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GB/T 1591 Q690MD vs GB/T 1591 Q550MD

Related Material — 68% match based on chemical composition and mechanical property overlap.

GB/T 1591 Q690MD (GB/T 1591:2018) and GB/T 1591 Q550MD (GB/T 1591:2018) are both steel grades. Both fall under the Structural Steel category. GB/T 1591 Q690MD is typically used for general structure for engineering (plates, strips, bars and sections), while GB/T 1591 Q550MD is commonly used for general structure for engineering (plates, strips, bars and sections). GB/T 1591 Q690MD is defined under Guobiao Standards (GB/T), originating from China, while GB/T 1591 Q550MD is defined under Guobiao Standards (GB/T), originating from China.

As per chemical composition, GB/T 1591 Q690MD vs GB/T 1591 Q550MD is a 98.3% match. As per mechanical properties, the match is 7.4%. Combined, this makes them a related material overall at 68%.

Frequently Compared With GB/T 1591 Q690MD:
AS/NZS 3679.1 300 CSA G40.21 300W AS/NZS 3679.1 350 CSA G40.21 400W ASTM A283C ASTM A572 Gr.65
Other Structural Steel Grades to Compare With GB/T 1591 Q690MD:
GOST 19281 09G2S CSA G40.21 260W CSA G40.21 350W CSA G40.21 400A CSA G40.21 480W ASTM A1008 SS Grade 50
Match Breakdown
CHEMISTRY MATCH
98.3%
MECHANICAL MATCH
7.4%
OVERALL
68%
Specifications
Property GB/T 1591 Q690MD GB/T 1591 Q550MD
Standard GB/T 1591:2018 GB/T 1591:2018
Category Structural Steel Structural Steel
C (%) <=0.18 <=0.18
Si (%) <=0.60 <=0.60
Mn (%) <=2.00 <=2.00
P (%) <=0.030 <=0.030
S (%) <=0.025 <=0.025
Nb (%) 0.01-0.11 0.01-0.11
V (%) 0.01-0.12 0.01-0.12
Ti (%) 0.006-0.05 0.006-0.05
Cr (%) <=1.00 <=0.80
Ni (%) <=0.80 <=0.80
Cu (%) <=0.80 <=0.80
Mo (%) <=0.30 <=0.30
N (%) <=0.025 <=0.025
B (%) <=0.004 <=0.004
Al (%) >=0.015 >=0.015
Matched by chemical composition and mechanical properties, not a formal equivalence claim. Always verify against the applicable standard before substitution.
Mechanical Properties
Property GB/T 1591 Q690MD GB/T 1591 Q550MD
Tensile Strength 770-940 MPa 670-830 MPa
Yield Strength >=690 MPa >=550 MPa
Elongation >=14% >=16%
Condition Thermomechanical processed (TMCP), nominal thickness or diameter up to 16 mm (tensile strength: up to 40 mm) Thermomechanical processed (TMCP), nominal thickness or diameter up to 16 mm (tensile strength: up to 40 mm)
Typical Applications
GB/T 1591 Q690MD
General structure for engineering (plates, strips, bars and sections)
GB/T 1591 Q550MD
General structure for engineering (plates, strips, bars and sections)
Can GB/T 1591 Q690MD Be Substituted With GB/T 1591 Q550MD?
GB/T 1591 Q690MD and GB/T 1591 Q550MD 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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GB/T 1591 Q690MD
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GB/T 1591 Q550MD
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Frequently Asked Questions
What is the difference between GB/T 1591 Q690MD and GB/T 1591 Q550MD?
Both grades share a similar composition profile; see the specification table above for the exact chemistry and mechanical property values.
Can GB/T 1591 Q690MD be substituted with GB/T 1591 Q550MD?
GB/T 1591 Q690MD and GB/T 1591 Q550MD 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.