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Thermomechanical treatment to improve the fatigue behaviour of phosphorus containing high strength spring steels
Author(s) -
Wettlaufer Marc,
Kaspar Radko
Publication year - 2000
Publication title -
steel research
Language(s) - English
Resource type - Journals
eISSN - 1869-344X
pISSN - 0177-4832
DOI - 10.1002/srin.200001330
Subject(s) - tempering , fatigue limit , metallurgy , materials science , high strength steel , impurity , chemistry , organic chemistry
As a simulation of the manufacturing of parabolic leaf springs a conventional heat treatment (CHT) and two variants of thermomechanical treatment (TMT) were applied on a group of CrV high strength steels, without and with Nb‐microalloying. In a part of the steels the bulk concentration of phosphorus was increased above 0.02 %. The aim of the study was to determine fatigue properties for various tempering temperatures ϑ temp , especially of those steels contaminated with P. In a series of pretests the process parameters of CHT and TMT were optimized. After CHT a fatigue strength σ fat of between 750 and 825 MPa was established over a wide range of ϑ temp , rather independent of P content. But for the highest strength values ( R m ≥ 2100 MPa), produced at ϑ temp ≤ 280 °C, TMT performs the best fatigue properties (σ fat ≈ 900 MPa) superior to those after CHT. This study reveals that the advantageous effects of TMT can be reproduced even with impurity contaminated industrial grades.