PSI - Issue 18

5 5 5 5

Ivica Čamagić et al. / Procedia Structural Integrity 18 (2019) 385 – 390 Author name / Structural Integrity Procedia 00 (2018) 000–000 Author name / Structural Integrity Procedia 00 (2018) 000–000 Author name / Structural Integrity Procedia 00 (2018) 000–000 Author name / Structural Integrity Procedia 00 (2018) 000–000

Table 8. Remaining exploitation period-crack in the HAZ (new PM side) Table 8. Remaining exploitation period-crack in the HAZ (new PM side) Table 8. Remaining exploitation period-crack in the HAZ (new PM side) Table 8. Remaining exploitation period-crack in the HAZ (new PM side)

389

Critical crack length, ac, mm Critical crack length, ac, mm Critical crack length, ac, mm Critical crack length, ac, mm

Initial crack length a0, mm Initial crack length a0, mm Initial crack length a0, mm Initial crack length a0, mm

Assumed crack length, a, m Assumed crack length, a, m Assumed crack length, a, m Assumed crack length, a, m

Number of cycles,  N Number of cycles,  N Number of cycles,  N Number of cycles,  N

Geometry term, Y Geometry term, Y Geometry term, Y Geometry term, Y

Stress range,  , MPa Stress range,  , MPa Stress range,  , MPa Stress range,  , MPa

Load case Load case Load case Load case

I I I I

5.58 6.01 6.45 6.51 5.58 6.01 6.45 6.51 5.58 6.01 6.45 6.51 5.58 6.01 6.45 6.51 5.58 6.01 6.45 6.51 5.58 6.01 6.45 6.51 5.58 6.0 6.45 6.5 5.58 6.01 6.45 6.51

0.01 0.02 0.03 0.01 0.02 0.03 0.01 0.02 0.03 . 1 0. 2 0. 3 0.032 0.032 0.032 0.01 0.02 0.03 0.01 0.02 0.03 0.01 0.02 0.03 . 1 0.02 0.03 0.032 0.032 0.032 0.032 . 32

70053 24775 12611 11382 70053 24775 12611 11382 70053 24775 12611 11382 70053 24775 12611 3015732 1066565 542903 489975 3015732 1066565 542903 489975 3015732 1066565 542903 489975 1382 30157 2 1066565 542903 489975

211 211 211 211

5 5 5 5 5 5 5 5

32 32 32 32 32 32 32 32

II II II II

46 46 46 46

* Applies in the case of initial crack length of 5 mm. In the case of a crack in the HAZ from the new PM side: C = 9.61  10-10. m = 2.47 * Applies in the case of initial crack length of 5 mm. In the case of a crack in the HAZ from the new PM side: C = 9.61  10-10. m = 2.47 * Applies in the case of initial crack length of 5 mm. In the case of a crack in the HAZ from the new PM side: C = 9.61  10-10. m = 2.47 * Applies in the case of initial crack length of 5 mm. In the case of a crack in the HAZ from the new PM side: C = 9.61  10-10. m = 2.47 Table 9. Remaining exploitation period-crack in the HAZ (exploited PM side) Table 9. Remaining exploitation period-crack in the HAZ (exploited PM side) Table 9. Remaining xploitation period-c ck in the HAZ (exploited PM side) Table 9. Remaining exploitation period-cr ck in the HAZ (exploited PM side)

Initial crack length a0, mm Initial crack length a0, mm Initial crack length a0, mm Initial crack length a0, mm

Critical crack length, ac, mm Critical crack length, ac, mm Critical crack length, ac, mm Critical crack length, ac, mm

Assumed crack length, a, m Assumed crack length, a, m Assumed crack length, a, m Assumed crack length, a, m 0.01 0.02 0.01 0.02 0.01 0.02 0.01

Number of cycles,  N Number of cycles,  N Number of cycles,  N Number of cycles,  N

Geometry term, Y Geometry term, Y Geometry term, Y Geometry term, Y

Stress range,  , MPa Stress range,  , MPa Stress range,  , MPa Stress range,  , MPa

Load case Load case Load case Load case

I I I I

5.58 6.01 6.21 6.39 5.58 6.01 6.21 6.39 5.58 6.01 6.21 6.39 5.58 6.01 6.21 6.39 5.58 6.01 6.21 6.39 5.58 6.01 6.21 6.39 5.58 6.01 6.21 .39 5.58 6.01 6.21 6.39

