Mild Steel

Types and Families of Mild Steel for Industrial Use

Mild steel, or low-carbon steel, is categorized based on its composition, mechanical properties, and intended applications. Its versatility makes it suitable for various industrial uses, from construction and manufacturing to automotive and household applications. Mild steel types differ primarily in carbon content and structural properties, influencing their strength, ductility, and machinability. Below are the primary families of mild steel and their unique properties and uses.

Carbon-Manganese Steel

Carbon-Manganese steel is one of the most common types of mild steel, characterized by its higher manganese content, which improves its strength and wear resistance. This type of steel is more robust and can handle significant stress, making it suitable for applications that require a stronger metal but don’t necessarily need higher carbon content.

• Typical Applications: Construction beams, structural supports, pipelines
• Properties: Enhanced strength, good ductility, moderate corrosion resistance

High-Strength Low-Alloy (HSLA) Steel

High-Strength Low-Alloy (HSLA) steel contains a small amount of additional alloying elements, such as copper, nickel, or chromium, to increase strength and toughness. This family of mild steel provides a high strength-to-weight ratio, ideal for load-bearing structures and heavy machinery.

• Typical Applications: Structural frames, automotive parts, bridges, and infrastructure
• Properties: High strength, good formability, enhanced resistance to corrosion and wear

Low-Carbon Steel

Low-carbon steel, often termed “mild steel,” contains the lowest carbon content (0.05%-0.25%), making it extremely ductile and easy to work with. It is suitable for applications requiring malleability and weldability, though it has limited strength compared to higher-carbon varieties.

• Typical Applications: Household appliances, car bodies, pipelines, and furniture
• Properties: High ductility, easy to weld and shape, low strength, susceptible to rust if untreated

Medium-Carbon Steel

Medium-carbon steel has slightly higher carbon content than low-carbon steel, offering a balance between strength and ductility. This family is often used where durability and impact resistance are required, though it is somewhat less ductile than lower-carbon steels.

• Typical Applications: Automotive parts, machinery, railway tracks
• Properties: Improved strength and hardness, moderate ductility, less weldable than low-carbon steel

Rebar Steel (Reinforcing Bars)

Rebar steel is specifically manufactured for use in reinforced concrete and masonry structures. It is often produced with specific patterns on the surface to improve adherence to concrete, providing structural stability in construction projects.

• Typical Applications: Reinforced concrete in buildings, bridges, and infrastructure
• Properties: High tensile strength, surface patterning for better adherence, designed for concrete reinforcement

Comparison Table of Mild Steel Types

Mild Steel Type	Carbon Content	Strength	Ductility	Applications
Carbon-Manganese Steel	Low	High	Moderate	Structural supports, pipelines
HSLA Steel	Low, with alloys	Very High	Moderate	Bridges, infrastructure, automotive
Low-Carbon Steel	0.05%-0.25%	Moderate	High	Appliances, car bodies, furniture
Medium-Carbon Steel	0.25%-0.5%	High	Moderate	Machinery, railway tracks
Rebar Steel	Low	High (tensile)	Moderate	Reinforced concrete structures

Stainless Steel Grades and International Equivalents Chart

Understanding mild steel grades and their international equivalents helps ensure that materials meet industry standards across regions. Different grading systems, including ASTM, EN, and JIS, categorize mild steel based on properties like strength, carbon content, and ductility. This chart provides an at-a-glance comparison of common mild steel grades and their equivalents, facilitating cross-reference and compatibility for global applications.

