Karpenko Physico-Mechanical InstituteKarpenko Physico-Mechanical Institute

Bay Zoltan Foundation for Applied Research Bay Zoltan Foundation for Applied Research

H.M. Nykyforchyn, O.Z. Student, G. Lenkey, A.D. Markov

STRENGTH OF POWER PLANT INSTALATIONS ELEMENTS AND

DURABILITY ANALYSIS BASED ON THE FRACTURE RISK

2nd Hungarian-Ukrainian Joint Conferenceon

SAFETY-REALIABILITY and RISK of

 ENGINEERING  PLANTS and COMPONENTS 19-21 September 2007, Kyiv, Ukraine

Introduction

Lifetime of structural element consists in:

at ambient temperatureCrack initiation stage → Crack propagation stage

at elevated temperatureMicrostructure change (because of diffusion) stage → Crack initiation stage → Crack propagation stage

Hydrogen intensifies diffusion and correspondingly accelerates microstructure change stage induced by diffusion processes

0 hours

190,000 hours110,000 hours

48,000 hours

Microstructure of the 12Kh1MF (0.1C-1.1Cr-0.26Mo-0.17V) steam Microstructure of the 12Kh1MF (0.1C-1.1Cr-0.26Mo-0.17V) steam pipeline steel depending of the service timepipeline steel depending of the service time

Tensile properties of the 12Kh1MF steel

op, hours

UTS, MPa

YS, MPa

, %

, %

H, MPa

0 470 280 29 75 1788

48000 436 237 33 66.4 1744

140000 453 251 27 77 1716

190000 460 258 25 77 17090 5 0 1 0 0 1 5 05 0

1 0 0

1 5 0

2 0 0

o p , 10 3 h

J, k

N/m

IS

The effect of operation time on fracture The effect of operation time on fracture toughness of the 12Kh1MF steeltoughness of the 12Kh1MF steel

0 50 100 150 2002,0

2,5

3,0

3,5

0 50 100 150 200 250 300

2

1

op, h

n, thermocycle

0 50 100 150 2002,0

2,5

3,0

3,5

0 50 100 150 200 250 300

2

1

op, h

n, thermocycle

K th

eff,

MP

am

1/2

0 50 100 150 2002,0

2,5

3,0

3,5

0 50 100 150 200 250 300

2

1

op, h

n, thermocycle

0 50 100 150 2002,0

2,5

3,0

3,5

0 50 100 150 200 250 300

2

1

op, h

n, thermocycle

K th

eff,

MP

am

1/2

Effect of the operation time Effect of the operation time орор (1) on the (1) on the parameter parameter Kth eff for the 12H1Kth eff for the 12H1ММF steelF steel

Fatigue crack growth rate across pipe wall at constant stress intensity factor range for steel after long term service

The method of high temperature degradation of steels -

thermocycling in hydrogenthermocycling in hydrogen

Microstructure of the 12Kh1MF (0.1C-1.1Cr-Microstructure of the 12Kh1MF (0.1C-1.1Cr-0.26Mo-0.17V)0.26Mo-0.17V) steam pipeline steel steam pipeline steel

depending of the numbers of thermocyclesdepending of the numbers of thermocycles

0 50 100 150 2002,0

2,5

3,0

3,5

0 50 100 150 200 250 300

2

1

op, h

n, thermocycle

0 50 100 150 2002,0

2,5

3,0

3,5

0 50 100 150 200 250 300

2

1

op, h

n, thermocycle

K th

eff,

MP

am

1/2

0 50 100 150 2002,0

2,5

3,0

3,5

0 50 100 150 200 250 300

2

1

op, h

n, thermocycle

0 50 100 150 2002,0

2,5

3,0

3,5

0 50 100 150 200 250 300

2

1

op, h

n, thermocycle

K th

eff,

MP

am

1/2

Effect of the operation time Effect of the operation time орор (1) (1)

and number of thermocycles in and number of thermocycles in hydrogen n (2) on the parameter hydrogen n (2) on the parameter

KKth effth eff for the 12H1 for the 12H1ММF steelF steel

Crack growth direction

Operation

Thermocycling

Hardness of steam pipeline weld joint of exploited 200,000h (on left) and in initial state (on right)

The mechanical properties of weld metal (WM) in virgin state (light bars) and The mechanical properties of weld metal (WM) in virgin state (light bars) and after after ~2∙105 ~2∙105 h service time (dark bars). h service time (dark bars).

