Microstructural change of 9% Cr-welded joints after long-term creep

Sawada, Kota; Bauer, Mathias; Kauffmann, Florian; Mayr, P.; Klenk, Andreas

doi:10.1016/j.msea.2009.10.044

Cited by 54 publications

(25 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Their simulations showed good agreement with experimental studies and they concluded that the weak Type IV zone experiences no measureable constraint from adjacent stronger materials. Sawada et al [10] contributed to this discussion by investigating some of the fractured P911 cross-welds of this work using transmission electron microscopy (TEM), concluding that the higher multiaxiality of stress state in the center of the specimen did not affect the dislocation structure and the growth rates of M 23 C 6 carbides during creep. On the other hand, multiaxiality promoted the formation of Z-phase.…”

Section: Introductionmentioning

confidence: 79%

The Impact of Weld Metal Creep Strength on the Overall Creep Strength of 9% Cr Steel Weldments

Mayr

Mitsche

Cerjak

et al. 2011

Journal of Engineering Materials and Technology

View full text Add to dashboard Cite

In this work, three joints of a X11CrMoWVNb9-1-1 (P911) pipe were welded with three filler metals by conventional arc welding. The filler metals varied in creep strength level, so that one over-matched, one undermatched and one matched the creep strength of the P911 grade pipe base material. The long-term objective of this work was to study the influence of weld metal creep strength on the overall creep behavior of the welded joints and their failure mechanism. Uni-axial creep tests at 600°C and stresses ranging from 70 to 150 MPa were performed on cross-weld samples of all three welds. A total creep testing time of more than 470,000 hours was accumulated. The longest running sample achieved a time-to-rupture of more than 45,000 hours.Creep testing revealed that the use of under-matching weld metal led to premature fracture in the weld metal at higher stress levels. Compared to under-matching weld metal, the use of matching and over-matching filler material increased the time-to-rupture at high stress levels by 75% and 33% at lowest stress levels. At typical component stresses below 100 MPa, all samples failed in the grain-refined heat-affected zone by characteristic Type IV failure. For investigations of the failure modes, cross-sections of fractured samples were investigated by optical light microscopy, scanning electron microscopy and electron backscatter diffraction. The mechanism of weld metal creep failures and Type IV creep failures are discussed in detail.

show abstract

Section: Introductionmentioning

confidence: 79%

The Impact of Weld Metal Creep Strength on the Overall Creep Strength of 9% Cr Steel Weldments

Mayr

Mitsche

Cerjak

et al. 2011

Journal of Engineering Materials and Technology

View full text Add to dashboard Cite

show abstract

“…The creep rupture time in HAZ is approximately 1/5 of the parent material. The number of creep cavities per area increases with the creep damage process and the highest density of creep cavities is located in the mid-thickness (or the center of the fine-grained heat-affected zone) region which is about 60% creep damage rather than the surface region of the fine-grained heat-affected zone [18,[30][31][32][33]. The tri-axial stress state will accelerate the creep damage evaluation in the HAZ.…”

Section: P91 Steel Weldmentmentioning

confidence: 99%

“…The tri-axial stress state will accelerate the creep damage evaluation in the HAZ. However, it may not affect the growth and coarsening of precipitates rates during the creep phenomena [18,[30][31][32][33].…”

Section: P91 Steel Weldmentmentioning

confidence: 99%

Analyzing the Characteristics of the Cavity Nucleation, Growth and Coalescence Mechanism of 9Cr-1Mo-VNb Steel (P91) Steel

et al. 2013

AMR

View full text Add to dashboard Cite

Abstract. Creep damage is one of the serious problems for the high temperature industries and computational approach (such as continuum damage mechanics) has been developed and used, complementary to the experimental approach, to assist safe operation. However, there are no ready creep damage constitutive equations to be used for predicting the lifetime for this type of alloy, particularly for low stress. This paper presents an analysis of the cavity nucleation, growth and coalescence mechanism of 9Cr-1Mo-VNb steel (P91 type) under high and low stress levels and multi-axial stress state.

show abstract

“…Many of the reported results show that the microstructure of high-Cr steel changes during creep, indicating that the material strength of such steel is directly related to dislocations, precipitates and various interfaces of the lath boundary, subgrain boundary and prior austenite grain boundary [4][5][6][7][8][9]. However, to the author's knowledge, information on the effects of welding and damage degree on the microstructure of high-Cr steel weldment remains limited [10][11][12][13][14]. To clarify the degradation mechanism of high-Cr steel weldment, microstructural investigation taking such effects into account is certainly useful.…”

Section: Introductionmentioning

confidence: 99%

Microstructural change of a 9Cr steel longitudinal welded tube under internal pressure creep loading

Yamada

Yaguchi

Ogata

2013

Materials Science and Engineering: A

View full text Add to dashboard Cite

Microstructural change of 9% Cr-welded joints after long-term creep

Cited by 54 publications

References 15 publications

The Impact of Weld Metal Creep Strength on the Overall Creep Strength of 9% Cr Steel Weldments

The Impact of Weld Metal Creep Strength on the Overall Creep Strength of 9% Cr Steel Weldments

Analyzing the Characteristics of the Cavity Nucleation, Growth and Coalescence Mechanism of 9Cr-1Mo-VNb Steel (P91) Steel

Microstructural change of a 9Cr steel longitudinal welded tube under internal pressure creep loading

Contact Info

Product

Resources

About