Which of the following statements pertaining to steel are true or false?
ST1: Mild steel has higher ultimate tensile strength when compared to High Carbon Steel.
ST2: TOR steel is high strength deformed bars with high yield and bond strength.
🔬 Detailed Analysis of the Statements
Let's break down each statement to determine its validity.
Analysis of Statement 1 (ST1)
"Mild steel has higher ultimate tensile strength when compared to High Carbon Steel."
This statement is about the relationship between carbon content and strength. As established, carbon is the primary hardening agent in steel.
• Mild Steel has a low carbon content (typically 0.05% to 0.25%).
• High Carbon Steel has a high carbon content (typically 0.6% to 1.0%).
Because strength increases directly with carbon content, High Carbon Steel has a significantly higher ultimate tensile strength than Mild Steel. Therefore, the statement is FALSE.
Analysis of Statement 2 (ST2)
"TOR steel is high strength deformed bars with high yield and bond strength."
This statement describes the properties of a specific type of reinforcing bar.
• TOR Steel: The name "TOR" comes from the brand name of the Toristeg Steel Corporation of Luxembourg. The process involves hot-rolling a steel bar and then cold-twisting it.
• High Strength Deformed Bars (HSD): The ribs or deformations on the surface are designed to create a strong mechanical bond with concrete. The cold-twisting process (a form of work hardening) significantly increases the steel's yield strength. The twisted, ribbed profile also provides an excellent grip within the concrete, leading to high bond strength.
Therefore, the statement is TRUE.
✅ Conclusion and Study Tips
Based on the analysis, Statement 1 is false and Statement 2 is true, making option (b) the correct choice.
💡 Study Tips for Steel Properties
- Carbon is Strength: The most fundamental rule for plain carbon steels is: More Carbon = More Strength & Hardness, but Less Ductility & Toughness.
- Deformed means Grip: The term "deformed bars" (whether TOR steel or modern TMT bars) refers to the ribs on the surface. These ribs are essential for creating a strong bond with concrete.
- Twisting/Treating means Strength: Processes like cold-twisting (TOR) or thermo-mechanical treatment (TMT) are used to increase the yield strength of the steel beyond that of plain mild steel bars.