New generation of cold rolled manganese boron steels now available for advanced automotive applications!

01.06.2022 | Salzgitter Flachstahl GmbH

The new cold-rolled grade 34MnB5 has been developed in close cooperation between Salzgitter Mannesmann Forschung GmbH and Salzgitter Flachstahl. This grade is a manganese-boron (MnB) alloyed heat-treatable steel.

Our extensive, in-depth know-how based on over 40 different products involving manganese-boron alloyed heat-treatable steels entered into the development. The CR1900T-MB-DS-UC complements the cold-rolled portfolio and complies with the requirements of Group standard VW 50066 and VDA239-500. Comprehensive characteristic values (according to SEP 1240 and SEP 1220, among others) as well as material data for numerical simulation are available and can be accessed at all times via the COMDaS material online portal. Work on the parameterization of a material model mapping the press hardening process harnessing the LS-DYNA software is currently being ongoing.

Manganese-boron alloyed, cold-rolled heat-treatable steels for press hardening have been specially developed for the automotive industry. The use of these steels enables advances in lightweight design and construction, while increasing occupant protection and also protecting the battery in the case of BEVs (Battery Electric Vehicles).

In many areas of car body construction, grade CR1500T-MB-DS-UC (22MnB5) has so far been the standard. In many places, CR1900T-MB-DS-UC will supplement or substitute this use.

In its as-delivered condition, the CR1900T-MB-DS-UC exhibits very good formability and is consequently also suitable for the cold forming of complex components. Manganese-boron steels only attain their final strength during hot forming and the associated controlled cooling in the die (press hardening). In hot forming, the microstructure of the initial blank is converted to the austenitic range under an inert gas atmosphere at around 950°C, after which the blank is formed directly. During cooling in the tool to temperatures between 100°C and 200°C, the material thereby acquires a martensitic microstructure, which greatly increases the tensile strength.

Thanks to the combination of formability and hardenability, this grade is particularly suitable for load-bearing and safety-relevant components such as A-pillar reinforcements, B-pillar reinforcements, sill reinforcements, floor cross members in BEVs, bumper cross members, roof cross members, etc.

Customers and users have already developed advanced technologies and applications for and with the CR1500T-MB-DS-UC, most of which can also be applied to the CR1900T-MB-DS-UC. At Salzgitter AG, various Group companies are joining forces in supporting customers in their respective implementation and development activities (Initiative Automotive). Salzgitter Europlatinen is the contact for Tailored Welded Blanks (TWB).
The new product has already been included in the draft standard VDA239-500 (May 2019).

C Mn Si Al Ti Cr B N
34MnB5 0.310 1.100 0.150 0.020 0.020 0.050 0.001 < 0,007
SZFG 0.390 1.500 0.350 0.045 0.055 0.250 0.005
Cr1900T- 0.300 ≤ 2,0 ≤ 0,8 0.010 Ti+Nb ≤ 0,50 0.001 ≤ 0,010
MB-DS1 0.380 0.080 ≤ 0,2 0.005
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Does all this sound interesting? Our sales and technical customer service department would be more than happy to assist you in selecting the appropriate material for your applications as well as providing the respective prototype material.