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ASTM A387/A387M:2011 Grade 21 Steel: Specifications & Listings

ASTM A387/A387M:2011 Grade 21: Grade 21: 3Cr-1Mo chromium-molybdenum alloy steel plate for welded boilers and pressure vessels at elevated temperature. Specified in ASTM A387/A387M:2011.

Category: Alloy Steel
Grade Details
GradeASTM A387/A387M:2011 Grade 21
Standard ASTM A387/A387M:2011
ApplicationsWelded boilers and pressure vessels for elevated temperature service
Equivalent / Similar Grades
Grade Standard Region Live on M-EX
ASTM A387/A387M Grade 22 ASTM A387/A387M:2011 USA (ASTM) No activity yet
ASTM A387/A387M Grade 22L ASTM A387/A387M:2011 USA (ASTM) No activity yet
ASTM A387/A387M Grade 21L ASTM A387/A387M:2011 USA (ASTM) No activity yet
Grade ComparisonCompare With a Specific Grade →
Grade Standard Match
ASTM A387/A387M Grade 21L ASTM A387/A387M:2011 Strong Match
ASTM A387/A387M Grade 22 ASTM A387/A387M:2011 Strong Match
ASTM A387/A387M Grade 22L ASTM A387/A387M:2011 Strong Match
ASTM A387/A387M Grade 5 ASTM A387/A387M:2011 Close Alternative
IS 11169 (Part 1) 25Cr13Mo6 IS 11169 (Part 1):1984 Close Alternative
BS 970 (Part 1) 720M32 BS 970 (Part 1):1991 Related Material
BS 970 (Part 1) 897M39 BS 970 (Part 1):1991 Related Material
BS 970 (Part 1) 720M32 BS 970 (Part 1):1983 Related Material
Matched by chemical composition and mechanical properties, not a formal equivalence claim. Always verify against the applicable standard before substitution.
Chemical Composition (%)
C Mn P S Si Cr Mo
0.05-0.15 0.30-0.60 <=0.025 <=0.025 <=0.50 2.75-3.25 0.90-1.10
Mechanical Properties
Tensile Strength 415-585 MPa
Yield Strength >=205 MPa
Elongation >=18%
Condition Class 1 plates, no thickness ranges printed; elongation in 50 mm gauge length

More data from ASTM A387/A387M:2011

From the standard
Tensile properties by class 2 classes
ClassTensile strength (MPa)Yield strength, min (MPa)Elongation in 50 mm, min (%)Elongation in 200 mm, min (%)
Class 1415 to 58520518-
Class 2515 to 69031018-
Values as printed; elongation adjustments per A20/A20M. Reduction of area min 45 percent (round specimen) or 40 percent (flat specimen). Class 2 not applicable to annealed material.
Source: ASTM A387/A387M:2011, Tables 2 and 3
Heat treatment heat treatment
Minimum tempering temperature
675 deg C (1250 deg F)
Plates annealed, or normalized and tempered, or accelerated cooled and tempered where permitted by the purchaser.
Source: ASTM A387/A387M:2011, Section 5

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