GMW16579

Description / Abstract: This document describes the minimum process and internal testing requirements for producers of hot stamped parts.

Material Description. Hot stamping, or press hardening as it is also known, utilizes a steel of high hardenability such as 22MnB5 that is heated to convert the microstructure to austenite followed by stamping in a water cooled die to produce the proper part shape and to simultaneously quench the steel to create a martensite rich microstructure. Parts produced to this specification will have a uniform hardness and a microstructure consisting of primarily tempered martensite with allowable trace amounts (less than 5%) of nonmartensitic transformation products. Parts may also be specified to contain soft zones, which are lower strength than the surrounding metal and may not be fully martensitic in structure.

Symbols. Not applicable.

Applicability. Typical parts covered by this specification are those that require extremely high strength and are generally critical to passenger safety. These parts are found throughout the body structure and closures, with typical applications including but not limited to door beams, center pillar reinforcements, floor reinforcements, and upper body roof rails.