In the SAE-AISI system, the last two digits indicate which of the following?

In the SAE-AISI system, the last two digits indicate which of the following?

• A. The chemical composition range of the steel
• B. Any SAE number that begins with a number greater than one is an alloy steel
• C. The last two digits indicate the range of carbon in hundredths of 1%
• D. The brand of steel

Answer: (C)

In the SAE-AISI numbering, the final two digits show the carbon content of the steel, expressed as hundredths of a percent. So a grade like 1010 means about 0.10% carbon, 1018 about 0.18%, and 4140 about 0.40% carbon. Those last two digits directly reflect the carbon percentage, which strongly influences properties such as strength and hardness. The digits before identify the steel family and any alloying elements, but the last two digits specifically pin down how much carbon is present. This isn’t a brand or a general chemical range, and the rule about the first digit indicating alloy content isn’t the point being tested here.

In the SAE-AISI numbering, the final two digits show the carbon content of the steel, expressed as hundredths of a percent. So a grade like 1010 means about 0.10% carbon, 1018 about 0.18%, and 4140 about 0.40% carbon. Those last two digits directly reflect the carbon percentage, which strongly influences properties such as strength and hardness. The digits before identify the steel family and any alloying elements, but the last two digits specifically pin down how much carbon is present. This isn’t a brand or a general chemical range, and the rule about the first digit indicating alloy content isn’t the point being tested here.