Metal Identification

In maintenance welding, it is very important to accurately identify base metals in order to minimize downtime and have confidence of a strong, high quality weld every time.

For example, the carbon content of steel must be determined as those containing over 0.25% carbon will require special considerations when welding. The higher the carbon content, the higher the probability is that the weld will be sensitive to hot-cracking and hardening, resulting in poor ductility. This is why it is so important to use high quality welding rods.

File Test

Chipping Test

Color Test

File Test

The fastest & easiest method of testing the carbon content of an unknown type steel without the use of chemicals or special equipment is by using any workshop file.

Steel Type	Carbon Content	File Reaction
Mild	less than 0.15%	Bites metal easily
Medium Carbon	0.15% to 0.25%	Bites with pressure
High Alloy	0.26 to 0.35 %	Bites only with force
Tool	0.36 to 0.45%	Bites with difficulty
Hardened Tool	Over 0.45%	Slides over metal

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Chipping Test

Another method of finding an unknown metal's composition is to use a chisel to remove a small piece of the metal.

Grey Cast Iron

Chips are smooth and brittle

Cast Steel

Easily chipped, can be continuous if desired

Aluminum

Chips are continuous but leave a saw edge

White Cast Iron

Metal is brittle and breaks into small fragments

Malleable Iron

Rough chips

High Carbon Steel

Lighter color at edges than mild steel, chips can be continuous

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Color Test

Some metals can be easily identified by color

Copper

Reddish Brown

Manganese Steel

Bluish in service; copper-color in storage

Zinc, Magnesium, Aluminum, Tin & Lead

Whitish

Brass

Yellow if high zinc content, otherwise reddish

White Cast Iron

White and silvery

Grey Cast Iron

In a fractured state, grey
Will deposit grey graphite streak on contact

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