Image courtesy: Wikimedia Commons
How to Identify Metals
Metals are malleable and fusible materials that can be turned into various objects, from kitchen utensils to machines.
If you are planning to work in the metal industry, you wish to sell scrap metals or there’s something metal made that you need to repair, you may need to have knowledge on how to identify metals.
There are various tests that you could do to help you in this. Metals also have their own characteristics so familiarizing yourself with them would let you in their identification.
Different Metal Tests
Various tests can be made in order to determine the type of metal that you have or need.
One of them is the appearance test. Their physical features could help determine what they are. You must be familiar with how they look and you can do this by checking images of various metals on books.
However, there are metals that look similar to each other, which is why the other tests must also be done to help determine the correct type.
For instance, gold and brass are often being confused with each other because they have the same color. Gold is heavier and brass has a bell like vibrating sound if you try to hit it.
The magnet test is another one.
Metals can be ferrous and non-ferrous. Ferrous metals contain iron making them magnetic. Non-ferrous on the other hand are non-magnetic and they are also more valuable than ferrous metals.
Use a magnet for this test to determine if you have a ferrous or non-ferrous metal.
There’s also the fracture test that lets you identify a metal by analyzing its broken part.
Another common test made is the spark test. Metals have their own spark characteristics and you could check this by touching the metal to the grinder to produce spark.
Observe the sparks created and take note of the following:
- Color: The color of sparks that these metals would produce varies from each other. For instance, yellow sparks could be from a wrought iron, titanium could produce white sparks, while nickel could have dark red sparks
- Length: The spark’s length could also help you determine the type of metal. For example, tungsten carbide has light orange sparks that are usually only around 3 inches, while alloy steel has longer sparks that’s typically around 60 inches.
- Sprigs and Forks: These would tell the carbon content of the metal. More forks and sprigs mean higher carbon content.
Check out this video by TheProRancher showing how spark test is done for identifying various types of metals:
Identifying Common Types of Metals
Aluminum. This metal is grey and shiny but it doesn’t sparkle. It has a density of 2.70 g/cm3. When it comes into contact with air, it forms clear oxide. It would melt once it reaches the temperature of 1217°F or 658°
Gold. This precious metal is soft, heavy and it’s shiny yellow. It doesn’t rust, which is why it’s mostly used on jewelries.
It’s an electric conductor that means that high electricity could pass through an object made of it. Its non-ferrous and it could melt when exposed to 1,947.52°F or 1,064.18°C temperature.
Brass. It’s often confused with gold because they have the same color. However, you could differentiate them by trying to hit on the object.
If there’s vibration like that of a bell, then it’s brass and not gold. However, it’s also non-ferrous like gold, although its melting point varies depending on how much brass was used for an object, but it’s typically between 1652°F to 1724°F or 900°C to 940°C
Bronze. This metal is dark coppery but it could turn greenish after some time. Like the brass, it also has bell like vibration when hit. Bronze is a combination of tin and copper, as well as a bit of lead.
Copper. It’s light red and turns greenish with oxidation. It’s often mixed with other metals to produce another type of metal like bronze and brass. It’s non-ferrous and it has a density of 8.94 g/cm3.
Lead. This is a heavy metal that’s dull grey in color, although it becomes shiny when polished. It could melt in lower temperature like 621°F or 327°C.
Iron. Like lead, its color is also dull grey. When it rusts, the color of the rust is somewhat red. It’s magnetic and it has a density of 7.87 g/cm3. It could melt when 2786°F or 1530°C is reached.
References:
http://www.smithy.com/machining-handbook/chapter-2/page/7
http://www.instructables.com/id/Identify-Metals/?ALLSTEPS
http://midcityscrap.com/2012/10/how-to-identify-different-types-of-scrap-metal/