Mild Steel Grade	ASTM	EN	JIS	Description
Low Carbon Steel	A36	S235JR	SS400	General-purpose mild steel, good weldability and formability
High Strength Low Alloy (HSLA) Steel	A572 Grade 50	S355J2	SM490YB	High-strength, improved corrosion resistance
Carbon-Manganese Steel	A283 Grade C	S275JR	SS330	Moderate strength, suitable for construction applications
Medium Carbon Steel	A516 Grade 60	C45	S45C	Balanced strength and ductility, used in machinery and gears
Rebar Steel	A615 Grade 60	B500B	SD490	Reinforcing bars for concrete structures
Structural Steel	A992	S355	SM490A	High strength for structural support in construction
Pipe Steel	A53	S195T	STK400	Suitable for water, gas, and oil piping systems
Pressure Vessel Steel	A285 Grade C	P235GH	SPV235	Used in pressure vessels and boilers
Shipbuilding Steel	A131 Grade A	S235G1	KA32	Suitable for shipbuilding and marine environments

Complete EN Mild Steel Grades and Specifications Chart

European Norm (EN) standards categorize mild steel based on properties like strength, weldability, and intended applications. These standards help ensure that mild steel products meet industry requirements, promoting consistency and reliability across industries. This chart provides detailed specifications of common EN mild steel grades, including their mechanical properties and typical uses.

EN Grade	Designation	Tensile Strength (MPa)	Yield Strength (MPa)	Applications
S235JR	EN 10025-2	360-510	≥235	General construction, structural frameworks, machinery
S275JR	EN 10025-2	370-530	≥275	Building supports, bridges, machinery, and automotive parts
S355JR	EN 10025-2	470-630	≥355	Heavy-duty structural work, construction, industrial machines
C45	EN 10083-2	570-700	≥280	Medium-carbon steel, used for gears, machinery parts
S275J2	EN 10025-2	370-530	≥275	Structural engineering, load-bearing applications
S355J2	EN 10025-2	470-630	≥355	High-strength components, infrastructure, and mining
DC01	EN 10130	270-410	≥140	Cold-rolled steel for forming, used in automotive panels
DD11	EN 10111	270-410	≥170	Hot-rolled steel for deep drawing and forming
P235GH	EN 10028-2	360-500	≥235	Pressure vessels and boilers
P265GH	EN 10028-2	410-570	≥265	Boiler construction, pressure vessels
S355MC	EN 10149-2	420-520	≥355	High-strength steel for cold forming, automotive chassis
S420MC	EN 10149-2	480-620	≥420	Advanced engineering, load-bearing automotive parts

Comprehensive ASTM Mild Steel Grades and International Equivalents

The American Society for Testing and Materials (ASTM) has established a grading system widely used in the U.S. and globally. ASTM mild steel grades are defined by mechanical properties, carbon content, and specific applications, allowing industries to select the appropriate material for construction, manufacturing, and industrial projects. Below is an extensive chart of ASTM mild steel grades, aligned with EN and JIS standards for ease of international compatibility.

ASTM Grade	Designation	EN Equivalent	JIS Equivalent	Tensile Strength (MPa)	Yield Strength (MPa)	Applications
A36	Low Carbon Steel	S235JR	SS400	400-550	≥250	General construction, structural frameworks
A283 Grade C	Low to Medium Carbon	S275JR	SS330	380-515	≥205	Structural applications, tanks, and pipes
A516 Grade 60	Pressure Vessel Steel	P265GH	SPV235	415-550	≥220	Boilers, pressure vessels, industrial storage
A572 Grade 50	High-Strength Low-Alloy	S355J2	SM490	450-620	≥345	Bridges, heavy construction, infrastructure
A992	Structural Steel	S355	SM490A	455-620	≥345	Load-bearing structures, building frameworks
A53	Pipe Steel	S195T	STK400	330-485	≥205	Water, gas, oil pipes
A285 Grade C	Pressure Vessel Steel	S235JR	SPV235	380-515	≥205	Industrial tanks, low-pressure vessels
A131 Grade A	Shipbuilding Steel	S235G1	KA32	400-520	≥235	Shipbuilding, offshore structures
A656 Grade 80	HSLA Steel	S500MC	–	550-700	≥550	Heavy equipment, truck frames, industrial machinery
A709 Grade 50	Structural Bridge Steel	S355J2	–	450-620	≥345	Bridges, structural supports, infrastructure

Mild Steel Grades Chemical Composition Chart

The chemical composition of mild steel grades affects their properties, including strength, ductility, and weldability. Mild steel typically contains a low amount of carbon and a balance of other elements that influence performance in various applications. The chart below outlines the chemical composition of common mild steel grades, showing the percentage of elements like carbon (C), manganese (Mn), sulfur (S), phosphorus (P), and silicon (Si).

