Prediction of Type IV creep failure of a seam-welded mod. 9Cr-1Mo elbow based on microscopic damage simulation

2017 ◽  
Vol 34 (3) ◽  
pp. 194-207 ◽  
Author(s):  
Takuya Fukahori ◽  
Takumi Tokiyoshi ◽  
Toshihide Igari ◽  
Yasuharu Chuman ◽  
Nobuyoshi Komai
Keyword(s):  
Creep Failure ◽  
Type Iv ◽  
Microscopic Damage ◽  
Damage Simulation

GS18 Evaluation of Type-IV failure in Mod.9Cr steel welds based on micro-macro creep damage simulation

2011 ◽  
Vol 2011 (0) ◽  
pp. _GS18-1_-_GS18-3_
Author(s):  
T. FUKAHORI ◽  
F. KAWASHIMA ◽  
T. TOKIYOSHI ◽  
T. IGARI ◽  
Y. CHUMAN ◽  
...  
Keyword(s):  
Creep Damage ◽  
9Cr Steel ◽  
Type Iv ◽  
Steel Welds ◽  
Damage Simulation

scholarly journals Effect of Postweld Heat Treatments on Type IV Creep Failure in the Intercritical Heat-Affected Zone of 10% Cr Martensitic Steel Welded with Haynes 282 Filler

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 726
Author(s):  
Namkyu Kim ◽  
Yongjoon Kang ◽  
Jinhyeok Bang ◽  
Sangwoo Song ◽  
Seong-Moon Seo ◽  
...  
Keyword(s):  
Heat Affected Zone ◽  
Welded Joints ◽  
Martensitic Steel ◽  
Laves Phase ◽  
Lower Amount ◽  
Failure Behavior ◽  
Creep Life ◽  
Creep Failure ◽  
Type Iv ◽  
Postweld Heat

This study investigated the effect of postweld heat treatment (PWHT) conditions on Type IV failure behavior of 10% Cr martensitic steel welds using Haynes 282 filler. The welded joints were subjected to PWHT at temperatures of 688, 738, and 788 °C for 4 and 8 h. Creep tests were carried out at 600 °C under a stress of 200 MPa. The as-welded joint without PWHT showed Type IV cracking due to growth of voids around Laves phase by localized creep deformation in the intercritical heat-affected zone (ICHAZ). The creep properties of the PWHTed joints at 688 °C were similar to those of the as-welded joints without PWHT. On the other hand, the PWHTed joints at 738 °C exhibited a significantly longer creep life by a lower amount of Laves phase in the ICHAZ than those at 688 °C; this could be a result of the homogenization of ICHAZ microstructure during PWHT at 738 °C. However, the PWHT at 688 and 738 °C showed the same Type IV creep failure mode. Meanwhile, the PWHTed joints at 788 °C exhibited the shortest creep life in this study. The failure location was shifted to the base metal away from the HAZ, and severe plastic deformation occurred due to the softened matrix by excessive tempering.

scholarly journals Type IV Damage Evaluation for Mod.9Cr-1Mo Steel Welds Based on Microscopic Creep Damage Simulation

2012 ◽  
Vol 78 (789) ◽  
pp. 623-627 ◽  
Author(s):  
Takuya FUKAHORI ◽  
Takumi TOKIYOSHI ◽  
Toshihide IGARI ◽  
Yasuharu CHUMAN ◽  
Nobuyoshi KOMAI ◽  
...  
Keyword(s):  
Creep Damage ◽  
Damage Evaluation ◽  
Type Iv ◽  
Steel Welds ◽  
Damage Simulation

Creep Failure Behavior of Creep-Strength Enhanced Ferritic Steels

2004 ◽  
Author(s):  
F. Masuyama ◽  
N. Komai
Keyword(s):  
Creep Strength ◽  
Power Plants ◽  
Void Formation ◽  
Thick Wall ◽  
Failure Behavior ◽  
Ferritic Steels ◽  
Physical Damage ◽  
Creep Failure ◽  
Type Iv ◽  
Microstructural Morphology

Creep-strength enhanced ferritic steels such as Gr.92, Gr.122, Gr.23 and Gr.91 have recently been introduced for power plant applications, and some of these have experienced creep failure in boiler tubes and thick wall components after several years of operation. In order to use these steels safely in power plants, understanding of creep failure behavior is essential. In this study the creep failure of Gr.91 and Gr.92 boiler tube base metal and Type IV cracking of Gr.92, Gr.122, Gr.23 and Gr.91 welds were reproduced in test piece of actual components size. Creep failure mode was investigated, as was microstructural morphology during creep, particularly in the weldment, with discussion based on evidence of void formation and changes in the physical damage in terms of creep life.

