There are many welding techniques, including TIG and MIG welding. So what are they and what are the applications to stainless steel welding? Let’s find out now with DAI DUONG
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What’re concept of TIG and MIG:
Firstly, let’s learn the concepts of TIG welding and MIG welding to get an overview and the most basic of these two common welding methods.
What is TIG Welding?
TIG (Tungsten Inert Gas) welding is an arc welding with a non-melting electrode in a protective gas environment. These protective gases are helium or argon, argon combined with helium, argon combined with hydrogen or oxygen.
TIG welding is done by bringing one end of the tungsten electrode close to the other electrode end attached to the material welded. The process of producing arcs and melting welding rods helps to cement the welds. This weld is protected by inert gas, which is the gas mentioned above.
What is MIG welding?
MIG (Metal Inert Gas) welding is a fusion arc welding in a protective gas environment. The protective gases are Argon, Helium or Argon combined with Helium, CO2; CO2 + 02; C02 + Argon … helps pushing air out of the welded area. MIG welding is done by supplying molten electrode, arc and molten metal protected by inert gases.
Differentiate between TIG and MIG welding techniques
TIG welding and MIG welding have different characteristics, advantages and disadvantages as well as applications.
TIG WELDING |
MIG WELDING | ||
| Characteristics | The electrode does not melt.
– Do not use soldering or additives not being able to create slag. – Easy to observe and check the arc. – High temperature |
– Electrodes are molten– Use a welding gun to melt metal, recrystallize into a weld.
– Electric current and arc are maintained automatically by the machine, welding speed, electrode angle are maintained by the mechanic. |
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| Advantages |
– Welding both thin and thick metal, adjustable welding parameters from several amps to several hundred amps.– Welding many metals and alloys. – beautiful quality of clean welds, no dullness, no sediment and controlling the shape of welds as you like |
– High productivity, 2.5 times higher than manual arc method.– Welding with metals such as steel, aluminum, stainless steel … – Not generating toxic during arc process. – Temperature focuses on a certain area. – good quality of welding, less bent, warping. – Save energy, labor time – Welder does not need high skills. |
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| Disadvantages | Productivity is not high
– Requirements on skill, experience and skill of the welder – Because the materials, equipment or devices for TIG welding are expensive -> TIG welding products are often expensive, large quantities are not competitive compared to other welding methods. |
– Productivity is not high– Requirements on skill, experience and skill of the welder – Because the materials, equipment or devices for TIG welding are expensive -> TIG welding products are often expensive, large quantities are not competitive compared to other welding methods. |
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| Materials, equipment for TIG welding | Welding machine, welding gas, welding power source.
– Steel alloys such as stainless steel, carbon steel, black steel. – Other alloys such as copper, aluminum, magnesium, nickel, cast iron … – Welding needles: Based on welding materials to select the appropriate welding needle. Welding needles with a red head (for welding iron and steel), a welding needle with a green head (for welding aluminum) |
– Welding machine, welding gas, welding power source.– Steel alloys such as stainless steel, carbon steel, black steel. – Other alloys such as copper, aluminum, magnesium, nickel, cast iron … – Welding needles: Based on welding materials to select the appropriate welding needle. Welding needles with a red head (for welding iron and steel), a welding needle with a green head (for welding aluminum). |
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| Applications | – Welding of non-ferrous metals and high-alloy steels
– Welding in the field of aviation and aerospace production which requires professional welding techniques, sophisticated and quality welding. – applied to make products of shipping industry such as oil pipe, gas pipe … – Repairing damaged equipment, restoring and reproducing difficult products or on difficult welding alloys such as aluminum or magnesium. – Welding small, difficult, complicated welds in machine parts such as air-conditioners, X-ray machines, projectors, photocopiers … |
– Welding ordinary steel, stainless steel, heat-resistant steel, aluminum alloys, magnesium, copper, nickel …– Welding household products such as tables, chairs, shelves, cabinets, motorbikes, bicycles … – Details in the shipbuilding industry, automobiles, mechanical parts … – Application assembled on robots. |
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How to weld stainless steel using TIG welding method?
