3 Metal Prep Tips & Metal Types: Basic Guide

Whether or not a metal is suited for a welding project depends on which elements are being implemented to make the metal finish. It’s crucial to pin the specific kind of metal and which elements are to be joined to increase its:

  • toughness
  • ducility
  • resistance to impact 
  • resistance to corrosion
  • strength(key)

Metals are usually divided into two categories: ferrous and nonferrous.

Ferrous metals have iron as their major element & can be found as forged steel, cast iron , stainless and mild steels. Furthermore, these metals usually have a magnetic property.

Nonferrous metals carry elements that have pure properties.  Aluminum is one of the major nonferrous metals. They do not have an iron property,are always nonmagnetic and have much lower melting temps.

It’s critical that the base & fillers are a match which ensures that like metals are  actually being welded together, with sustainability in mind. Because this process does involve the melting and fusion of the base and filler into one new metal melting temperatures and metal characteristics must be similar. We can join dissimilar metals by brazing, braze welding, or soldering, because these processes do not actually melt the base metal. Ferrous metals contain iron with varying amounts ofcarbon and other alloying elements, such as chromium, molybdenum, manganese, and nickel. Each alloy impartsa unique characteristic to the low carbon steel. Mild steel (low carbon steel) is the most commonly used type and the easiest with which to work. Mild steel can be cut and welded with all of the processes covered in this book. It makes up most of the metal items you commonly use, make, or repair, including automobile bodies, bicycles, railings, furniture, cabinets, and shelving. Adding more carbon to the steel makes it harder but also more brittle and more difficult to cut or weld. These high-carbon steels are used to make cutting tools, such as drill bits, machining bits, and knife blades. Adding other alloying elements, such as chromium and nickel, to the low carbon steel produces stainless steel. Because the stainless steel does not oxidize (rust) easily, it is cut best with a plasma cutter. As always when welding low carbon steel or alloyed steel, the filler metal must be matched to the elements to ensure a high-quality weld is produced. Aluminum is the most widely used nonferrous metal, because it is lightweight and corrosion resistant. Like steel, it is available in many alloys and is often heat treated to increase strength. Aluminum is used for engine parts, boats, bicycles, furniture, kitchenware, and now automobile frames. Various characteristics make aluminum difficult to weld successfully—it does not change color when it melts, it conducts heat rapidly, and it immediately develops an oxide layer that melts at a higher temperature than the base metal itself, causing overheating and extreme distortion and metal destruction.


Metal Structure Shapes

Metals come in a variety of  shapes/dimensions and girth. Metal girth may be shown in fractions , gauges or decimal form.. Sheet metal is typically 316 inch or less in thickness and called out as a gauge number, and plate metal is 14 inch or thicker. Structural metal typically is identified by its length, width, and by its wall, leg, or web thickness. Some of the most common structure types and size callouts are:

Sheet metal

A. Sheet metal usually comes 316” or smaller  in thickness, and is frequently cited with a gauge #. The plate comes 14” or larger in girth, and is nominal in fractional inches.





rectangular tube

B. Rec Tubing

B. Rectangular tubes are utilized  in trailer hitches,  frames, and many kinds of furniture. Rec tubing is nominated by width x height x wall thickness x length.



Square Tubing

C. Square Tubing


C. Square tubes are also used for similar utilizations as with Rectangular tubes. Dimensions are specified the same as Rec Tubing.

Rail Cap

D. Rail Cap

D. Rail Caps are utilized in producing handrails. Rail cap dimensions = Total width + the widths of the channel underside.


E. Channel

E. Channel is typically utilized in also creating specific types handrails. Massive channel can be used in truck chassis, infrastructure in bridges or industrial equipment. The flanges, make it more durable then flat metal bars. Magnitude for channel are measured by flange girth x flange heighth x channel width x length.


Round Tubing

F. Round Tubing

F. Round is dissimilar to pipe tubing. Round tubes are utilized for  structural components but pipe’s main use is transporting certain liquids and gases. Dimensions in round tubing are measured with outside diameter (OD) wall thickness x length.

T Bar

G. T Bar

G. T-bar dimensions are measured as width x height x thickness of flanges x height.



angle iron

Angle Iron

G. Angle Iron has many structural and decorative uses. Dimensions for angle are specified by flange thickness x flange width (leg) x flange height (leg) x length. Angle can be equal leg length or unequal leg lengt


square metal

square metal





H. I. J. Round, Square or hexagonal bar (hex bar) dimensions are specified by width/outside diameter (flat to flat for hexagonal bar)  length.  Flat bar/strap (not pictured) is available in many sizes and is typically not wider than 12″ for flat bar are specified by thickness x width x length.

Round metal

Round metal

Hex bar

hexagonal bar


Metal Preparation

A healthy weld should start with a well prepped welding joint. Cleaning and prepping the welding joint yields a much higher quality weld, so this step should not be overlooked. While using HRS (Hot Rolled Steel) , removal of a thin layer of oxide which forms when the steal is heated(mill scale) is mandatory .Make sure to  clean all parts of the project including ROD( my acronym rust, oil, dust) and the mill scale. This takes time and care but is essential when in wanting quality in your weld projects. With painted or power coated projects , a total cleanse is a must. If parts will be allowed to rust or become aged, thoroughly clean all areas to be welded.

 3 Steps To Take When Cleaning Metal

1| Remove all grease, oil, or dirt by wiping the part down with denatured alcohol, acetone, or a commercial degreaser. phosphoric acid or Alcahol would be our reccomendations. The POR-15 works great for most any metal.

The problem with many acetone and degreaser products is that they form residue splotches that sometimes ruins the final weld quality.

2|Mills Scale must be removed right after ROD is removed. You can do this by wire brushing, grinding, sanding, or sand blasting the part. A bench-mounted grinder with a wire bush works well for cleaning small parts or the ends of smaller parts, but it cannot be used on larger surfaces. We like the Neiko 10207A  3” mini grinder for this task.

Neiko 3" mini

Neiko 3″


For larger surfaces, you will need an angle grinder outfitted with a grinding wheel, wire brush, or flap wheel.  We like the Black & Decker 6-Amp Angle Grinder BDEG400 model for this job. Very reliable and long lasting.

B&D 6 Amp

A hand-held, battery-powered drill with a wire brush or wire brush cup will also work. Remember, when working with any power tools, you must wear safety glasses, at minimum a face shield and long sleeves to protect your eyes and body from wire fragments that can be thrown from the brush. Try not apply too much pressure to an angle grinder as the tool may kick back and cause severe injuries. Get very familiar with your grinder before you get too fancy.

3|Once all parts have been cleaned and you have removed all of the mill scale, it is important to complete the project in due time before the metal rusts. Also, do not forget to wear rubber gloves to protect your hands. Removing the mill scale off mild steel is crucial.  Using a  wire brush for the entire project prior to finishing is critical for assurance that the paint will stick.


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