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Introduction
ASTM A678
/ A678M covers quenched and tempered alloy structural steel plates intended for
applications requiring high strength, excellent toughness, superior
weldability, and reliable performance under demanding service conditions. These
plates are specially heat treated to provide enhanced mechanical properties,
making them suitable for heavy structural fabrication and critical engineering
applications.
ASTM A678
alloy structural steel plates are widely used in bridge construction, heavy
machinery, mining equipment, offshore structures, construction equipment,
transportation systems, industrial machinery, and structural engineering
projects. Their combination of high tensile strength, excellent impact
resistance, and good fabrication characteristics makes them an ideal choice for
components subjected to high stresses and dynamic loading.
Due to
their outstanding mechanical performance and structural reliability, ASTM A678
plates are extensively utilized in industries requiring durable and
long-lasting structural materials capable of operating under severe
environmental and loading conditions.
Ladhani
Metal Corporation is a manufacturer, supplier, and exporter of ASTM A678 /
A678M Alloy Structural Steel Plates, supplying premium-quality quenched and
tempered alloy steel plates for structural, industrial, and engineering
applications worldwide.
Applicable Standard
Standard
Specification: ASTM A678 / A678M
Organization:
ASTM International
Title:
Standard Specification for Quenched and Tempered Carbon and High-Strength
Low-Alloy Structural Steel Plates
This
specification covers quenched and tempered carbon and high-strength low-alloy
structural steel plates intended for welded structures requiring high strength
and excellent toughness.
Forms of Supply
ASTM A678
steel products are supplied in the following forms:
• Alloy
structural steel plates
• Quenched and tempered steel plates
• High-strength structural plates
• Heavy thickness plates
• Hot rolled plates
• Cut-to-size plates
• CNC-cut plates
• Flame-cut plates
• Fabrication-ready plates
• Structural components
• Engineering plates
• Custom-sized plates
Grades Covered Under
ASTM A678 / A678M
Grade A
Grade
B
Grade C
Grade D
Supply Condition
•
Quenched and tempered
• Heat treated
• Stress relieved (when specified)
• Fabrication-ready condition
• Shot blasted (when required)
Surface Finish
• Mill
finish
• Shot blasted finish
• Ground finish
• Pickled finish
• Fabrication finish
• Machined finish (when specified)
Standard Sizes
Plates
Thickness:
6 mm to 150 mm
Width:
1000 mm to 4000 mm
Length:
Up to 12000 mm
Custom
dimensions and processed plate components are available according to customer
requirements.
Chemical Composition
of ASTM A678 / A678M
|
Element |
Grade A |
Grade B |
Grade C |
Grade D |
|
Carbon, max |
0.16 |
0.20 |
0.22 |
0.22 |
|
Manganese |
||||
|
1½ in. [40 mm]
and under in thickness |
0.90–1.50 |
0.70–1.35 |
1.00–1.60 |
1.15–1.50 |
|
Over 1½ to 2½ in.
[40 to 65 mm], incl |
B |
1.00–1.60 |
1.00–1.60 |
1.15–1.50 |
|
Over 2½ to 3 in.
[65 to 75 mm], incl |
B |
B |
B |
1.15–1.50 |
|
Phosphorus, max |
0.035 |
0.035 |
0.035 |
0.035 |
|
Sulfur, max |
0.04 |
0.04 |
0.04 |
0.04 |
|
Silicon |
0.15–0.50 |
0.15–0.50 |
0.20–0.50 |
0.15–0.50 |
|
Vanadium |
— |
— |
— |
0.04–0.11 |
|
Columbium |
— |
— |
— |
C |
|
Nitrogen |
— |
— |
— |
0.01–0.03 |
|
Copper, min, when
specified |
0.20 |
0.20 |
0.20 |
0.20 |
Notes
Note 1: Small amounts of alloying
elements may be present but shall not exceed: Cu
0.35%, Ni 0.25%, Cr 0.25%, Mo 0.08%.
Note 2: Where "—" appears in this table, there is no requirement.
A: Boron may be added only by
agreement between the producer and the purchaser.
B: This size and grade is not
described in this specification.
C: Columbium may be present
in the amount of 0.01–0.05%.
