Residual flux density of carbon steel – truth check Evaluate the statement: “Carbon steel has a residual flux density (remanence) of exactly 1 Wb/m^2.” Decide whether it is true or false for general carbon steels used in magnetic applications.

Introduction / Context:
Residual flux density (remanent flux density, Br) is a key parameter of ferromagnetic materials measured from their hysteresis loops. It is material- and processing-dependent, not a single fixed number for all samples labeled “carbon steel.”

Given Data / Assumptions:

• We refer to general carbon steels, not a specific grade with prescribed heat treatment.
• Br depends on composition, grain structure, processing, and measurement conditions.

Concept / Approach:

Carbon steels commonly show remanence values on the order of 1–1.5 T (Wb/m^2), but exact figures vary widely. Since the statement claims a definitive value of exactly 1 Wb/m^2, it is not generally correct. Engineering datasheets quote ranges and typical values; one must consult the specific alloy and temper.

Step-by-Step Solution:

Verification / Alternative check:

Hysteresis loops for low-carbon steels and electrical steels report Br values depending on silicon content, lamination thickness, stress relief, and rolling direction, confirming variability.

Why Other Options Are Wrong:

Options suggesting stainless steels or transformer steels do not address the generality problem; “true only at cryogenic temperatures” is irrelevant to the variability across grades.

Common Pitfalls:

Assuming a single nominal “textbook number” applies to all carbon steels without considering grade and processing.

Final Answer:

False