Automotive high-strength steel types

The car body is one of the important components of the car. There are many types of steel materials involved in car body manufacturing, and different elements play different roles in these steel materials. The editor of GNEE STEEL will introduce the role of each element in automotive steel materials. This article introduces the commonly used bake-hardened steel (BH), high-strength low-alloy steel (HSLA) and high-strength interstitial-free steel (HSIF) for automobile bodies and the elements they contain:

High strength steel bake hardened steel plate

High-strength steel bake-hardened steel plate is a bake-hardened cold-rolled steel plate made from low carbon steel or ultra-low carbon steel by adding micro-alloying elements niobium, titanium or vanadium. It also has excellent deep drawing performance and baking High quality automotive sheet with hardening properties.
BH steel hardening principle

The strengthening of BH steel plates is achieved through solid solution strengthening. Due to the presence of solid solution carbon or nitrogen in the steel, dislocation occurs during stamping and forming. During the painting and baking process at about 170°C, the solid solution carbon interacts with the dislocation, causing the strength of the steel plate to increase, resulting in the effect of artificial strain age hardening. . The principle is the same as the deterioration phenomenon that occurred in low carbon steel in the past.

The BH steel plate is characterized by being soft and easy to form and process before stamping. The yield strength is increased through the painting and baking process after stamping, so it is very suitable for covering parts such as automobile exterior panels. low alloy high strength steel

HSLA
Low-alloy high-strength steel is strengthened by adding micro-alloying elements such as niobium, titanium, and vanadium singly or in combination to form carbonitride particles and precipitate them. At the same time, higher strength is obtained through the refinement of grains by micro-alloying elements, and this steel type has good welding performance.

Interstitial-free high-strength steel

Interstitial-free high-strength steel improves the plastic strain ratio (r value) and strain hardening index (n value) of the steel by controlling the chemical composition of the steel. Usually, phosphorus element, ultra-low carbon and micro-alloy are added to low carbon steel and ultra-low carbon steel to greatly improve the deep drawability, plasticity and toughness of phosphorus-containing high-strength IF steel, and the solid solution strengthening of phosphorus element The high strength of IF steel is guaranteed. Due to the solid solution strengthening of the elements in the steel and the interstitial-free microstructure, this steel has high strength and very good cold forming properties, and is often used to make complex parts that require deep drawing.

In addition, low carbon steel with good deep drawing performance is commonly used in the thin plate parts of automobile bodies. This kind of steel has high strength and ductility and is suitable for manufacturing car doors, hoods and other components.

The above introduces the commonly used bake-hardened steel (BH), low-alloy high-strength steel (HSLA) and interstitial-free high-strength steel (HSIF) steels for automobile bodies and the elements they contain. These steels play an important role in the manufacturing of automobile bodies. Through different element combinations and processing techniques, they achieve the high strength, lightweight and aesthetic requirements of the automobile body. With the development of the automobile industry and the continuous advancement of technology, it is believed that more high-quality steel materials and manufacturing processes will be applied to the manufacturing of automobile bodies in the future.