Grade	Carbon (C)	Manganese (Mn)	Sulfur (S)	Phosphorus (P)	Silicon (Si)	Other Elements	Applications
A36	≤ 0.26%	0.60-0.90%	≤ 0.05%	≤ 0.04%	≤ 0.40%	–	Structural frames, bridges, tanks
A283 Grade C	≤ 0.24%	0.90-1.20%	≤ 0.04%	≤ 0.04%	≤ 0.15%	–	Low-pressure vessels, tanks
A516 Grade 60	≤ 0.21%	0.60-1.20%	≤ 0.03%	≤ 0.04%	≤ 0.30%	–	Boilers, pressure vessels
A572 Grade 50	≤ 0.23%	0.50-0.60%	≤ 0.04%	≤ 0.04%	≤ 0.40%	Vanadium, Niobium	Bridges, heavy structures
S235JR	≤ 0.17%	1.00-1.20%	≤ 0.045%	≤ 0.045%	≤ 0.30%	–	General construction, framework
S275JR	≤ 0.21%	1.20-1.50%	≤ 0.045%	≤ 0.045%	≤ 0.35%	–	Building supports, automotive parts
S355J2	≤ 0.22%	1.00-1.60%	≤ 0.045%	≤ 0.045%	≤ 0.50%	–	Heavy-duty structures, mining
C45	0.42-0.50%	0.50-0.80%	≤ 0.04%	≤ 0.04%	≤ 0.40%	–	Machinery, gears, automotive parts
SS400	≤ 0.25%	0.50-1.00%	≤ 0.05%	≤ 0.05%	≤ 0.35%	–	Structural engineering, bridges
SPHC	≤ 0.15%	0.40-0.60%	≤ 0.05%	≤ 0.04%	≤ 0.04%	–	Automotive parts, piping

Mild Steel Grades Mechanical Properties

The mechanical properties of mild steel grades, including tensile strength, yield strength, and elongation, determine their suitability for various applications. These properties impact the material’s ability to withstand stress, deform under pressure, and remain durable in structural and industrial applications. Below is a chart detailing the mechanical properties of common mild steel grades.

Grade	Tensile Strength (MPa)	Yield Strength (MPa)	Elongation (%)	Applications
A36	400-550	≥250	20-23	General construction, frames, bridges, tanks
A283 Grade C	380-515	≥205	20	Structural applications, low-pressure vessels
A516 Grade 60	415-550	≥220	21-25	Boilers, pressure vessels, industrial storage
A572 Grade 50	450-620	≥345	18-20	Bridges, heavy construction, infrastructure
S235JR	360-510	≥235	24-26	Construction frameworks, machinery
S275JR	370-530	≥275	21-23	Building supports, automotive components
S355J2	470-630	≥355	18-20	Heavy-duty structures, mining applications
C45	570-700	≥280	16-19	Machinery, gears, automotive components
SS400	400-510	≥245	20-22	Structural engineering, bridges
SPHC	270-410	≥140	28-30	Automotive parts, piping, general forming

Thermal Properties of Mild Steel by Grade

The thermal properties of mild steel, including thermal conductivity and the coefficient of thermal expansion, play a crucial role in applications exposed to varying temperatures. These factors influence the material’s ability to conduct heat and expand or contract, impacting its performance in high-heat environments such as automotive, manufacturing, and structural engineering.

Grade	Thermal Conductivity (W/m·K)	Coefficient of Thermal Expansion (μm/m·°C)	Applications
A36	50	12.0	Structural frames, bridges, tanks
A283 Grade C	46	11.7	Low-pressure vessels, general construction
A516 Grade 60	40	11.9	Boilers, pressure vessels, storage tanks
A572 Grade 50	45	12.2	Infrastructure, heavy machinery, bridges
S235JR	50	12.0	Construction frameworks, automotive parts
S275JR	46	11.8	Structural supports, building frameworks
S355J2	37	12.5	Heavy-duty structures, mining equipment
C45	47	11.5	Machinery components, gears, automotive parts
SS400	51	12.1	Engineering structures, piping systems
SPHC	54	12.3	Automotive parts, industrial piping

Mild Steel Grades Hardness Comparison

The hardness of mild steel grades, typically measured using Rockwell, Brinell, and Vickers scales, indicates their resistance to indentation and wear. Hardness is a critical factor in applications requiring durability and wear resistance, such as machinery components, structural elements, and automotive parts.