There are many techniques for stainless steel welding such as TIG welding, spot welding, MIG welding. However, because of the characteristics of stainless steel, the choice of TIG welding is considered optimal to ensure the best welding quality, without warping or dulling.
The necessary steps for stainless steel welding by TIG welding
Step 1: Prepare stainless steel materials before welding
Clean all stainless steel materials before welding. If the impurities remain on the surface, when welding, it is easy to leave pitting or crack welds. Remove dirt, impurities on the surface of stainless steel with a wire brush, wipe oil with specialized solvent to ensure the cleanest surface.
Step 2: Select the appropriate protective gas
The most suitable protective gas when welding TIG with stainless steel materials is usually Argon or has a high proportion of argon (Argon 75% + CO2 25%).
As for 316 stainless steel, it is advisable to choose a protective gas mixture with a proportion of 90% Helium + 8% Argon + 2% CO2.
Step 3: Apply TIG welding technique on each specific type of stainless steel product
Welding thin stainless steel pipes
With 2 straight pipes in succession:
- Chamfer pipe edges to minimize openings. The greater the gap between the 2 pipes, the easier it will be to overflow the arc into the tube when welding.
- Weld 4 welds into 4 cross-shaped corners. Continue welding dots around the tube. Can use or not use a compensator if the stainless steel thickness is too thin.
- Use offset rods and continuous welding with ziczac welding torch or saw blade for stainless steel materials is not very thin. Current use about 95A – 100A.
With 2 304 stainless steel tubes forming a certain angle:
- Cutting pipes in required curves must be very standard in order to limit the openings when two pipes are joined together.
- Fix 2 tubes with welded joints. Then applying the same welding technique with 2 straight pipes.
It should be noted that because the material is tubular, it is easy to leak when welding or to leak arc into the inside of the pipe wall.
Welding 2 stainless steel armor plates on a flat surface
- Cutting the workpiece and sharpenning the edges so that it is smooth, clean and flat.
- Solder some welds to fix.
- 2T Welding: it applies to thick materials, welds that do not require high sophistication. It is necessary to hold the trigger to keep the arc burning continuously during welding. Worker let the torch groove 80 degrees to easily observe the weld, press repeatedly on the welding line.
- Pulse welding: adjust the pulse as required and the arc will burn continuously according to that pulse. Welding is similar to 2T and does not require continuous interrupting.
Welding 2 stainless steel plates perpendicular
- With stainless steel is too thin: welding press interrupts as the above methods
- With very thin stainless steel: apply picket welding (can use with or without stick)
Top 3 stainless steel welding machines worth using today
Inox welding requires not only good technique and workmanship, but also TIG welding machines that are suitable for maximum weld quality, optimal performance and performance. The best TIG welding machines for stainless steel today:
1/ TIG Weldcom VTIG S200
Technical data:
10A – 200A – 43V
Display: Yes
Capacity: 4.8KVA
Made in Viet Nam
Accessories: 4m welding gun + 3m mass clamp
Warranty 12 months
Price: VND 4,130,000
The welder can weld stainless steel materials from 0.5 – 8mm, with a warning when over current. This makes the machine more durable and safe to use for workers. The machine meets IP21S resistance to dust and water, insulation degree F.
2/ TIG 200A
Technical data:
10A – 200A – 70V
Display: Yes
Capacity: 7KVA
Made in Viet Nam
Warranty 12 months
Price: VND 4,350,000
The welding machine has a welding rod with a diameter of 1.6 – 3.2 mm so it can be varied, fast, suitable for many requirements, beautiful and quality welds. The casing has a waterproof structure. Machine compact, easy to manipulate, move, safe to use.
3/ Inverter Btec TIG/MMA 215 Pro
Technical data:
20A – 215A – 56V
Display: Yes
Capacity: 7.1KVA
Made in Japan
Warranty 12 months
Price: VND 2,200,000
TIG welding machine with Japanese brand (made in China), cheap price should be used heavily in stainless steel welding, easy to arc, beautiful weld. The machine has Inverter technology to save more power, reduce costs for the factory.
Hopefully the article will help readers understand the concept and distinguish between Tig welding and Mig welding. and Tig welding machine is the perfect choice for stainless steel welding.
Soure: Stainless Steel Dai Duong