Relationship between Surface Residual Stress Fields and Hydrothermal Environment on Low Temperature Aging of 3Y-TZP

2007 ◽  
Vol 361-363 ◽  
pp. 755-758
Author(s):  
Junji Ikeda ◽  
Fumiaki Miyaji ◽  
Masaru Ueno ◽  
Giuseppe Pezzotti
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Low Temperature ◽  
Phase Stability ◽  
Surface Condition ◽  
Stress Fields ◽  
Material Surface ◽  
Aging Test ◽  
Low Temperature Aging ◽  
Temperature Aging

Phase stability of 3 mol% yttria stabilized polycrystalline zirconia ceramics (3Y-TZP) was evaluated by aging test in water vapor environment and Raman spectroscopic technique. In our previous study, it has been confirmed that phase stability was improved by controlling sintering temperature. In this study, we pointed our attention and evaluated the influence of surface conditions related to machining and to heat treatment, thus monitoring the changes in phase transformation fraction and residual stress on the material surface. From the results of aging test, an increase in monoclinic fraction was observed for grinded surfaces as compared with polished surfaces. Samples subjected to heat treatment after machining showed improved phase stability. A Vickers indentation print was also introduced on a 3Y-TZP surface, and the relationship between surface condition and low temperature aging was evaluated in the neighborhood of the print. We found that the residual stress fields induced in phase-transformed areas were enhanced during low temperature aging, and that phase stability was improved by heat treatment.

scholarly journals The effect of low temperature aging on the mechanical property & phase stability of Y-TZP ceramics

2009 ◽  
Vol 1 (3) ◽  
pp. 113 ◽  
Author(s):  
Hyung-Tae Kim ◽  
Jung-Suk Han ◽  
Jae-Ho Yang ◽  
Jai-Bong Lee ◽  
Sung-Hun Kim
Keyword(s):  
Mechanical Property ◽  
Low Temperature ◽  
Phase Stability ◽  
Low Temperature Aging ◽  
Temperature Aging

Effect of grain size on phase stability of monoclinic U–Nb alloy during low-temperature aging

2015 ◽  
Vol 465 ◽  
pp. 167-169 ◽  
Author(s):  
Yanzhi Zhang ◽  
Xinjian Zhang ◽  
Xianglin Chen ◽  
Guan Weijun ◽  
Xiaolin Wang
Keyword(s):  
Grain Size ◽  
Low Temperature ◽  
Phase Stability ◽  
Low Temperature Aging ◽  
Temperature Aging

Design Optimisation of a Ferritic Ring Weld Specimen Using FE Modelling

2009 ◽  
Author(s):  
Christopher M. Gill ◽  
Paul Hurrell ◽  
John Francis ◽  
Mark Turski
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Finite Element ◽  
Neutron Diffraction ◽  
Stress Field ◽  
Finite Element Modelling ◽  
Post Weld Heat Treatment ◽  
Stress Fields ◽  
Element Modelling ◽  
Weld Heat

This paper describes the design optimisation of an SA508 ferritic steel ring weld specimen using FE modelling techniques. The aim was to experimentally and analytically study the effect of post weld heat treatment upon a triaxial residual stress field. Welding highly constrained geometries, such as those found in some pressure vessel joints, can lead to the formation of highly triaxial stress fields. It is thought that application of post weld heat treatments will not fully relax hydrostatic stress fields. Therefore a ferritic multi-pass ring weld specimen was designed and optimised, using 2D finite element modelling, to generate a high magnitude triaxial stress field. The specimen thickness and weld-prep geometry was optimised to produce a large hydrostatic stress field and still allow efficient use of neutron diffraction to measure the residual stress. This paper reports the development of the test specimen geometry and compares the results of welding FE analysis and neutron diffraction measurements. Welding residual stresses were experimentally determined using neutron diffraction; both before post weld heat treatment. Three dimensional moving heat source weld finite element modelling has been used to predict the residual stresses generated by the welding process used. Finite element modelling examined the effect of phase transformation upon the residual stress field produced by welding. The relaxation of welding stresses by creep during post weld heat treatment has also been modelled. Comparisons between the modelled and measured as-welded residual stress profiles are presented. This work allows discussion of the effect of post weld heat treatment of triaxial stress fields and determines if finite element modelling is capable of correctly predicting the stress relaxation.

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