scholarly journals Micro-Macro Combined Simulation of the Damage Progress in Low-Alloy Steel Welds Subject to Type IV Creep Failure

2004 ◽  
Vol 47 (3) ◽  
pp. 410-418 ◽  
Author(s):  
Fumiko KAWASHIMA ◽  
Toshihide IGARI ◽  
Takumi TOKIYOSHI ◽  
Akira SHIIBASHI ◽  
Naoya TADA
Keyword(s):  
Alloy Steel ◽  
Low Alloy Steel ◽  
Creep Failure ◽  
Type Iv ◽  
Combined Simulation ◽  
Steel Welds

Modelling creep failure in welded plates under uniaxial loading

1996 ◽  
Vol 31 (2) ◽  
pp. 117-124 ◽  
Author(s):  
R E Craine ◽  
M G Newman
Keyword(s):  
High Temperature ◽  
Damage Mechanics ◽  
Continuum Damage Mechanics ◽  
Approximate Solutions ◽  
Uniaxial Loading ◽  
Constant Thickness ◽  
Material Strength ◽  
Creep Failure ◽  
Damage Evolution Equation ◽  
Type Iv

Understanding more fully the behaviour of weldments is important since they can reduce the lifetime of structures at high temperatures, but performance factors are omitted from most existing design codes (with the exception of the high temperature fast reactor codes). Simple mathematical models which produce approximate solutions quickly are useful since they allow the design engineer to carry out rapid simulations. In this paper the ideas of continuum damage mechanics are incorporated into a model, based on the Cosserat theory of plates and a multi-axial version of Norton's creep law, which has been used recently to calculate the steady state creep strain rates in a weldment. Failure results are calculated numerically for a ferritic plate of constant thickness subject to uniaxial loading, the plate containing parent and weld metals, type IV material and a high-temperature heat-affected zone (HAZ). Results obtained for various material parameters and weldment configurations show that rupture times depend strongly on the choice of generalized stress in the damage evolution equation. The results also reveal that changes to the material strength of a region cannot be made in isolation if physically realistic results are to be obtained and, further, that early failures can occur if there are large differences in strength between the various parts of the weldment.

The LDE-Type Flare Occurrence (1969-1993)

1994 ◽  
Vol 144 ◽  
pp. 279-282
Author(s):  
A. Antalová
Keyword(s):  
Time Series ◽  
Fourier Analysis ◽  
Sunspot Cycle ◽  
List Type ◽  
Type Number ◽  
Solar Cycles ◽  
Type Iv ◽  
Long Duration ◽  
Cycle Maximum ◽  
Flare Index

AbstractThe occurrence of LDE-type flares in the last three cycles has been investigated. The Fourier analysis spectrum was calculated for the time series of the LDE-type flare occurrence during the 20-th, the 21-st and the rising part of the 22-nd cycle. LDE-type flares (Long Duration Events in SXR) are associated with the interplanetary protons (SEP and STIP as well), energized coronal archs and radio type IV emission. Generally, in all the cycles considered, LDE-type flares mainly originated during a 6-year interval of the respective cycle (2 years before and 4 years after the sunspot cycle maximum). The following significant periodicities were found:• in the 20-th cycle: 1.4, 2.1, 2.9, 4.0, 10.7 and 54.2 of month,• in the 21-st cycle: 1.2, 1.6, 2.8, 4.9, 7.8 and 44.5 of month,• in the 22-nd cycle, till March 1992: 1.4, 1.8, 2.4, 7.2, 8.7, 11.8 and 29.1 of month,• in all interval (1969-1992):a)the longer periodicities: 232.1, 121.1 (the dominant at 10.1 of year), 80.7, 61.9 and 25.6 of month,b)the shorter periodicities: 4.7, 5.0, 6.8, 7.9, 9.1, 15.8 and 20.4 of month.Fourier analysis of the LDE-type flare index (FI) yields significant peaks at 2.3 - 2.9 months and 4.2 - 4.9 months. These short periodicities correspond remarkably in the all three last solar cycles. The larger periodicities are different in respective cycles.

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