Calculated and experimental estimation of preliminary loading effect at elevated temperatures on fracture toughness of pressure vessel materials

Timofeev, B. T.; Smirnov, V. I.

doi:10.1016/0308-0161(94)00028-h

Cited by 10 publications

(2 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A review of fracture-mechanics publications [1][2][3][4][5][6][7][8][9][10][11] has revealed that for crack-containing bodies made of bcc-structured materials a promising method for improving their brittle fracture resistance is the plastic prestraining at an upper shelf of the fracture toughness vs. temperature curves.…”

Section: Introductionmentioning

confidence: 99%

A calculation-experimental study of crack-tip opening displacement and residual stresses upon warm prestressing

2011

View full text Add to dashboard Cite

V. N. EzhovFor a reactor pressure vessel steel 15Kh2MFA(III) experiments and calculations have been carried out to study the factors that have an influence on the increase of the lower-shelf fracture toughness in the temperature dependence diagrams upon warm prestressing. Stereoscopic fractography and numerical investigation have demonstrated that after the warm prestressing the crack tip remains blunt. This reduces the stress singularity during subsequent loading and raises the material fracture toughness. The paper gives the calculated data on residual stresses and crack-tip opening displacement during warm prestressing and upon relief. The calculated results are shown to agree well with the known analytical relations and experimental data.Keywords: warm prestressing, fracture toughness, heat-resistant reactor pressure vessel steels. Introduction.A review of fracture-mechanics publications [1][2][3][4][5][6][7][8][9][10][11] has revealed that for crack-containing bodies made of bcc-structured materials a promising method for improving their brittle fracture resistance is the plastic prestraining at an upper shelf of the fracture toughness vs. temperature curves.The available published data demonstrate that depending on the level of warm prestressing (WPS) there are three main factors that have an effect on the increase of brittle fracture toughness: (i) strain hardening, (ii) crack tip blunting, and (iii) residual compression stresses [1] (Fig. 1). However, the contribution of each of these factors to the increase of fracture toughness depending on the WPS level has not been adequately studied. Furthermore, the influence of factor such as the body geometry and dimensions (the scale effect) on the magnitude of fracture toughness upon WPS is still poorly understood. Ignoring these factors and disregarding the significant role of crack blunting that may take place upon WPS are the drawbacks of the Chell model [2] which has been widely used recently.It was shown in [5] that the applicability of the Curry model [3] was limited due to disregarded crack tip blunting and insignificant role of strain hardening. Thus, that approach is suitable for the cases where the relation of loads and displacements during WPS is close to linear.Reed and Knott [6] studied the contribution of crack tip blunting to the WPS effect. The warm-prestressed specimens were tempered to relieve residual stresses. The researchers observed a considerable decrease of fracture toughness and thus inferred that the contribution of the crack tip blunting was small. It should be mentioned that tempering results in a lower fracture toughness of non-WPS specimens too, and that the WPS level studied was such that the crack blunting was but insignificant and it was the residual stresses which made the major contribution to the increase of fracture toughness upon WPS.Despite the development of analytical models for predicting the WPS effect, insufficient consideration is given to the numerical analysis of this phenomenon. Nevertheless, there have been public...

show abstract

Section: Introductionmentioning

confidence: 99%

A calculation-experimental study of crack-tip opening displacement and residual stresses upon warm prestressing

2011

View full text Add to dashboard Cite

show abstract

“…The subject of the present study is initially isotropic materials. Some aspects of crack growth resistance of anisotropic materials were addressed in [17,[19][20][21][22][23]. The present paper examines the influence of plastic prestrain on the crack growth resistance and kinetics of orthotropic metallic materials subject to kinematic hardening under uniaxial cyclic tension (pulsating stress cycle).…”

mentioning

confidence: 99%

On fracture toughness of orthotropic metallic materials under cyclic loading

Bastun

2009

Int Appl Mech

View full text Add to dashboard Cite

A VT-6 titanium alloy rolled sheet, which is initially isotropic and subject to kinematic hardening, is used as an example to analyze the effect of kinematic hardening on crack growth resistance under uniaxial cyclic loading. Crack growth resistance is characterized by the number of cycles to failure, critical crack length, and critical stress intensity factor. The subject of study is plane specimens with an edge notch. It is shown that prestrain changes the anisotropy of the specimens, which is determined as the ratio of the crack growth resistance in the rolling direction to that in the transverse direction. The crack path under a load applied at an angle to the axes of anisotropy is studied Keywords: orthotropic material, kinematic strain hardening, crack growth resistance, uniaxial cyclic loading Introduction. The crack growth resistance of materials under cyclic loading depends on many factors such as temperature, loading frequency, stress cycle, ambient medium, stress state mode [4,6]. The effect of plastic prestrain on the strength and life of materials under cyclic loading is studied in [7,12,13,15]. The influence of these factors on crack growth resistance was examined in [1,10,11,18,22]. The subject of the present study is initially isotropic materials. Some aspects of crack growth resistance of anisotropic materials were addressed in [17,[19][20][21][22][23]. The present paper examines the influence of plastic prestrain on the crack growth resistance and kinetics of orthotropic metallic materials subject to kinematic hardening under uniaxial cyclic tension (pulsating stress cycle).Experimental Technique. The subject of study is VT-6 titanium alloy, which is orthotropic when in as-received condition [9]. Specimens for tests were made from plates produced by rolling. The mechanical properties of the material (yield strength s Y , ultimate strength s u , uniform component of residual elongation e p , Young's modulus E, and Poisson's ratio m)

show abstract

Influence of the modes of thermomechanical preloading on the resistance of heat-resistant steels to brittle fracture

Покровский¹,

Ivanchenko²

1999

Strength Mater

View full text Add to dashboard Cite

Calculated and experimental estimation of preliminary loading effect at elevated temperatures on fracture toughness of pressure vessel materials

Cited by 10 publications

References 10 publications

A calculation-experimental study of crack-tip opening displacement and residual stresses upon warm prestressing

A calculation-experimental study of crack-tip opening displacement and residual stresses upon warm prestressing

On fracture toughness of orthotropic metallic materials under cyclic loading

Influence of the modes of thermomechanical preloading on the resistance of heat-resistant steels to brittle fracture

Contact Info

Product

Resources

About