Today, the most effective and efficient way to connect two metal products is welding. The principle of operation of this device is very simple: it emits a flame, which by its high temperature melts the metal and brings it to the state when interatomic bonds begin to manifest. In order to leave objects in their original form and not to spoil their shape, use electrodes, they help melt the product and connect them together. Different welding methods are used for different types of welding and for different materials. But what types and modes of welding should be used to know what to weld stainless steel? To do this, you need to know how it differs from other types and what it is.
Diagram of the process of welding stainless steel semi-automatic.
The main differences and advantages of stainless steel
Cooking stainless steel is becoming increasingly popular due to its excellent quality indicators. These characteristics allow you to make welding much faster and more convenient, unlike other metal products. For example, this type of metal is very good for making tanks for domestic water supply, which will store the necessary supply of water at home. A lot of people at the moment are using plastic for this purpose, but, as you know, its chemical effects can affect water quality and human health.
Despite the fact that plastic is a bit cheaper than a stainless steel tank, a large number of people give their preference to the second. Since many people want to have good health, truly reliable things, stainless steel remains relevant to this day. From the name it is clear that this type of metal is protected from corrosion by its special composition. In order for a tank filled with water to rust, it will take more than one hundred years for it to become tempting to use.
Composition and mechanical properties of different grades of stainless steel.
When the metal is not rusty, welding is greatly facilitated, as it does not have to clean the object before starting to cook. But it is still necessary to do the cleaning work from other types of dirt and spraying. It is worth noting that ordinary carbon steel undergoes a welding process much easier than stainless steel. This is due to the special composition of the steel, which differs from the usual such characteristics:
- does not have a large resistivity;
- in the process of welding there is a very strong thermal expansion;
- this metal has a low melting point;
- composition gives greater thermal conductivity.
The use of electrodes to weld stainless steel
If we talk about domestic realities, it is best to use the electrodes OZL-6 and OZL-8, which are better suited for welding stainless steel than argon. In addition, their availability is a big plus, as they are always available in stores selling welding equipment and electrodes to them. Electrodes such as MP-3 and OK 46.00 can be used. Of course, other electrodes are also able to perform this task, but these types will be able to do the welding with the highest quality and facilitate your work.
The scheme of the electrode for welding.
You will get a seam with excellent performance. But besides all the positive characteristics, before using these electrodes you should be familiar with the basic safety rules. After welding has been performed and the weld begins to cool, all the excess materials selected in the process begin to bounce due to the large heat.
This factor can be very useful, since you do not have to clean the seam of such materials. All that is required of you is to move away from the material and bounce all the slags. But caution should be exercised, as hot slag can cause serious burns if it gets on parts of the body. In no case should such particles be allowed to hit particularly vulnerable organs, such as the eyes. But if you follow all the precautions when working with a material such as stainless steel, you will get high-quality work, spending a minimum of time and effort. It is best to use welding at a current of reverse polarity and perform work in the lower position of the seam.Back to table of contents
Methods and methods of welding stainless steel
In the case when you need to do welding in 1.5 mm, you should use manual arc welding, you will need to use a tungsten electrode in an inert gas. This method of welding is very well suited for joining pipes and thinner sheets made of stainless steel. When the thickness of the metal is 0.8 mm or more, pulsed arc welding is best, in which an electrode to be melted in an inert gas will be used.
Scheme of manual arc welding.
You can try arc welding using jet transfer metal. There is a new plasma welding. This type allows you to weld stainless steel sheets that are thicker. If the stainless steel sheets are thicker, submerged arc welding or spot and roller welding will work. This will allow you to achieve high quality bonding and not too distort the material.
The preference for the lower position of the seam is due to the fact that in the process of cooling this seam can cause damage to your health. In the case when you still have to do overhead welding, it is best to protect yourself and use some precautions:
- you should wear a welding mask;
- You must have a high-quality holder for the electrode, which will protect your hands from burns;
- should wear a special welding suit that can protect against unforeseen circumstances.
It must be remembered that even with full equipment it is best to move away from the cooling seam when working with stainless steel.Back to table of contents
Seam processing after stainless steel welding process
Scheme of manual arc welding.
After welding has been performed, in the place where the material was melted, porous seams will appear. This oxide layer contains chromium. If you do not remove these seams in time, in the future these seams will be most susceptible to corrosion.
In order to process the seams and remove them, a huge number of methods are used:
- Remove the seams with a ground circle and tape.
- You can use a stainless steel brush for this purpose.
- Shot blasting is applied.
But in the case of stainless steel, a method such as pickling is best. This method will allow you to easily remove the unnecessary oxide layer on the metal in the shortest possible time. The method consists in corroding the layer with an acid additive. Apply the mortar in two ways:
- Apply it on the oxide layer.
- Dip a metal product in a special bath filled with a solution of acid and water.
More popular is the second option, when stainless steel is dipped into the bath for some time to corrode the oxide solution.
The time it takes for this solution to completely dissolve the layer will depend on the concentration of acid it contains and on the type of stainless steel used to make the item.