SA 387 Grade 11 Class 1

SA387 Grade 11 Class 1 is a chromium-molybdenum alloy steel plate, typically used for welded boilers and pressure vessels designed for elevated temperature service. It's one of two classes (Class 1 and Class 2) within the SA387 Grade 11 standard, differing in their tensile properties.

Chat Now

Send Inquiry

Product Description

1.What is the chemical composition of SA 387 Grade 11 Class 1?

Element	Composition Range (wt%)	Key Role
Carbon (C)	0.05–0.17%	Controls strength & weldability
Manganese (Mn)	0.40–0.70%	Enhances strength & hardenability
Phosphorus (P)	≤0.025%	Impurity (reduces toughness if high)
Sulfur (S)	≤0.025%	Impurity (causes hot cracking)
Silicon (Si)	0.15–0.50%	Deoxidizer, improves strength
Chromium (Cr)	1.00–1.50%	High-temperature oxidation resistance
Molybdenum (Mo)	0.45–0.65%	Creep resistance at elevated temps
Others	Cu ≤0.30%, Ni ≤0.25%	Residual elements (controlled)

2.What is the equivalent material of ASTM SA 387 Grade 11 Class 1?

Standard	Equivalent Designation	Notes
EN (Europe)	13CrMo4-5 (EN 10028-2)	Nearly identical composition
JIS (Japan)	SCMV 4	Similar Cr-Mo content
GB (China)	15CrMoR (GB 713)	Used for pressure vessels in China
ISO	P11 (ISO 9328-2)	International designation
DIN (Germany)	15CrMo5	Older DIN standard

3.What are the core differences between SA 387 Gr.11 Class 1 and Class 2?

Item	SA 387 Gr.11 Class 1	SA 387 Gr.11 Class 2
Heat Treatment	Annealed/Normalized + Tempered	Quenched & Tempered (Q&T)
Yield Strength	≥205 MPa (30 ksi)	≥310 MPa (45 ksi)
Tensile Strength	415–585 MPa (60–85 ksi)	515–690 MPa (75–100 ksi)
Elongation	≥22% (in 50mm gauge length)	≥20% (in 50mm gauge length)
Charpy Impact	Generally not required	≥27J @ -30°C (mandatory if thickness ≥20mm)
Microstructure	Ferrite + Pearlite	Tempered Bainite/Martensite
Weldability	Better (lower preheat ~150°C)	Requires strict PWHT (595–675°C)
Typical Applications	Low/medium-pressure vessels, storage tanks	High-pressure reactors, power plant piping