Choosing Between Q195 and Q235 Steel: Which is Better for Your Project?


Published on:

2023-12-01

Q235 steel, with its comprehensive mechanical properties encompassing strength, plasticity, toughness, and weldability, is a widely used carbon structural steel. Its versatile nature allows it to fulfill various general application requirements, resulting in a broad range of uses. Q195 finds common usage in manufacturing anchor bolts, ploughshares, chimneys, roof panels, rivets, low-carbon steel wires, thin plates, welded pipes, tie rods, hooks, brackets, and welded structures.

Choosing Between Q195 and Q235 Steel: Which is Better for Your Project?


I. Introduction about Q195 and Q235 Steel
A. Brief overview of Q195 and Q235 steel
B. The meaning of Q and “195/235”
C. What is Q235/Q195 steel grade equivalent to?

II. Specification and Properties
A. Q195 Steel
        1. What is the composition of Q195?
      2. Is that Q195 steel is good? 
      3.What is the yield strength of Q195 steel?

 B. Q235 Steel
        1. What is the composition of Q235? 
     2. Will Q235 steel rust?Mechanical strengths and properties (comparing to Q195 steel)
     3. What is the yield strength of Q235 steel?

III. Comparative Analysis
 A. Chemical Composition
 B. Mechanical Properties
 C. Feature

IV. Construction Application
Is Q235 steel good or bad?

V. Conclusion


I. Introduction about Q195 and Q235 Steel
A. Brief overview of Q195 and Q235 steel

Q195 and Q235 steel grades with distinct compositions and properties. Q195 wire typically contains a lower carbon content compared to Q235 wire, making it less ductile but more suitable for cold forming and welding due to its increased hardness. Q235 wire, on the other hand, has a slightly higher carbon content, offering improved strength and better flexibility, making it more ideal for general applications requiring higher tensile strength.

B. The meaning of Q and “195/235”

In the designation "Q195," the "Q" signifies the code for the yield point or limit of ordinary carbon structural steel. The numerical value "195" represents the yield point value in units of megapascals (MPa) or newtons per square millimeter (N/mm²). This numerical designation denotes the specific level of the steel's yield strength. In the case of Q195, the yield point of this grade of steel is 195 MPa (N/mm²), indicating the amount of stress the steel can withstand before deformation occurs. 

This designation emphasizes the yield strength of the steel. The number "235" specifically denotes the minimum yield strength of the steel, which has been tested and confirmed to be at least 235 megapascals (MPa). This yield strength measurement has been determined through testing with steel samples having a diameter equal to or less than 16 millimeters. The "Q235" designation thus highlights the steel's capability to resist deformation or yield under applied stress, indicating its strength and suitability for various structural and industrial applications.

C. What is Q235/Q195 steel grade equivalent to?

The Q235 steel can be substituted with equivalent materials that include:United States: ASTM A283 Gr. B (σs185),International standard: ISO: HR2(σs195),Former Soviet Union: гOCT: CT1Kп,Japanese JIS: SS330(SS34)(σs205),German DIN: St33,British BS: 040A10,French NF: A33.
Q235 steel is interchangeable with similar materials from different standards. Equivalent materials include A36 in the USA ASTM standard, Q235 in China's GB/T standard, and SS400 in the Vietnamese/Japanese JIS standard. These materials share similar mechanical properties and are often substituted for each other in various applications due to their comparable composition and performance characteristics. 


II. Specification and Properties
A. Q195 Steel
1. What is the composition of Q195?

Q195 is known for its relatively low carbon content, making it suitable for various cold-forming processes and welding applications in industries such as construction, manufacturing, and general structural components.

The table below lists Q195 material chemical composition.

Low-carbon structural steel chemical composition (mass fraction) (%)
Name Grade C Mn Si S P method of deoxidation
Q195   0.12 0.5 0.3 0.004 0.035 F/Z

2. Is that Q195 steel is good?        

Q195 steel possesses moderate mechanical properties. Its strength and hardness are suitable for various applications, but it's not considered high-strength steel. With a relatively low carbon content, Q195 steel offers fair ductility, weldability, and formability, making it suitable for cold-forming processes and welding. However, it might lack the strength required for more demanding structural applications compared to higher-grade steels. Its mechanical properties are adequate for various general purposes, such as manufacturing smaller components, pipes, wire rods, and construction materials. Choosing the suitability of Q195 steel depends on specific application requirements where moderate strength and good formability are sufficient.

3.What is the yield strength of Q195 steel?

The yield strength of Q195 steel is approximately 195 megapascals (MPa). This measurement indicates the amount of stress or load the steel can withstand before it starts to deform permanently, often referred to as the yield point. Q195 steel is known for its moderate yield strength, making it suitable for various applications that do not demand extremely high strength properties.

The table below lists Q195 material other properties.

Yield strength  195 megapascals (MPa)
Tensile strength from 315 to 430 MPa
Elongation   33-35%
Reduction in area approximately 50%
Hardness 55-75 HRB (Rockwell hardness scale B)

 

B. Q235 Steel
1. What is the composition of Q235? 

Q235 steel is a versatile material used in various structural and industrial applications due to its balanced composition and mechanical properties.

The table below lists Q195 material chemical composition.

