ASTM A36 vs A572 Grade 50 Steel: Properties, Strength and Selection Guide
materials used in buildings, bridges, machinery, industrial equipment and
general fabrication. Although both grades can be supplied as structural steel
plate, they are not identical materials and should not be treated as automatic
substitutes.The principal difference is strength. ASTM A36 is a conventional carbon
structural steel, while ASTM A572 Grade 50 is a high-strength low-alloy,
or HSLA, structural steel. A572 Grade 50 generally provides a higher minimum
yield strength, which may allow engineers to reduce material weight in a
properly designed structure.
readily fabricated general-purpose structural steel is required. Consider
ASTM A572 Grade 50 when higher yield strength, improved strength-to-weight
performance or reduced section weight is important. The final material must
always comply with the project specification, design code, thickness range,
welding procedure and required inspection documentation.
What Is ASTM A36 Steel?
ASTM A36 is a carbon structural steel specification covering structural
shapes, plates and bars intended for riveted, bolted or welded construction
and other general structural purposes.
It is frequently selected because it combines practical strength, ductility,
formability, machinability, weldability and broad commercial availability.
Common uses include structural frames, base plates, brackets, support members,
platforms, agricultural equipment and general fabricated components.
For many commonly ordered plate thicknesses, A36 is associated with a minimum
yield strength of approximately 36 ksi, or 250 MPa. However, applicable
requirements can depend on product form and thickness. Buyers should therefore
verify the ordered specification, dimensions and mill test certificate rather
than relying only on a generic online property table.
JUDE STEEL supplies
ASTM A36 carbon steel plate
in a range of dimensions and processing conditions for international
industrial projects.
What Is ASTM A572 Grade 50 Steel?
ASTM A572 is a specification for high-strength low-alloy structural steel.
It includes several strength grades, of which Grade 50 is one of the most
commonly requested.
A572 Grade 50 achieves higher specified strength through controlled chemical
composition and alloying practices. Depending on the applicable specification
requirements, elements such as columbium, also known as niobium, vanadium or
combinations of microalloying elements may be used to develop the required
mechanical properties.
For common thickness ranges, Grade 50 is generally associated with a minimum
yield strength of 50 ksi, or 345 MPa. Strength requirements may change at
greater thicknesses, so the purchaser must confirm the exact thickness,
standard edition and mechanical property requirements before placing an order.
Compared with A36, the higher yield strength of A572 Grade 50 may permit a
lighter structural solution. However, reducing thickness or member size is an
engineering decision. Stiffness, deflection, local buckling, fatigue,
connection design, fire resistance and corrosion allowance may still control
the final dimensions.
View JUDE STEEL’s
ASTM A572 steel plate
product information for available supply and customization options.
ASTM A36 vs A572 Grade 50: Key Differences
| Comparison Item | ASTM A36 | ASTM A572 Grade 50 |
|---|---|---|
| Steel category | Carbon structural steel | High-strength low-alloy structural steel |
| Typical minimum yield strength | Approximately 36 ksi or 250 MPa for many common product forms and thicknesses |
Approximately 50 ksi or 345 MPa for common thickness ranges |
| Tensile strength | Commonly specified within an approximate range of 58–80 ksi or 400–550 MPa |
Commonly specified with a minimum near 65 ksi or 450 MPa, subject to product and thickness requirements |
| Strength-to-weight potential | Suitable for general structural design | Higher strength may support lower structural weight when permitted by engineering design |
| Welding | Generally weldable with an approved procedure suited to thickness, restraint and service conditions |
Generally weldable, but low-hydrogen procedures and tighter welding controls are commonly required |
| Forming | Generally suitable for routine forming and fabrication | Formable, although higher strength can increase forming force and springback |
| Material price | Often lower on a price-per-ton basis | May carry a higher material price but can reduce total steel weight in suitable designs |
| Typical purchasing priority | Economy, availability and general fabrication | Higher strength and structural efficiency |
The table provides a practical overview rather than a substitute for the
governing ASTM standard, engineering drawings or project specification.
