ASTM A193 Standard Specification for Alloy-Steel and Stainless Steel Bolting Materials for High-Temperature Service Grade: B7  — Ferritic Steels / Chromium-Molybdenum Chemical Requirements (Composition, percent) C: 0.38-0.48 Mn: 0.75-1.00 P: ≤0.035 S: ≤0.040 Si: 0.15-0.35 Cr: 0.80-1.10 Mo: 0.15-0.25 *For bar sizes over 3-1/2 in. [90 mm], inclusive, the carbon content may be 0.50 %, max.…