Examination of the effect of boron, titanium, zirconium, aluminium and nitrogen on weldable structural steels produced by quenching and tempering
A study was made of the mode of action of boron and of the influence upon it by Ti, Zr, Al and N in quenched and tempered weldable structural steels. The aim was to establish the relationships between the steel composition, transformation behaviour and microstructure, and the resulting mechanical properties. The objective was to attain a minimum yield strength of 700 N/mm2. Material examinations were performed on laboratory heats containing different alloy combinations. The findings revealed that any retardation of diffusional transformation, and thus any hardenability increase induced by boron, is achieved only if the nitrogen is almost completely fixed by potent nitride-forming elements such as Ti and Zr, and also the boron is present in the steel in a dissolved form. The use of Al in boron-alloyed steels produces practically no hardenability increase when compared with boron-free steels. It was found that a Ti-N ratio of 4 to 5 should not be exceeded and that Ti and N contents should be kept as low as possible when aiming for optimum strength and toughness in Ti-B-alloyed steels, after quenching and tempering.
Bibliographic Reference: EUR 13503 DE (1991) 115 pp., FS, ECU 11.25
ISBN: ISBN 92-826-2593-1
Record Number: 199111264 / Last updated on: 1994-12-02
Original language: de
Available languages: de