stainless steel to move around and reorganize themselves, as well as reacting to form oxides and carbides. In this “heat affected zone” the steel loses much of its corrosion resistance and becomes discolored, usually to blue and/or brown.
Passivation of these areas is key to restoring the corrosion resistance, and this can be done with or without the prior removal of the discoloration, oftentimes using CitriSurf 2210.
Removal of the discoloration is often desired in order to give the weld area a cleaner appearance, especially for items that are visible to the public. This can be done using three main methods: Electropickling, Chemical Pickling, and Mechanical Removal.
These products from Stellar Solutions can be used to remove weld discolorations using these methods:
Electropickling, using a combination of chemical and electric current, is a very fast and effective method of cleaning the weld discoloration. This principle is similar to electropolishing, but less refined and directed only along the weld area. There are a variety of commercially available units for this, or a wand electrode can be put together with the welder itself rigged as the current source. Phosphoric acid is often used for this, but Weld Wizard 9003 is a safer alternative.
Chemical pickling traditionally uses a hazardous mix of nitric acid and hydroflouric acid to remove scale, discoloration, and other surface flaws from stainless steel. The hazards to skin contact and fume inhalation make these chemicals difficult to deal with in either bath or paste form, and the potential for etching the metal surface is high. We have developed alternatives that are much less hazardous and have a lower potential for etching, but still do an excellent job at removing most weld discolorations. Weld Wizard 9310 is the paste version for most welds, and Weld Wizard 9350 is a liquid version for immersion of bulk small parts in a bath.
Mechanical removal methods can include wire wheel grinding, sand or bead blasting, and polishing the surface down to blend the weld completely with the surrounding material. Weld Wizard 9700 is an abrasive polish material that can be used to remove weld discoloration when other methods are not viable or the necessary equipment is unavailable.
Contact us with your questions, or to discuss your application. Product samples are available to industrial customers.
Precleaners and Specialty Cleaners
These products from Stellar Solutions are available for precleaning in a passivation line and other specialty applications:
CitriSurf products also show great success in removing tarnish from copper, brass, and bronze. CitriSurf 77 is often used on brass beds and other household items, while products such as CitriSurf 2050 or CitriSurf 2250 can be used to brighten parts in bulk.
KleerKleen 4000 is a safe detergent-based cleaner/degreaser for use when needed prior to passivation in CitriSurf.
KleerKleen 4002 is a caustic alkaline cleaner for use when needed prior to passivation in CitriSurf, especially for stainless steel grades high in sulfur (free machining grades), grades high in carbon, and for the elimination of organic residue in process tanks and pipelines during CIP operations.
CitriSurf 9002 is a safe copper stripper for use on stainless steel parts where a copper coating or copper/brass slag on the surface needs to be removed prior to passivation with other CitriSurf products.