Application of cold rolled automotive sheets

Deep drawn steel plate
Deep drawing steel plates are mainly used to meet the deep drawing performance requirements of automotive steel. Uses and characteristics of deep drawn steel plates

Commercial grade (CQ)
Sufficient ductility for simple forming, bending or welding processes

Ordinary stamping grade (DQ)
It has greater ductility than commercial grade, more uniform molding and more complex deformation of parts.

Deep drawing grade (DDQ)
It has greater ductility and more uniform performance than ordinary stamping grades; it is suitable for manufacturing deep drawing forming and complex deformation parts.

Extra deep drawing grade (EDDQ)
It has greater ductility and more uniform performance than the deep drawing grade, and is suitable for manufacturing ultra-deep drawing and more complex deformed parts.

Extra deep drawing grade (S-EDDQ)
It has better stamping performance than the ultra-deep drawing grade, and is suitable for manufacturing ultra-deep drawing and extremely complex deformed parts. In order to meet the higher requirements for deep drawing performance of automotive steel, interstitial-free steel (IF steel) has been developed and applied in recent years. It is added with a certain amount of ultra-low carbon steel (C＜0.005%, N＜0.003%). The Ti and Nb in the steel fix the C and N atoms into carbides and nitrides, and there are no interstitial atoms in the steel.

This steel has excellent formability, that is, high plastic strain ratio r value (r>2.0), high work hardening index n value (n>0.25), high elongation δ (δ>50%) and non-aging ( AI=0), this steel type can be widely used in various automotive parts that have special requirements for deep drawing properties, such as oil pans or outer panels, etc.

Currently, GNEE uses IF steel plates and adopts continuous annealing process to produce and develop special ultra-deep drawing grade S-EDDQ steel plates. Its r value can be as high as 2.5, realizing industrial production.