Low-carbon structural steel chemical composition (mass fraction) (%)
Steel Grade Quality Grade C Si Mn P S Deoxidation Method
Q235 Q235A 0.22 0.35 1.40 0.045 0.050 Rimmed / Killed
Q235B 0.20 0.35 1.40 0.045 0.045 Rimmed / Killed
Q235C 0.17 0.35 1.40 0.040 0.040 Killed
Q235D 0.17 0.35 1.40 0.035 0.035 Exceptionally Killed

What is the difference about Q235A,Q235B,Q235C,Q235D?       

In the GB/T 700-2006 standard, Q235, a carbon structural steel, is categorized into four grades: A, B, C, and D based on metallurgical quality. Each grade has varying chemical compositions and impact temperatures. The sulfur content decreases successively from A to D, while the phosphorus content is the same for A and B, followed by C, and the least in D. Impact temperatures also differ among these grades: 

- Q235A: No impact test required
- Q235B: Impact testing required at temperatures above 20 degrees Celsius
- Q235C: Impact testing required at temperatures above 0 degrees Celsius
- Q235D: Impact testing required at temperatures above -20 degrees Celsius

These distinctions in chemical composition and impact temperatures within the Q235 grades aim to cater to different application requirements and environmental conditions.

2. Will Q235 steel rust?Mechanical strengths and properties (comparing to Q195 steel)

Q235 steel, like many carbon steels, is prone to rust or corrosion when exposed to moisture and oxygen. Its susceptibility to rust is relatively similar to Q195 steel due to their comparable compositions. However, Q235 steel typically offers slightly higher mechanical strengths than Q195 steel. Q235 possesses a higher yield strength of approximately 235 MPa compared to Q195's yield strength of around 195 MPa. Additionally, Q235 steel generally has a slightly higher carbon content and improved mechanical properties, making it somewhat more resistant to deformation and providing better tensile strength than Q195 steel. Yet, both Q195 and Q235 steels require protective measures, such as coatings or proper maintenance, to prevent rusting and maintain their mechanical properties over time.

3. What is the yield strength of Q235 steel?

The yield strength of Q235 steel is approximately 235 megapascals (MPa). This measurement represents the amount of stress or load the steel can withstand before it starts to deform permanently, known as the yield point. Q235 steel is recognized for its higher yield strength compared to some other grades, such as Q195, making it suitable for various structural and industrial applications where increased strength is required.

Q235 possesses additional properties worth noting. Allow me to make a chart for you.

Tensile Strength, Ultimate 400 – 550 MPa
Tensile Strength, Yield 250 MPa
Elongation at Break 20 %
  23 %
Modulus of Elasticity 200 GPa
Compressive Yield Strength 152 MPa
Bulk Modulus 160 GPa
Poissons Ratio 0.26
Shear Modulus 79.3 GPa
Density    7.85 g/cc

 


III. Comparative Analysis
 A. Chemical Composition

The compositions in the above table represent the typical elemental makeup of each steel grade, highlighting their slight differences in carbon, manganese, and phosphorus content.

Q235, with higher carbon and manganese content compared to Q195, generally exhibits increased strength and improved mechanical properties. This variation results in higher tensile strength and better overall performance, making Q235 more suitable for structural and industrial applications requiring higher strength levels. Conversely, Q195, with its lower carbon and manganese content, may have slightly lower strength and toughness compared to Q235 but is often preferred for applications where less strength is acceptable or where better formability and weldability are required.

B. Mechanical Properties

Including the above table,these differences in mechanical properties indicate that Q235 generally possesses higher yield and tensile strength, with slightly lower elongation compared to Q195. The varying properties make Q235 more suitable for applications requiring higher strength, while Q195 might be preferred for applications where better formability and weldability are desired over sheer strength.

C. Feature

Q195 Features:

Lower Carbon Content: Approximately 0.06-0.12%
Mild Strength: Yield strength around 195 MPa, suitable for less demanding applications.
Good Formability: Ideal for cold-forming processes due to its lower carbon composition.
Weldability: Offers good weldability, aiding in various manufacturing processes.

Q235 Features:

Slightly Higher Carbon Content: Approximately 0.12-0.20%
Higher Strength: Yield strength approximately 235 MPa, providing better tensile strength compared to Q195.
Balanced Properties: Offers a balance between strength and formability, suitable for structural and industrial applications.
Versatility: Used in various sectors due to its improved mechanical properties.

Therefore,Q195 is preferred for applications where moderate strength and excellent formability are crucial, like smaller components and structural elements. Q235, with its higher strength, finds use in structural and industrial applications requiring better strength and toughness.


IV. Construction Application
Is Q235 steel good or bad?

Q235 steel is generally considered good for construction applications due to its higher strength compared to some other grades, such as Q195. Q195 is suitable for less demanding construction purposes due to its moderate strength.Both Q195 and Q235 wire serve as excellent materials for construction purposes.Choosing between Q195 and Q235 in construction depends on the specific structural requirements, load considerations, and desired properties for the project. 


V. Conclusion

The plasticity of low-carbon steel grades like Q195 and Q235 increases with higher carbon and manganese content in their chemical composition.

Q235 steel possesses comprehensive mechanical properties including strength, plasticity, toughness, and weldability, making it a versatile carbon structural steel suitable for various applications. Its wide application range arises from meeting general use requirements.

Q195 steel finds application in manufacturing anchor bolts, ploughshares, chimneys, roof panels, rivets, low-carbon steel wires, thin plates, welded pipes, tie rods, hooks, brackets, and welded structures. Conversely, Q235 is commonly used in construction applications.

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