Mechanical requirements must be checked against the ordered product form,
thickness and applicable standard edition.
Mechanical Property Comparison
Yield strength
Yield strength indicates the stress level at which permanent deformation
begins. It is one of the most important values in structural design.
A572 Grade 50 has a nominal minimum yield strength about 39% higher than the
commonly referenced 36 ksi minimum of A36:
50 ksi ÷ 36 ksi ≈ 1.39
This difference does not mean that an A572 Grade 50 plate can automatically
be made 39% thinner. Structural components must also satisfy requirements for
stiffness, deflection, buckling, fatigue, impact loading, connections and
corrosion allowance.
Tensile strength
Tensile strength describes the maximum tensile stress the material can resist
before fracture during a tensile test. A572 Grade 50 generally has a higher
specified minimum tensile strength than A36.
Both yield and tensile values should appear on the material test report. For
safety-critical projects, purchasers should confirm that the reported results
correspond to the correct heat number, plate thickness and delivery condition.
Elongation and ductility
Structural steel must provide adequate ductility so that it can deform before
fracture. A36 is often valued for its balanced ductility and fabrication
behavior. A572 Grade 50 also provides specified elongation, but elongation
requirements can vary according to specimen geometry, thickness and product
form.
When significant cold bending, rolling or severe forming is required, the
purchaser should specify the bend radius, forming direction and temperature
before production.
Chemical Composition: Why the Grades Perform Differently
A36 is classified as carbon structural steel. Its specification controls
elements such as carbon, manganese, phosphorus, sulfur, silicon and copper,
depending on the product form and purchasing requirements.
A572 Grade 50 is an HSLA steel. Its higher strength is developed through
controlled composition and microalloying rather than simply adding a high
carbon content. This approach can provide higher yield strength while
maintaining practical weldability and fabrication performance.
Chemical limits are affected by thickness, product form and production route.
Consequently, a single universal chemistry table should not be used for every
A36 or A572 Grade 50 order.
For welded fabrication, purchasers may also request the actual carbon
equivalent or the chemical values needed to calculate it. Carbon equivalent,
plate thickness, heat input, restraint and ambient temperature help the
welding engineer determine whether preheating or other controls are required.
Weldability and Fabrication
Both A36 and A572 Grade 50 can be used in welded construction when a suitable
welding procedure is developed and followed. Welding decisions should be based
on the applicable fabrication code, filler metal classification, joint design,
plate thickness, carbon equivalent, restraint and service environment.
Welding ASTM A36
A36 is widely regarded as a practical fabrication grade. Thin and moderately
thick A36 components are commonly welded using standard structural welding
processes. Nevertheless, critical structures still require approved welding
procedure specifications, qualified welders and appropriate inspection.
Welding ASTM A572 Grade 50
A572 Grade 50 is also readily weldable when correct procedures are used.
Because it is a higher-strength material, low-hydrogen welding consumables
and controlled low-hydrogen practices are commonly required under applicable
structural welding rules.
The welding procedure may need to address:
- Base-metal specification and thickness
- Filler-metal strength and hydrogen classification
- Minimum preheat and interpass temperature
- Maximum heat input where applicable
- Joint restraint and welding sequence
- Required nondestructive examination
- Service temperature and toughness requirements
from a generic blog article. The welding procedure must comply with the
governing code and be approved for the specific material thickness, joint
configuration and service conditions.
Cutting, drilling and machining
Both grades can be processed by plasma cutting, laser cutting, oxy-fuel
cutting, drilling, milling and other conventional methods. A572 Grade 50’s
higher strength may require greater cutting or forming force and can affect
tool wear, springback and process settings.
For thick plates or components with tight dimensional tolerances, cutting
sequence, heat input, residual stress and final machining allowance should be
considered before production begins.