Mechanical Requirements
|
Property |
Grade
A |
Grade
B |
Grade
C |
Grade
D |
|
Yield Strength, min. ksi [MPa] |
||||
|
To ¾ in. [20 mm], incl |
50 [345] |
60 [415] |
75 [515] |
75 [515] |
|
Over ¾ to 1½ in. [20 to 40 mm], incl |
50 [345] |
60 [415] |
70 [485] |
75 [515] |
|
Over 1½ to 2 in. [40 to 50 mm], incl |
C |
60 [415] |
65 [450] |
75 [515] |
|
Over 2 to 2½ in. [50 to 65 mm], incl |
C |
60 [415] |
C |
75 [515] |
|
Over 2½ to 3 in. [65 to 75 mm], incl |
C |
C |
C |
75 [515] |
|
Tensile Strength, ksi [MPa] |
||||
|
To ¾ in. [20 mm], incl |
70–90 [485–620] |
80–100 [550–690] |
95–115 [655–790] |
90–110 [620–760] |
|
Over ¾ to 1½ in. [20 to 40 mm], incl |
70–90 [485–620] |
80–100 [550–690] |
90–110 [620–760] |
90–110 [620–760] |
|
Over 1½ to 2 in. [40 to 50 mm], incl |
C |
80–100 [550–690] |
85–105 [585–720] |
90–110 [620–760] |
|
Over 2 to 2½ in. [50 to 65 mm], incl |
C |
80–100 [550–690] |
C |
90–110 [620–760] |
|
Over 2½ to 3 in. [65 to 75 mm], incl |
C |
C |
C |
90–110 [620–760] |
|
Elongation in 2 in. [50 mm], min, % |
22 |
22 |
19 |
18 |
Notes
A.
See Specification under the Tension Tests section of Specification A6/A6M.
B.
Measured at 0.2% offset or 0.5% extension under load.
C.
This size and grade is not described in this specification.
D.
For thicknesses of ¾ in. [20 mm] and under, measured on 1½-in. [40-mm] wide
full-thickness rectangular specimens as shown in Fig. 4 of Test Methods and
Definitions A370. The elongation is measured in a 2-in. [50-mm] gage length
which includes the fracture and which shows the greatest elongation.
E. For plates wider than 24 in. [600
mm], the elongation requirement is reduced by two percentage points. See
elongation requirement adjustments in the Tension Tests section of
Specification A6/A6M.
Mechanical
properties may vary depending on plate thickness and heat treatment condition.
Key Features of ASTM
A678 / A678M Plates
• High
mechanical strength
• Excellent impact toughness
• Superior weldability
• Outstanding fatigue resistance
• Excellent structural integrity
• Good formability
• Reliable heat treatment response
• Excellent dimensional stability
• Suitable for demanding structural applications
• Long service life
Applications of ASTM
A678 / A678M Plates
Structural Engineering
• Heavy
structural frameworks
• Industrial buildings
• Load-bearing structures
• Engineering projects
Bridge Construction
• Bridge
girders
• Structural supports
• Bridge components
• Infrastructure projects
Mining Industry
• Mining
equipment
• Crusher structures
• Heavy machinery components
• Material handling equipment
Construction Equipment
•
Excavators
• Cranes
• Earthmoving equipment
• Structural machine frames
Transportation Industry
• Heavy
vehicle structures
• Railway equipment
• Trailer chassis
• Specialized transport equipment
Industrial Manufacturing
• Heavy
engineering equipment
• Machine frames
• Industrial structures
• Fabricated steel components
Fabrication and
Welding
ASTM A678
alloy structural steel plates provide excellent fabrication performance when
proper welding procedures are followed.
•
Suitable for conventional welding processes
• Good bending and forming characteristics
• Excellent machining performance
• Suitable for heavy fabrication work
• Reliable performance in welded structures
• Excellent dimensional accuracy
Appropriate
welding procedures and consumables should be selected based on the plate
thickness and service requirements.
Heat Treatment
ASTM A678
plates are supplied in the quenched and tempered condition to achieve the
required mechanical properties.
•
Quenching increases strength and hardness
• Tempering improves toughness and ductility
• Controlled heat treatment ensures uniform mechanical properties
• Stress relieving may be performed after fabrication
• Proper thermal processing enhances service reliability
Advantages of ASTM
A678 / A678M Plates
•
Exceptional structural strength
• Excellent impact resistance
• Superior toughness
• High fatigue resistance
• Excellent fabrication characteristics
• Reliable long-term performance
• Suitable for heavy-duty structural applications
• Consistent mechanical properties
• Reduced maintenance requirements
• Cost-effective engineering solution
Conclusion
ASTM A678
/ A678M Alloy Structural Steel Plates are high-strength quenched and tempered
steel plates developed for structural applications requiring outstanding
mechanical performance, toughness, and reliability. Their superior strength,
weldability, and impact resistance make them suitable for bridges, mining
equipment, construction machinery, transportation systems, and heavy
engineering structures operating under demanding service conditions.
Ladhani Metal Corporation
supplies ASTM A678 / A678M alloy structural steel plates in various grades,
thicknesses, and customized dimensions, delivering dependable material
solutions for structural, industrial, and engineering projects worldwide.
FOR REQUIREMENT OF THIS GRADE
OR FOR DETAIL CONTACT US AT :-
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