Steel Grades

3rd Generation Steels

First Generation Advanced High-Strength Steels (AHSS) are based on a ferrite matrix for baseline ductility, with varying amounts of other microstructural components like martensite, bainite, and retained austenite providing strength and additional ductility.

Bake Hardenable

Bake Hardenable (BH) steels grades are conventional High Strength Steels that exhibit a Bake Hardening Effect.

Carbon-Manganese (CMn)

Carbon and manganese are the two most cost-effective alloying additions to increase strength. While effective at strengthening, these additions reduce ductility and toughness, and make welding more challenging.

Case Studies in Alloy Selection

Automotive engineers have substantially more steel grades to select from in their quest to balance properties, performance, manufacturability, sustainability, and cost.

Complex Phase

Complex Phase (CP) steels combine high strength with relatively high ductility. The microstructure of CP steels contains small amounts of martensite, retained austenite and pearlite within a ferrite/bainite matrix.

Dual Phase

Dual Phase (DP) steels have a microstructure consisting of a ferritic matrix with martensitic islands as a hard second phase...

Ferrite-Bainite

Ferrite-Bainite (FB) steels are hot rolled steels typically found in applications requiring improved edge stretch capability, balancing strength and formability.

Grade Development Success Stories

Galvanizing of TRIP and 3rd Generation AHSS grades is particularly challenging. Manganese (Mn), aluminum (Al), and silicon (Si) are used in TRIP steel for strengthening, promoting austenite stability (Mn) and preventing cementite precipitation which indirectly enhances retained austenite stability (Si and Al).

High Strength Low Alloy Steel

Carbon-Manganese Steels (CMn) are a lower cost approach to reach up to approximately 280MPa yield strength, but are limited in ductility, toughness and welding.

Interstitial-Free High Strength

ULC, IF, VD-IF, and EDDS are interchangeable terms that describe the most formable (high n-value) and lowest strength grade of steel. Adding phosphorus, manganese, and/or silicon to these grades increases the strength due to solid solution strengthening, precipitation of carbides and/or nitrides, and grain refinement.

Low Density Steels

Low density steels are the collective name for some Fe-Mn-Al-C alloys.

Martensite

Martensitic steels are characterized by a microstructure that is mostly all martensite, but possibly also containing small amounts of ferrite and/or bainite...

Mild Steels

Mild steels are low carbon steels with no alloying elements added for substantial strengthening, and for that reason are characterized by relatively lower yield strength. Typically, mild steels have less than 0.10% carbon.

Press Hardening Steel Grades

Press hardening steels (PHS) are typically carbon-manganese-boron alloyed steels, specifically designed for hot forming process in the automotive industry.

Talk Like a Metallurgist

Every industry has its own jargon. In certain settings, these words might be necessary – you wouldn’t want a cardiologist talking to a gastroenterologist about boo-boos and upset tummies. But when these professionals talk with their patients, it’s sometimes necessary for them to use much simpler words. That is, assuming the goal is to actually communicate the issues and concerns.

Twinning Induced Plasticity

TWinning Induced Plasticity (TWIP) steels have the highest strength-ductility combination of any steel used in automotive applications, with tensile strength typically exceeding 1000 MPa and elongation typically greater than 50%.

Ultra-Low Carbon (DDS – EDDS)

ULC, IF, VD-IF, and EDDS are interchangeable terms that describe the most formable (high n-value) and lowest strength grade of steel.