Quality	Standard	Material No.	Possible Surface Coating:
HCT690T	DIN EN 10338	1.0947	+ZE according to DIN EN 10152 (electrolytically galvanized)
HCT690T	DIN EN 10346	1.0947	+Z, +ZF, +ZA (Hot-dip coating)

Testing direction	Yield point Rp0,2 (MPa)	Tensil Strength Rm (MPa)	Elongation A80 (in %)	Strain Hardening Exponent n 10-UE	Bake-Hardening-Index BH2
longitudinal test specimen	400 – 520	≥ 690	≥ 23	≥ 0,19	≥ 40

HCT690T is an advanced cold-rolled TRIP (Transformation-Induced Plasticity) steel specified according to the DIN EN 10338 standard. This steel type is known for its excellent combination of high strength and exceptional formability, making it especially suited for demanding industrial applications, particularly in the automotive industry. The unique microstructure of HCT690T, which includes both ferrite and retained austenite, enables the TRIP effect, giving it its outstanding mechanical properties.

HCT690T’s microstructure consists of a ferrite matrix that contains retained austenite. This composition is crucial for the TRIP effect (Transformation-Induced Plasticity), which occurs during deformation. The retained austenite is transformed into martensite through plastic deformation, increasing the steel’s strength while maintaining high ductility. HCT690T achieves a tensile strength of approximately 690 MPa, making it ideal for applications that require both high strength and excellent formability.

The production of HCT690T involves a precisely controlled process. First, the steel is hot-rolled and then cooled in a controlled manner to achieve the desired microstructure. A subsequent cold-rolling process refines the fine-grain structure and enhances the mechanical properties of the steel. A final heat treatment ensures the optimal balance between strength and ductility.

In addition to the cold-rolled version, HCT690T is also available as a continuously galvanized steel according to DIN EN 10346. The galvanization process involves continuously immersing the steel in a molten zinc or zinc alloy bath, forming a protective zinc coating on the surface of the steel. This coating provides excellent corrosion resistance, extending the lifespan of components and enhancing their performance in corrosive environments. Thus, the continuously galvanized version of HCT690T combines the mechanical advantages of TRIP steel with increased corrosion resistance.

HCT690T utilizes the TRIP effect, which is enabled by the special microstructure of the steel. The ferritic base structure contains retained austenite, which is transformed into martensite during plastic deformation. This transformation significantly improves the steel’s strength while maintaining ductility. The TRIP effect contributes significantly to the high energy absorption and crash safety of the material, making it particularly suitable for safety-critical applications in the automotive industry.

HCT690T is widely used in the automotive industry, where high material performance is required. Due to its high strength and excellent formability, this steel is particularly suitable for the production of body parts that need high energy absorption in the event of a collision. Examples include door reinforcements, bumpers, and safety cells. The continuously galvanized version of HCT690T is ideal for applications that require both mechanical performance and high corrosion resistance, such as exterior body parts and underbody components.

The production and application of HCT690T are carried out according to the strict guidelines of the DIN EN 10338 and DIN EN 10346 standards. These standards ensure that the steel meets high-quality and performance requirements. Regular inspections and checks throughout the production process guarantee that the steel’s mechanical properties and corrosion resistance are consistently maintained, ensuring its suitability for the intended applications.

With the growing demand for lighter, stronger, and more formable materials, particularly in the automotive industry, HCT690T is becoming increasingly important. Its ability to maximize the structural integrity of vehicles while reducing weight contributes to the development of more energy-efficient and safer vehicles. The continuous improvement of manufacturing processes and coating technologies will further optimize the properties of TRIP steels like HCT690T and open up new applications.

HCT690T offers an outstanding combination of strength, ductility, and corrosion resistance. Compliance with the DIN EN 10338 and DIN EN 10346 standards ensures consistent high quality and performance, making it a preferred choice for modern manufacturing processes.