SAPH400 Steel FAQS

What is SAPH400 steel?

SAPH400 steel is a hot-rolled steel for automobile structure produced by Baosteel. This steel adopts special production technology to deform inclusions, so that SAPH400 steel has good cold forming performance.

What is the microstructure of SAPH400 steel?

Metallographic structure of SAPH400 steel

The metallographic structure of SAPH400 steel is ferrite with a small amount of pearlite, and it has no obvious band structure.

SAPH400 steel is pure, uniform in structure and moderate in grain size. It is suitable for complex cold stamping processing. It has excellent comprehensive performance and can meet the needs of users. It is an ideal new material to replace ordinary carbon steel for the manufacture of vehicle frames.

What is the standard for SAPH400 steel?

Baosteel SAPH400 steel corresponds to the following standards:

varieties Baosteel enterprise standard fairly international standard use
Standard no. brand Standard no. brand
Automobile structure steel Q/BQB 310-


SAPH400 JIS G3113

JIS G3134

SAPH400 for formability car performance Components, wheels, etc.Vehicle Structural Parts

What are the chemical components of SAPH400 steel?

SAPH400 steel is a structural hot rolled steel in plate, sheet and strip form for automotive structural applications. The chemical composition of SAPH400 steel is given below.







What are the physical properties of SAPH400 steel?

SAPH400 steel is a structural hot rolled steel in plate, sheet and strip form for automotive structural applications. Structural Quality The tensile strength of hot rolled SAPH400 steel is more reliable than SAPH370 steel. It can be used in automotive applications where weight reduction is required. SAPH400 steel has good formability and ductility.

What are the mechanical properties of SAPH400 steel?

SAPH400 steel is a hot-rolled structural steel for body panels. The steel has increased tensile strength, yield strength and elongation compared to comparable unalloyed steels. For example, SAPH400 has a tensile strength of 440 MPa, while SPFH590 has a tensile strength of only 305 MPa. In addition, SAPH400 exhibits good weldability due to its low carbon content.

The specific mechanical properties are as follows:

brand Tensile test Bending test
Tensile strength Lower yield strength elongation
A1.8mm A
Nominal thickness
2.0-6.3 6.3-8.0 2.0-6.3 6.3-8.0 2.0-8.0
SAPH400 ≧400 ≧255 ≧235 ≧32 ≧26 a

What are the thermal properties of SAPH400H400 steel?

SAPH400 steel has good thermal properties, with a melting point of 1420-1460°C and a boiling point of 2040-2060°C. The specific heat capacity of SAPH400 steel is 0.49 kJ/kg K at 20 °C.

What is the production process of SAPH400 steel?

The production process route of SAPH400 steel: hot metal desulfurization pretreatment→converter blowing→slab continuous casting→slab surface inspection and treatment→slab heating→high pressure water descaling→hot continuous rolling→coiling→finishing→quality and performance inspection→ Packaging logo→delivery to warehouse.

What is the rolling process of SAPH400 steel?

According to the characteristics of SAPH400 steel, we have carried out process design from the aspects of heating system, rolling temperature and cooling system. The strength, plasticity and impact toughness of the coil are improved by adopting the method of fine graining.

  1. Heating system. The casting billet temperature is 1100~1150 degrees Celsius.
  2. Rolling system. Control the outlet temperature of the finishing stand at about 870 degrees Celsius.

Cooling regime. Due to the high strength requirements of SAPH400 steel, we adopt a lower coiling temperature, which will be set at 600 degrees Celsius.

What is the annealing of SAPH400 steel?

The main purpose of annealing is to eliminate internal stress in steel. This is especially important for SAPH440 steel used in body construction. By heating steel to high temperatures and then cooling it slowly, the internal stresses are released and the steel becomes more malleable and malleable. This allows it to be formed into complex shapes without cracking or breaking.

What is the converter process of SAPH400 steel?

  1. Control of the smelting end point: the smelting end point C is controlled at 0.035% ~ 0.045%, avoiding post-blowing and over-blowing, and improving the hit rate of one-time furnace failure.

(2) Control of the degree of deoxidation: the appropriate oxygen position after tapping should be controlled below 8×10-, and the corresponding steel [Als]>10-40

(3) Control of the amount of slag: The steel flow of tapping should be kept round and not scattered, and the amount of slag should be controlled below 5kg/t steel.

What is the refining process of SAPH400 steel?

(1) Control of slagging: Quickly create top slag with high alkalinity and good fluidity.

(2) Temperature control: target temperature ±15°C.

(3) Optimization of the wire feeding process: According to the incoming molten steel [Als], and referring to the average loss of acid-soluble aluminum of each steel type, determine the reasonable amount and time of adding Al wire.

(4) Control of acid-soluble aluminum in the refining process: Als≤5×10-4.

(5) Control of the composition of molten steel in the tundish: meet the target composition requirements of the steel grade, and the [Als] difference between adjacent heats is ≤5×10-.

What are the characteristics of SAPH400 steel?

The main characteristic of SAPH400 steel is its excellent machinability. This is a result of the material’s low carbon content and controlled rolling process. SAPH400 requires less cutting power and can be processed at higher speeds than other steels. As a result, manufacturing costs are significantly reduced.

In addition to excellent machinability, SAPH400 steel also has good weldability and formability. These properties make them ideal for a wide range of automotive applications.

SAPH400 steel has good comprehensive properties, especially excellent cold forming properties. The development of this steel grade has successfully solved the problem of cracking caused by insufficient elongation of traditional carbon steel during cold forming.





What is the application status of SAPH400 steel?

SAPH400 steel is mainly used to manufacture structural parts such as beams, longitudinal beams and corner braces of light vehicles, and can also be used to make formed structural parts and wheels that require high cold deformation performance.

Today, nearly 10,000 tons of SAPH400 steel has been produced, and it has been used by many well-known automobile manufacturers around the world to manufacture structural parts such as beams, longitudinal beams, and wheels of automobiles. Most users who have used SAPH400 steel reflect that the steel is pure, uniform in structure, moderate in grain size, suitable for complex cold stamping processing, has excellent comprehensive performance, and fully meets the requirements of users. It is an ideal new type of steel. Frame construction materials.