How to solder stainless steel

According to popular belief, it’s too hard to solder a stainless steel. But this operation will be simple, given the helpful tips.

Welding stainless steel with their own hands

Welding stainless steel with their own hands.

Preparation of equipment and materials

The following tools and auxiliary materials are necessary for the soldering of a stainless steel:

  • electric soldering iron;
  • gas-burner;
  • solder;
  • flux;
  • metal brush;
  • solvent;
  • soap;
  • rags;
  • protective gloves.
Stainless Steel Performance Chart

Table of characteristics of stainless steel.

The power of an electric soldering iron should be 100 watts, in extreme cases - at least 60 watts. The low wattage device will not be able to heat the steel parts to the optimum temperature. A soldering iron of greater power is required when it is necessary to connect products of large sizes. It is desirable that he had an unburned sting. Such a device is more durable, it is faster and more convenient to work with it.

But the technical capabilities of the soldering iron are limited by two circumstances. First, it warms up only soft, low-melting solders. Secondly, it is impossible for them to solder parts with a high degree of heat dissipation. Since the temperature of the soldering tip is dictated by the type of solder, it is necessary that it be amenable to melting. So, for example, solid brass solder will not succeed in melting with an ordinary soldering iron. In such cases, a gas burner is required. Although this somewhat complicates the soldering procedure, the use of a torch in the form of a compact gas cartridge is quite acceptable.

Modes of welding inert gas

Modes of welding in inert gases.

Choosing a solder, many prefer the bars of the PIC series from tin-lead alloy. The most popular brands are "POS-40", "POS-61". Solder "POS50Kd18", containing, in addition to tin and lead, cadmium, is especially good for soldering chips, which can not be overheated.

Solders with zinc melt easily, but are practically unsuitable for working with low-alloyed and carbonaceous steel: they stick to it poorly, quickly flow into the gaps and give loose connections. Best of all, stainless steel is soldered with pure tin. Only tin solder can be used for the repair of products in contact with food.

Soldering steel parts will not succeed using habitual rosin. It is good for copper, and for stainless steel you need an active flux - orthophosphoric or soldering acid (zinc chloride). Inflicting such a flux, immediately proceed to soldering. This is especially important when using orthophosphoric acid, because literally in a matter of seconds a phosphate film forms on the surface of the steel and soldering becomes difficult.

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Soldering technology

Welding stainless steel semi-automatic

Welding stainless steel semi-automatic.

First, brazed steel parts must be cleaned from both impurities and oxide film. This is usually done with a metal brush, sandpaper or grinding wheel. Then they should be degreased with acetone or any other solvent. After that, flux should be applied to the places of the future connection of parts (unless, of course, the combined solder already covered with it is used).

Further it is required to heat them either with a soldered iron tip or gas burner. It is important that there is no excess oxygen in its flame, otherwise the metal will oxidize. Normally, it should have a bright blue color. If the flame is weak and pale blue, then it is saturated with oxygen.

Moving the burner smoothly, heat the entire connection. Periodically you need to touch it with solder to find out if the required temperature has been reached. This can be judged when the solder begins to melt, but not from the flame of the burner, but from the red-hot metal.

Then you need to immediately put the solder in the joint area, continuing to heat the parts so that the solder melts and gradually fills the entire joint. If the liquid solder is not enough in some place, it should be heated more strongly, and he will rush to this place. A sign of solid soldering is the leakage of excess molten solder from the seam gaps.

If the designs of the soldered parts allow, it is advisable to first solder them in places of future contact with solder, and then connect and heat to its melting temperature. With this method, the compound usually achieves greater strength. It does not matter if not the entire surface of parts will be tainted from the first time. It is necessary to reapply the flux to unsuccessful places and reheat them with a soldering iron or a burner. This procedure is repeated until all surfaces of the parts are covered with a uniform layer of solder.

Soldering sheet steel inset is especially necessary for various tin work, repair of car bodies. You can connect them not only by the method of pre-tinning, but also with the help of solder paste, in which the solder is combined with the flux. She needs to cover the contact area of ​​one of the prepared parts, then fix them with clamps and heat the seam on both sides.

It has its own characteristics of brazing (see video), for example, brass. As a flux used drill. It is necessary to warm up parts longer and stronger, as brass melts at a temperature of 1000 ° C.

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Why soldering may not work?

If the solder does not want to be evenly distributed over the surfaces of the parts, then an error is made.

Table of types of electrodes for welding stainless steel

Table of types of electrodes for welding stainless steel.

It often happens that they are not thoroughly cleaned. Often, soldering begins when the surfaces of the products are still poorly heated, especially if they are large in size.

Perhaps the wrong choice for stainless steel solder and flux. For example, pure lead - instead of tin or POS alloy, or rosin - instead of solder acid or borax. Working with tin is difficult because of its insufficient consistency. The molten tin should not resemble soft clay, but liquid, otherwise it will crumble or bubble.

If you do not allow such errors, the soldering will be uniform and high-quality. Solder can be scratched, but it will not be possible to separate it from the stainless steel. So strong is the resulting seam.

After the soldering is completed, allow the product to cool. It should not be at this time touch, move. Then it will be necessary only to clean the product from solder residues, flux and wash with soap.

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