Typical Applications
Common ASTM A36 applications
- General building structures
- Base plates and connection plates
- Frames, brackets and support structures
- Platforms, walkways and industrial floors
- Agricultural and construction equipment
- General machinery components
- Fabricated tanks and non-pressure structural parts
Common ASTM A572 Grade 50 applications
- Heavy structural frames
- Bridge components when permitted by the project specification
- Transmission towers and utility structures
- Crane structures and material-handling equipment
- Heavy machinery and equipment frames
- Mining, energy and infrastructure projects
- Weight-sensitive structural components
Neither grade provides the same atmospheric corrosion resistance as a
dedicated weathering steel grade. When carbon steel will be exposed to water,
salt, chemicals or humid outdoor conditions, the design should include a
suitable coating system, corrosion allowance or another appropriately
specified material.
How to Choose Between A36 and A572 Grade 50
the design requires conventional structural strength, the component is not
strongly weight-sensitive, easy sourcing is important and the project
specification explicitly permits ASTM A36.
the design benefits from higher yield strength, reduced structural weight is
valuable, heavy-duty performance is required and the fabrication team can
apply the specified welding and inspection procedures.
1. Review the engineering drawings
The material grade shown on approved drawings must take priority over general
commercial preferences. A supplier should not replace A36 with A572 Grade 50,
or A572 Grade 50 with A36, without written engineering approval.
2. Check whether strength or stiffness controls the design
Higher-strength steel can improve load resistance, but it has approximately
the same elastic modulus as ordinary structural carbon steel. Therefore,
changing from A36 to A572 Grade 50 does not automatically improve elastic
stiffness.
When deflection or vibration controls the design, the required section size
may remain similar even after a higher-strength grade is selected.
3. Consider total fabricated cost
Material price per ton is only one part of the decision. Total project cost
may include:
- Required steel weight
- Plate nesting and cutting yield
- Welding labor and consumables
- Machining and forming time
- Inspection and testing
- Surface treatment
- Packaging and international freight
A572 Grade 50 may be more expensive per ton but more economical in a design
that safely reduces total steel weight. In another project, readily available
A36 may provide the lowest completed fabrication cost.
4. Confirm impact-toughness requirements
Standard mechanical properties do not automatically guarantee suitability
for low-temperature or dynamic service. If the structure will operate in a
cold climate, experience impact loading or contain fracture-critical details,
the purchaser should state the required Charpy V-notch test temperature,
absorbed energy and sampling requirements.
5. Evaluate corrosion protection
Both grades generally require protective treatment in corrosive environments.
Options may include shop primer, industrial paint, metallizing or other
project-approved coating systems.
For projects requiring zinc-coated products rather than uncoated structural
plate, review JUDE STEEL’s
galvanized steel products
.
Can A572 Grade 50 Replace A36?
A572 Grade 50 has higher specified yield strength, but it should not be
substituted for A36 solely because it appears stronger. Material substitution
can affect connection design, welding procedure, bend radius, toughness,
procurement documentation and code compliance.
A substitution should be reviewed by the responsible engineer and documented
in writing. The review should confirm:
- The governing design code permits the alternative grade
- The product form and thickness are covered by the specification
- Yield, tensile and elongation requirements are acceptable
- Chemical composition and weldability are suitable
- Required toughness testing is included
- Connections and bolts remain compatible with the design
- The fabrication procedure is qualified for the replacement material
Replacing A572 Grade 50 with A36 is usually more restrictive because the lower
yield strength of A36 may reduce the component’s design capacity.
