Effects of alloy additions and tempering temperature on the sag resistanceof Si-Cr spring steels

Citation
Wj. Nam et al., Effects of alloy additions and tempering temperature on the sag resistanceof Si-Cr spring steels, MAT SCI E A, 289(1-2), 2000, pp. 8-17
Citations number
27
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science","Material Science & Engineering
Journal title
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
ISSN journal
09215093 → ACNP
Volume
289
Issue
1-2
Year of publication
2000
Pages
8 - 17
Database
ISI
SICI code
0921-5093(20000930)289:1-2<8:EOAAAT>2.0.ZU;2-Y
Abstract
The effects of Mo, W, and V additions and tempering temperatures on the sag resistance in relation to the microstructural evolution during tempering o f Si-Cr spring steels were investigated by performing TEM examination, tors ional Bauschinger tests, hardness tests and tensile tests. The hysteresis l oop area measured in torsional Bauschinger tests, which is closely related with the sag resistance, is directly influenced by the distribution of prec ipitates. It increases and then decreases with tempering temperature, after reaching its maximum value at 350 degrees C. The additions of Mo and/or W result in a finer distribution of tempered carbide particles due to the dec rease in the rate of the spheroidization and of the coarsening of carbide p articles above 400 degrees C. However, they do not affect the behavior of t empered carbides at low tempering temperatures. Accordingly, the additions of Mo and/or W increase the hysteresis loop area at tempering temperature a bove 400 degrees C. The V addition increases the hysteresis loop area as we ll as hardness due to the precipitation of vanadium carbonitrides, regardle ss of tempering temperature. In considering industrial application of sprin g steels. a new parameter, the ratio of the hysteresis loop area in the tor sional Bauschinger test to hardness, is suggested. (C) 2000 Elsevier Scienc e S.A. All rights reserved.