In the designation 4130, which statement is true about the first digit?

In the designation 4130, which statement is true about the first digit?

• A. Percentage Of Carbon In The Alloy
• B. Basic Alloying Element
• C. Second Digit
• D. Total Alloy Content

Answer: (B)

In SAE/AISI steel designations, the leading digit identifies the primary alloying element category used to classify the alloy. For 4130, that first digit places the steel in the chromium-molybdenum (chromoly) family, meaning chromium is the main alloying element (with molybdenum as a significant companion). This first digit does not indicate carbon percentage, the second digit, or total alloy content. The remaining digits refine the composition within that family. So the first digit being the basic alloying element is the correct interpretation.

In SAE/AISI steel designations, the leading digit identifies the primary alloying element category used to classify the alloy. For 4130, that first digit places the steel in the chromium-molybdenum (chromoly) family, meaning chromium is the main alloying element (with molybdenum as a significant companion). This first digit does not indicate carbon percentage, the second digit, or total alloy content. The remaining digits refine the composition within that family. So the first digit being the basic alloying element is the correct interpretation.