17470 17470 17470 17470 6554 4682 4005 6554 4682 4005 6554 4682 4005 6554 4682 4005 607655 227949 162859 139303 607655 227949 162859 139303 607655 227949 162859 139303 607655 227949 162859 139303

211 211 211 211

5 5 5 5 5 5 5 5

27 27 27 27 27 27 27 27

0.025 0.027 0.025 0.027 0.025 0.027 . 2 0.025 0.01 0.02 0.01 0.02 0.01 0.02 0.01 0.02 0.025 0.027 0.025 0.027 0.025 0.027 0.025 0.027 . 7

II II II II

46 46 46 46

* Applies in the case of initial crack length of 5 mm. In the case of a crack in the HAZ from the exploited PM side: C = 5.5  10-9. m = 2.33 * Applies in the case of initial crack length of 5 mm. In the case of a crack in the HAZ from the exploited PM side: C = 5.5  10-9. m = 2.33 * Applies in the case of initial crack length of 5 mm. In the case of a crack in the HAZ from the exploited PM side: C = 5.5  10-9. m = 2.33 * Applies in the case of initial crack length of 5 mm. In the case of a crack in the HAZ from the exploited PM side: C = 5.5  10-9. m = 2.33 4. Discussion Results shown in tables 5-9 indicate that the remaining work life of the reactor, i.e. the number of cycles Δ N until critical crack length is achieved, depends on:  Assumed crack length a ;  Allowed stress range,   , and  Crack initiation location The greater the assumed crack length and the range of allowed stress, the lower the number of cycles until the potential catastrophe and uncontrolled failure. Under the assumed working loads (stresses), equal to yield stress in exploitation conditions ( R p 0.2 = 211 MPa), the number of cycles needed to reach critical crack length is very low, tables 5-9. This was expected, having in mind that this is low-cycle fatigue, i.e. the acting loads are close to yield stress value, [5,7]. In the case when the assumed work load is real, i.e. the load determined by tensometry of the reactor, with a magnitude of 46 MPa, the number of cycles needed to reach critical crack length is considerably greater, since the stress levels are lower. However, despite the lower stresses, it is still above the fatigue threshold stress,  K th , and thus, assumed crack growth happens anyway, [3,7]. Furthermore, in this analysis, the location of the potential crack was also taken into account, in terms of whether it occurred in the PM, WM or HAZ. Additionally, the effect of exploitation time was analysed, i.e. it was determined whether the crack occurs in the new or exploited PM or HAZ from the new or exploited PM sides. The effects of heterogeneity of the structure of welded joint components is directly reflected on the fatigue crack growth rate, da/dN, i.e. it is directly related to certain Paris equation parameters, coefficient C and exponent m. Based on tables 5-9, for the case of real load of 46 MPa, it can be seen that: In the case that the initial crack (with a length of 5 mm) in the new PM reaches the critical length of 41 mm, the exploitation period is 25.7 years, whereas the period required for the initial crack of the same length in the exploited PM to reach the length of 29 mm is 4.6 years. In the case that the initial crack (5 mm) in the WM reaches the critical length of 63.5 mm, the exploitation period is 29.6 years. 4. Discussion Results shown in tables 5-9 indicate that the remaining work life of the reactor, i.e. the number of cycles Δ N until critical crack length is achieved, depends on: ssumed c ack length a ; Allowed stress range,   , and  Crack initiation location The greater the assumed crack length and the range of allowed stress, the lower the number of cycles until the potential atastrophe and uncontrolled failure. Under the assumed w king loads (stresses), equal to yield s ress in exploitation conditions ( R p 0.2 = 211 MPa), the number of cycles n eded o reach critical crack length is very low, tables 5-9. This was expected, having i mind that this is low-cycle fatigue, i.e. the acting loa s are close to ield str ss value, [5,7]. In the case when the assumed work load is real, i.e. the load determined by tensometry of the rea tor, wi h a magnitud of 46 MPa, th number of cycles need d to reach critical crack length is considerably greater, si ce the stress l vels are lower. However, despite the lower stresses, it is still above the fatigue threshold stress,  K th , and thus, assumed crack growth happens a yway, [3,7]. Fu thermore, in this analysis, the locati of the potential crack was also tak n into account, n terms of whether it occurr d in the PM, WM or HAZ. Additionally, the effect of exploitation time was analysed, i.e. it was determined wh ther the crack occurs in the n w or exploited PM or HAZ from th new or exploited PM sides. The effects of h terogeneity of the structure of welded joint components is directly reflected on the fatigue crack growth rate, da/dN, i.e. it is irec ly related t certain Paris quation parameters, coefficient C and exponent m. Based on tables 5-9, for the case of real load of 46 MPa, it can be seen that: In the case that the initial crack (with a length of 5 mm) in the new PM reaches the critical length of 41 mm, the exploitation period is 5.7 years, wh reas the period required for the initial crack of the same length in the exploited PM to reach the l ngth of 29 mm is 4.6 years. In the case that the initial crack (5 mm) in the WM reaches the critical length of 63.5 mm, the exploitation period is 29.6 years. 