New Multiphase CP and DP 1000 MPa strength level grades for improved performance after hot forming

Pure martensitic steels have after hot forming limited performance in terms of rest ductility which limits the application in crash relevant parts. New steel grades were designed in the EU project HOTFORM including the corresponding process routes. These steel grades have ferritic-martensitic dual phase (DP) and martensitic-bainitic complex phase (CP) microstructures after hot forming process. The laboratory tests show an improved formability after hot forming. The basic concepts of the new alloys are explained. Furthermore, for validation of upscaling purposes a semi-industrial test is carried out and the results are discussed. The main application is for vehicle safety. This is evaluated by comparing the crash performance of these hot formed grades with cold rolled DP1000 and CP1000 for crash cans in a drop tower test.The research leading to these results was carried out in the framework of HOTFORM project with a financial grant of the Research Programme RFCS (Research Funds for Coal and Steel) under grant agreement (RFSR-CT-2015-00017)

MASS-POLARIZATION EFFECTS IN THE 1S2S 1S AND 3S STATES OF HELIUM

From a laser spectroscopic study of isotope shifts in the 1s2s 1S,3S1snp transitions in He3 and He4 and of the hyperfine structure in the 1snp Rydberg states of He3 we have derived highly accurate information on mass-polarization effects in the 1s2s 1S and 3S states. The experimental results, which are in good agreement with recent, high-precision variational calculations, confirm an isotope dependence of ;p1;p2;.. AE © 1990 The American Physical Society