Purchasing and Inspection Checklist
An accurate request for quotation helps prevent technical disputes, production
delays and unexpected costs. A professional RFQ should include the following
information.
| RFQ Item | Information to Specify |
|---|---|
| Material | ASTM A36/A36M or ASTM A572/A572M Grade 50, including the project-required standard edition |
| Product form | Plate, sheet, bar, profile or fabricated component |
| Dimensions | Thickness, width, length and dimensional tolerances |
| Quantity | Total weight, number of plates or cut-piece quantity |
| Delivery condition | As rolled, normalized or another condition required by the specification |
| Testing | Tensile test, impact test, ultrasonic test or other project inspection |
| Certification | Mill test certificate type and any third-party inspection requirement |
| Processing | Cutting, drilling, beveling, bending, welding or machining |
| Surface | Mill finish, shot blasting, shop primer or specified coating |
| Marking | Grade, heat number, plate number and project identification |
| Packaging | Export seaworthy packing and any lifting or bundle restrictions |
Documents to verify before shipment
- Material test certificate with matching heat numbers
- Chemical composition results
- Yield strength, tensile strength and elongation results
- Impact-test results when specified
- Dimensional inspection records
- Ultrasonic or other nondestructive examination reports when required
- Surface and marking photographs
- Packing list and shipping documentation
JUDE STEEL applies controlled inspection and documentation procedures for
export steel orders. Learn more about our
quality control process
.
Frequently Asked Questions
Is A572 Grade 50 stronger than A36?
Yes. For common thickness ranges, A572 Grade 50 is generally specified
with a minimum yield strength of approximately 50 ksi or 345 MPa, compared
with approximately 36 ksi or 250 MPa for commonly supplied A36 products.
Exact requirements must be checked by thickness and product form.
Can A572 Grade 50 be used instead of A36?
It may be technically possible in some projects, but substitution requires
approval from the responsible engineer. Welding, toughness, product form,
thickness, connection design and documentation must all be reviewed.
Which steel grade is easier to weld?
Both grades are weldable with suitable procedures. A36 is often simpler
for routine fabrication, while A572 Grade 50 commonly requires
low-hydrogen welding practices and closer control of filler metal,
preheat and heat input.
Does A572 Grade 50 weigh less than A36?
The two steels have essentially similar density. A572 Grade 50 does not
weigh less at the same dimensions. It may reduce total structural weight
only when an engineer uses its higher strength to design a smaller or
thinner component.
Is A572 Grade 50 more corrosion-resistant than A36?
A572 Grade 50 should not be assumed to provide weathering-steel corrosion
resistance. Both materials normally require appropriate surface protection
in corrosive environments unless the project specifies another suitable
grade or coating system.
Which grade is better for bridges?
The answer depends on the bridge specification and governing design code.
Higher-strength structural steel is often useful in bridge construction,
but bridge projects may require a dedicated bridge specification,
toughness testing or atmospheric-corrosion resistance rather than a
generic A36 or A572 Grade 50 order.
Is A36 cheaper than A572 Grade 50?
A36 is often less expensive per ton, but final prices depend on thickness,
dimensions, quantity, origin, testing, processing and market conditions.
A572 Grade 50 may reduce total project cost when its higher strength allows
a lower steel weight.
What certificate should be requested with structural steel plate?
Buyers should request a traceable mill test certificate showing the heat
number, chemical composition and mechanical test results. Impact testing,
ultrasonic inspection and third-party inspection should be stated in the
purchase order when required.
Conclusion
ASTM A36 and ASTM A572 Grade 50 are both important structural steels, but they
serve different design priorities. A36 offers economical and practical
performance for general structural fabrication. A572 Grade 50 provides higher
yield strength and may improve structural efficiency in properly engineered
applications.
The best choice depends on more than a single strength value. Engineers and
purchasers should evaluate thickness, product form, structural design,
stiffness, weldability, toughness, corrosion protection, availability and
total fabricated cost.
Before ordering, always confirm the governing material specification and
project requirements. The mill test certificate should match the steel grade,
plate dimensions and heat-number markings supplied with the shipment.
Request ASTM A36 or A572 Grade 50 Steel Plate
JUDE STEEL supplies carbon and alloy steel plate for construction, machinery,
infrastructure, energy and industrial fabrication projects. Available services
may include custom sizing, cutting, beveling, drilling, surface treatment,
inspection and export packaging.
Send us your required grade, thickness, width, length, quantity, destination
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