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ASTM A387/A387M Grade 9 vs ASTM A387/A387M Grade 21

Related Material — 69.9% match based on chemical composition and mechanical property overlap.

ASTM A387/A387M Grade 9 (ASTM A387/A387M:2011) and ASTM A387/A387M Grade 21 (ASTM A387/A387M:2011) are both steel grades. Both fall under the Alloy Steel category. ASTM A387/A387M Grade 9 is typically used for welded boilers and pressure vessels for elevated temperature service, while ASTM A387/A387M Grade 21 is commonly used for welded boilers and pressure vessels for elevated temperature service. ASTM A387/A387M Grade 9 is defined under ASTM International, originating from United States, while ASTM A387/A387M Grade 21 is defined under ASTM International, originating from United States.

As per chemical composition, ASTM A387/A387M Grade 9 vs ASTM A387/A387M Grade 21 is a 84.6% match. As per mechanical properties, the match is 100%. Combined, this makes them a related material overall at 69.9%.

Frequently Compared With ASTM A387/A387M Grade 9:
IS 1570 (Part 7) 10Cr36Mo10H IS 4367 07Cr4Mo6 IS 1570 (Part 4) 07Cr4Mo6 NF A35-565 100C6 IS 1570 (Part 4) 105Cr5 IS 1570 (Part 4) 10Mo6 IS 1570 (Part 7) 10Mo6H UNI 11234 100Cr6 IS 1570 (Part 4) 103Cr4 IS 1570 (Part 4) 103Cr6 IS 1570 (Part 4) 10Cr20Mo6 IS 4367 10Cr9Mo10
Match Breakdown
CHEMISTRY MATCH
84.6%
MECHANICAL MATCH
100%
OVERALL
69.9%
Specifications
Property ASTM A387/A387M Grade 9 ASTM A387/A387M Grade 21
Standard ASTM A387/A387M:2011 ASTM A387/A387M:2011
Category Alloy Steel Alloy Steel
C (%) <=0.15 0.05-0.15
Mn (%) 0.30-0.60 0.30-0.60
P (%) <=0.025 <=0.025
S (%) <=0.025 <=0.025
Si (%) <=1.00 <=0.50
Cr (%) 8.00-10.00 2.75-3.25
Mo (%) 0.90-1.10 0.90-1.10
V (%) <=0.04 Not specified
Matched by chemical composition and mechanical properties, not a formal equivalence claim. Always verify against the applicable standard before substitution.
Mechanical Properties
Property ASTM A387/A387M Grade 9 ASTM A387/A387M Grade 21
Tensile Strength 415-585 MPa 415-585 MPa
Yield Strength >=205 MPa >=205 MPa
Elongation >=18% >=18%
Condition Class 1 plates, no thickness ranges printed; elongation in 50 mm gauge length Class 1 plates, no thickness ranges printed; elongation in 50 mm gauge length
Typical Applications
ASTM A387/A387M Grade 9
Welded boilers and pressure vessels for elevated temperature service
ASTM A387/A387M Grade 21
Welded boilers and pressure vessels for elevated temperature service
Key Differences
Can ASTM A387/A387M Grade 9 Be Substituted With ASTM A387/A387M Grade 21?
ASTM A387/A387M Grade 9 and ASTM A387/A387M Grade 21 share some compositional similarity but differ enough that substitution should not be assumed. Review the differences above carefully, and consult the applicable standard or a metallurgist before using one in place of the other.
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ASTM A387/A387M Grade 9
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ASTM A387/A387M Grade 21
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Frequently Asked Questions
What is the difference between ASTM A387/A387M Grade 9 and ASTM A387/A387M Grade 21?
ASTM A387/A387M Grade 9 specifies V which is not specified for ASTM A387/A387M Grade 21.
Can ASTM A387/A387M Grade 9 be substituted with ASTM A387/A387M Grade 21?
ASTM A387/A387M Grade 9 and ASTM A387/A387M Grade 21 share some compositional similarity but differ enough that substitution should not be assumed. Review the differences above carefully, and consult the applicable standard or a metallurgist before using one in place of the other.