4. Discussion Results shown in tables 5-9 indicate that the remaining work life of the reactor, i.e. the number of cycles Δ N until critical crack length is achieved, depends on:  Assumed crack length a ;  Allowed stress range,   , and  Crack initiation location The greater the assumed crack length and the range of allowed stress, the lower the number of cycles until the potential catastrophe and uncontrolled failure. Under the assumed working loads (stresses), equal to yield stress in exploitation conditions ( R p 0.2 = 211 MPa), the number of cycles needed to reach critical crack length is very low, tables 5-9. This was expected, having in mind that this is low-cycle fatigue, i.e. the acting loads are close to yield stress value, [5,7]. In the case when the assumed work load is real, i.e. the load determined by tensometry of the reactor, with a magnitude of 46 MPa, the number of cycles needed to reach critical crack length is considerably greater, since the stress levels are lower. However, despite the lower stresses, it is still above the fatigue threshold stress,  K th , and thus, assumed crack growth happens anyway, [3,7]. Furthermore, in this analysis, the location of the potential crack was also taken into account, in terms of whether it occurred in the PM, WM or HAZ. Additionally, the effect of exploitation time was analysed, i.e. it was determined whether the crack occurs in the new or exploited PM or HAZ from the new or exploited PM sides. The effects of heterogeneity of the structure of welded joint components is directly reflected on the fatigue crack growth rate, da/dN, i.e. it is directly related to certain Paris equation parameters, coefficient C and exponent m. Based on tables 5-9, for the case of real load of 46 MPa, it can be seen that: In the case that the initial crack (with a length of 5 mm) in the new PM reaches the critical length of 41 mm, the exploitation period is 25.7 years, whereas the period required for the initial crack of the same length in the exploited PM to reach the length of 29 mm is 4.6 years. In the case that the initial crack (5 mm) in the WM reaches the critical length of 63.5 mm, the exploitation period is 29.6 years. 4. Discussion Results shown in tables 5-9 indicate that the remaining work life of the reactor, i.e. the number of cycles Δ N until critical crack length is achieved, depends on: ssumed c ack le th a ; Allowed stress range,   , and  Crack initia ion location The greater the assumed crack length and the r nge of allowed stress, the lower the n mber of cycles until the p tential atastr phe and uncontrolled failure. Under the assumed w king loads (st esses), equal to ield s ress in exploitation conditions ( R p 0.2 = 211 MPa), he number of cycles needed o reach critical c ack length is very low, tables -9. This was expec ed, having i mind that this is low-cycle fatigue, i.e. the ac ing loa s ar cl se to ield st ss value, [5,7]. In the case when th assumed work load is real, i.e. the lo d determined by tensometry of the rea tor, with a magnitud of 46 MPa, the number of cycles need d to reach critical crack length is con iderably greater, si ce the stress l vels re lower. However, despite the lower stresses, it is still above the fatigue threshold stress,  K th , and thus, assumed crack growth happens a yway, [3,7]. Fu thermore, in this analysis, the location of the potential crack was also tak n into account, in terms of whether it occurr d in the PM, WM or HAZ. Additionally, the effect of exploitation time was analysed, i.e. it was determined wh ther the crack occurs in the n w or exploited PM or HAZ from th new or exploited PM sides. The ffects of h terogeneity of the structure of welded joint compon nts is directly reflected on th fatigue crack growth rate, da/dN, i.e. it is irec ly r lated t certain Paris quation parameters, coefficient C and exponent m. Based on tables 5-9, for the c se of real load of 46 MPa, it can b s en that: In he case that the initial crack (with a length of 5 mm) in new PM reaches the critical leng of 41 mm, the exploitation period is 5.7 years, wh reas the period required for the initial crack of the same length in the exploited PM to reac the l ngth of 29 mm is 4.6 years. In the case that the initial crack (5 mm) in the WM reaches the critical length of 63.5 mm, the exploitation period is