Figures indicate a percentage change of properties as a result of exploitationFigures indicate a percentage change of properties as a result of exploitation

Ultimate strength (σB) and yield strength (σ0,2) of base metal and weld metal on air (light bars)

and after hydrogen charging (dark bars)initial service initial service

OMOMOM

OM BM→ ←

Hydrogenation allows to reveal even base metal “in-bulk” degradation

Comparison of the mechanical parameters of metal state concerning its sensitivity Comparison of the mechanical parameters of metal state concerning its sensitivity to high temperature degradation of weld metal (a) and base metal (b): to high temperature degradation of weld metal (a) and base metal (b): l – l – relative relative

change of the corresponded parameters as a result of servicechange of the corresponded parameters as a result of service

0 1 2 3 4 5 6 70

100

200

300

400

500

air

initial state 30 TC 100 TC

, M

Pa

, mm

100

5

12

15

R5

50

3 6

6

3 parent metal

cladded metal

The parent AThe parent A-516 -516 GrGr.60 .60 steel was cladded withsteel was cladded with 410 410S ferritic S ferritic stainless steel (flyer)stainless steel (flyer)

Peculiarities of hydrogen effect on the creep process in the Cr-Ni steel

H2

air

Fracture of hydrogenated specimenin as received state

Fracture of hydrogenated specimenin degraded state

ELECTROCHEMICAL PARAMETERSELECTROCHEMICAL PARAMETERS

steam pipeline 12Kh1MF steelsteam pipeline 12Kh1MF steel

0,0 0,2 0,4 0,6 0,8 1,0

0,2

0,4

0,6

0,8

1,0

Pd

egra

d /P

virg

in

J1C degrad

/J1C virgin

Rp

jcor

jE=const

190,

000

h

degraded

140,

000

virg

in s

tate

12Kh1MF - 3% NaCl

0,6 0,7 0,8 0,9 1,0

0,2

0,4

0,6

0,8

1,0

Pd

egra

d /P

virg

in

Kth degrad

/Kth virgin

jcor

Rp

jE=const

190,

000

h

140,

000

degraded

virg

in s

tate

12Kh1MF - 3% NaCl

0,4

0,6

0,8

1,012Kh1MF - tap water

degraded190000 hour

Pde

grad

ed/P

virg

indegraded

140000 hour

Ecor

ba

jcor

Rp

Risk Based Maintenance and Risk Based Maintenance and Inspection (RBMI) ApproachInspection (RBMI) Approach

Allocation of the thermal fatigue cracks around the hole on the internal surface of the collector of water economizer

Risk matrix for the economizer collector after 18∙104 h of service (area 4D) and its predicted state after performing of the recommended works

(area 3С)

ConclusionsConclusions

1. The thermocycling of the material containing dissolved hydrogen is the effective rapid method for testing of high temperature degradation of steels.

2. The parameters of crack growth resistance are especially sensitive to high temperature metal degradation in the service and laboratory conditions.

3. Weld metal of steam pipeline steel is the most disposed to high-temperature degradation. In this case the tensile mechanical properties of strength and plasticity are sensitive enough to “in-bulk” material degradation. The revealed simultaneous reduction of strength and brittle fracture resistance is a phenomenon of in-service degradation. This phenomenon is strengthened by non-typical change of the parameters of plasticity: an elongation increases and reduction of area decreases with the weld metal service.

4. Hydrogen accelerates creep rate in the hydrocracking reactor shell steel. 5. A good correlation between changes of electrochemical and mechanical

parameters gives prospects for the development of NDT methods for evaluation of the current state of steels irrespective of the fact that material is exploited or not exploited in corrosion-hydrogenated environments.

6. The example of a usage of Risk Based Maintenance and Inspection (RBMI) Approach is presented concerning the collector of water economizer.