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Multi-Process Welders

27 February, 19 10:08 am · Leave a comment · wpdude
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Most people who have been in a technical profession know the constant need for a variety of tools.  One minute you may need a pliers, then a knife, then a file, then a screwdriver, and once the day is all done, a bottle opener.  This is the reason why multi-tools have become so popular; they combine all of these tools into one. In the world of welding, there is something similar to a multi-tool.  It is known as a multi-process welder. Red-D-Arc carries multi-process welders because we know that one minute you might be self-shielded flux core welding some dirty, ½” thick steel and then the next minute be fitting up 18 gauge aluminum that you need to gas tungsten arc weld.

Red-D-Arc provides a wide variety of multi-process power sources to suit many customer needs.  The Miller XMT is a type of multi-process welder that Red-D-Arc carries.  All XMT variations provide the capability to MIG, TIG, flux core, and stick weld.  The Field Pro series also possesses Miller’s proprietary pulse waveform known as Regulated Metal Deposition (RMD).

This is a pulsed short arc MIG welding process that is excellent at bridging wide gaps that can result from poor fit-up.

Red-D-Arc is aware that multi-process welders aren’t always operated in ideal conditions.  Extreme heat and environments with high amounts of dust can destroy welding power sources. That is why Red-D-Arc provides the EX360.  The “EX” is for extreme, because this power source can handle extreme conditions.  If protection from dust and heat are a concern while using multiple welding processes, the EX360 may be your solution.  The EX360, as well as several other multi-process welders offered by Red-D-Arc, are available in four-pack and six-pack configurations to enable increased productivity.

Submerged arc welding is an excellent process to achieve high deposition rates, and Red-D-Arc has them. However, some applications require additional welding processes besides just submerged arc welding. When this is the case, Red-D-Arc also has multi-process submerged arc welding machines.  The DC1000, for instance, provides end users with the ability to not only submerged arc weld, but also provides stick, MIG, and flux cored arc welding capabilities.

For additional information on Red-D-Arc’s multi-process welding product offerings, visit our multi-process welder page.

Welding Stainless Steel – Hints and Guidelines

15 January, 19 2:52 pm · Leave a comment · wpdude
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Welding of Stainless Steel

Stainless steel contains a minimum of 10.5% chromium which imparts it corrosion resistance by forming an oxide layer on the surface. The most common stainless steel is the austenitic type (300 series) which contains chromium and nickel as alloying elements. Other types include ferritic, martensitic and duplex stainless steels. Most stainless steels are considered to have good weldability characteristics. Most common processes used for welding stainless steel are TIG (GTAW) and MIG (GMAW). But, stick welding (SMAW) is also utilized.

Differences in Properties:

The properties of stainless steel differ from mild steel, and these differences need consideration when welding as below:

  • Higher coefficient of expansion, 50% more for austenitic – this results in more distortion
  • Lower coefficient of heat transfer – welding requires lower heat input as it is conducted away slowly
  • Lower electrical conductivity – using the correct and consistent stick-out distance is more critical when using MIG/TIG, higher wire speed for the same current is required when MIG welding

Why segregated work area?

Welding of stainless steel is carried out in a work area segregated from carbon steels. Moreover, tools dedicated for use with stainless steel must not be used to work on carbon steels. These tools include brushes, hammers, clamps, grinders etc. The segregation of work area and tools safeguard the contamination from carbon steels, which may cause welding defects and corrosion (rust) on stainless steel. You must also wear gloves when working with stainless steel as this will prevent oil from the hands passed onto the stainless steel.

Preparation is key!

With stainless steel, it is important that the joint surfaces are thoroughly cleaned before welding to remove any dirt, grease, oil etc. The filler wire also needs to be completely clean.

Additionally, the joint design including the joint gap must cater to the higher expansion rate of stainless steels.

Filler Material Selection:

Filler materials used generally are the same as the base metal. Special considerations are required to select a filler material if welding dissimilar stainless steels or stainless steels where no identical filler material exists. Furthermore, filler materials are selected to reduce the risk of intergranular corrosion and hot cracking.

Welding Considerations:

It is essential to protect the weld during welding using a mainly inert gas. Additionally, the weld root needs to be purged using a pure inert gas.

When welding austenitic stainless steels, it is important to restrict the heat input to a level which is just sufficient to ensure a good weld. The interpass temperature is limited to 350 F. Preheating is not carried out on austenitic stainless steels. Very low carbon grades (suffixed with L e.g. 304L, 316L) are used to prevent the formation of chromium carbides in the heat affected zones which causes intergranular corrosion.

Martensitic stainless steels are generally used as wear resistant materials in overlaying applications. To avoid cracking, accurate preheat needs to be applied and a minimum interpass temperature maintained.

Ferritic stainless steels are used mostly in automotive applications. The heat input in these steels during welding needs to be limited, and a maximum interpass temperature of 300 F is recommended. This will ensure that the grain growth in the material is controlled and the strength is maintained.

With duplex stainless steels, the heat input also needs to be restricted.

Cleaning and Passivation:

Stainless steel welds must be cleaned and passivated after completion to ensure corrosion resistance and good appearance. This is performed manually by mechanical (brushing, grinding, blasting), chemical (applying pickling agents and other chemicals) or electrochemical means.

Red-D-Arc has a wide range of equipment suitable for stainless steel welding for rent including the following:

Multi process welders capable of stick, TIG, MIG, submerged arc, air carbon arc cutting, flux core, up to 1500 A

MIG welding units up to 750 A

TIG welding units up to 750 A

Stick welding units – up to 625A

Also 4 and 6 Paks of welders available

Orbital welders – suitable for stainless steel pipe/tube welding

Various brands including Miller, Lincoln, Red-D-Arc

Have a look at our complete range of welding products.

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