Grade	Rockwell Hardness (HRB)	Brinell Hardness (HB)	Vickers Hardness (HV)	Applications
A36	55-75	120-160	130-180	Structural frames, bridge components, tanks
A283 Grade C	50-70	100-130	110-150	Low-stress applications, pressure vessels
A516 Grade 60	60-80	140-180	150-190	Boilers, pressure vessels, storage tanks
A572 Grade 50	65-85	135-160	140-170	Heavy construction, infrastructure, bridges
S235JR	55-70	120-160	130-160	Construction frameworks, automotive applications
S275JR	60-80	125-175	135-180	Structural supports, building frameworks
S355J2	70-90	150-190	160-200	Heavy-duty structures, industrial machinery
C45	85-100	170-210	180-220	Gears, automotive parts, machinery components
SS400	60-80	125-160	130-170	Engineering structures, piping
SPHC	45-65	110-140	120-150	Automotive parts, industrial applications

Applications of Mild Steel Grades Across Industries

Mild steel, known for its versatility, affordability, and ease of fabrication, is a widely used material across various industries. The unique properties of each mild steel grade make it suitable for specific applications, ensuring durability, cost-efficiency, and structural integrity in diverse sectors.

Grade	Applications	Industry	Reason for Use
A36	Structural beams, building frames, bridges, tanks	Construction	High weldability and strength for structural stability
A283 Grade C	Pressure vessels, low-stress structural components, general fabrication	Manufacturing	Good formability and moderate strength, suitable for pressure applications with low-stress requirements
A516 Grade 60	Boilers, storage tanks, pressure vessels	Energy and Industrial Storage	Resists high temperatures, suitable for high-pressure environments
A572 Grade 50	Bridges, large structures, heavy equipment frames	Infrastructure and Construction	High strength-to-weight ratio, excellent load-bearing capacity
S235JR	General structural applications, automotive components, light machinery	Automotive and Construction	Cost-effective and versatile, provides adequate strength for light-duty applications
S275JR	Building frameworks, reinforced structures, automotive frames	Construction and Automotive	Good balance of strength and ductility, suitable for support structures and frameworks
S355J2	Mining equipment, heavy machinery, structural components	Mining and Industrial Machinery	High strength and toughness, suitable for demanding environments with heavy load requirements
C45	Gears, shafts, automotive parts, mechanical components	Automotive and Engineering	Higher carbon content provides increased hardness and wear resistance for moving parts
SS400	Structural engineering components, bridges, general-purpose piping	Construction and Engineering	Versatile and affordable, suitable for general structural applications where moderate strength is sufficient
SPHC	Automotive parts, piping, stamped parts	Automotive and Manufacturing	Excellent formability, ideal for applications requiring shaping, stamping, and forming

Industry-Specific Examples of Mild Steel Applications

• Construction: Mild steel grades like A36 and S275JR are commonly used in building structural frames, bridges, and reinforcements due to their strength and affordability.
• Automotive: Grades such as C45 and S235JR are chosen for automotive parts, including frames, shafts, and body components, offering a balance of strength, formability, and durability.
• Energy and Industrial Storage: A516 Grade 60 is preferred for boilers and pressure vessels due to its resistance to high temperatures and pressures.
• Manufacturing: Mild steel sheets and coils, particularly A283 Grade C, are used for manufacturing stamped parts, equipment casings, and general-purpose applications due to their machinability and formability.
• Mining and Heavy Machinery: S355J2 is ideal for equipment used in mining and heavy industrial applications, where components are exposed to high stress and rugged conditions.