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Knowing Steel Grades

Though builders know that there are different grades of steel used for different purposes, laypersons might not. Here are some different grades of steel according to SAE International.

What Is Steel?

Steel is a metal made from an alloy of carbon and iron. Carbon needs to be added to iron to make steel because iron is too soft without it. The amount of carbon is between .002 percent and 2.1 percent. If it’s higher than that, the steel becomes brittle and hard to work with.

However, carbon isn’t the only alloy in steel. Other alloys include nickel, titanium, chromium and molybdenum. These give the steel different qualities.

The Different Grades

Steel is graded in a surprisingly complex system, but here are the basics:

Carbon Steel and Alloy Steel

The grade of steel is expressed by a four digit number. The first number tells the buyer or the builder what the chief alloy was.

If the chief alloy was carbon, the number is 1. Nickel steel is 2, Nickel chromium steel is 3, Molybdenum steel is 4, chromium steel is 5, chromium vanadium steel is 6, tungsten steel is 7, nickel chromium molybdenum steel is 8, and silicon manganese steel is 9.

The second number in the grade designates the secondary alloys.

The last two numbers let the builder know how much carbon is in the steel. For example, if carbon steel is being used, 10 followed by two more digits means that the steel is alloyed both primarily and secondarily with carbon. Sometimes an H is added to let the builder or buyer know that the steel needs a certain hardness value.

Stainless Steel

Stainless steel is steel with at least 10.5 percent chromium. This gives the steel a shine and helps it resist corrosion and rust. Stainless steel is designated by a series. The series range from type 102 to type 665, which are super alloys.

What Different Steel Grades Are Used For

When it comes to stainless steel, Type 102 and 202 steel are considered all purpose steels. Type 102 can be used for furniture making. Type 301 is known for being able to be stretched into wire and is easy to weld. Type 304 is the most common type of stainless steel and has a ratio of 18 percent chromium and eight percent nickel.

The second most common type of stainless steel type is 316, which is used for surgical instruments and in boat building because it resists corrosion. It’s also sought after for use in nuclear plants. The grade 316T has an alloy of titanium, which makes it especially heat resistant.

Other Steels

Low carbon steel is also called mild steel and is very easy to shape and stretch. It’s also inexpensive, and so is used when a lot of steel is called for as in the framework of buildings.

Steel with a medium carbon content is durable and is used for making cars.

The very strong high carbon steel is used for springs and wires. Steel with a great deal of carbon is very hard and is used for car axles or weaponry.

A contractor who wishes to get the best grade steel for his or her project should go to a steel manufacturer for more advice.

Jason Kane is a professional blogger for Federal Steel Supply, Inc., the preferred steel and steel pipe supplier of the global community since 1979.