Issue 14

B. Lo ws by Kuhn e average st . 3 presents a is a material c

bato da Silva et and Hardrah ress about ch n obtained e onstant that

alii, Frattura ed t [3] became aracteristic l xpression by is a function

Integrità Struttu base for aver ength from r Kuhn and H of the tensile

rale, 14 (2010) age stress mo oot notch eq ardraht, whe strength.

36-44; DOI: 10 dels. This m uals the end re  is root n

.3221/IGF-ESIS.

14.04

rela fati sm not

tion. The fir gue failure o ooth specime ch opening a

st model sho ccur when th n S f . The Eq ngle, and A 1 K   ted the Eq. 3 th, S rt , for ste 1 K  1 t A w   

odel assumes urance limit otch radius,

the of a w is

(3)

1 f K  



  rt N a f S  i cording to E

s a constant m q. 5

can be quant

4 [4], where

aterial that

ified in func

Ne of

uber formula tensile streng

as the Eq. els with S rt

tion

>

550 MPa, ac

(4)

1 f K  

t

a

N

1





rt S 

134

586

(5) more than l ge stress mo n, where a P

N a 

10

distance d 0 fr n’s model is linearly. Th th according

occur when ]. Obviously ss near to no function of

Pet fati Ho con

erson assum gue strength wever, Peter stant materia

ed that the fa of a smooth son proposed l and it can b 1 K 

tigue failure specimen [5 that the stre e estimate in

the stress at , the Peterso tch decrease tensile streng

om root notc a particular e Eq. 6 expre to Eq. 7.

h is equal or case of avera ss this relatio

imit del. is a

(6)

S

,

1520MPa



1 f K  

t

P       a 

r

t

1



  

  

0      

700

rt S 

0,185

,

700

MPa



S

rt

(7)

P a 

1.8

  

  

207

9

S

00MPa

7

, 0254





,

rt

S

rt

E X

PERIMENT

AL PROCED

URE

Ma ten are T

terial

been used in hat it resist . 1. The mec lel-projected

he teste turbine properti

d material w components es according S rt , and yield ab. 2 and Ta

as a steel allo and it requ to ASTM A strength, S y .) b. 3, respectiv Mn .06  1.00 Table 1 : Che E (GP 198  Table 2 : Me

y, ASTM A ests high m 743/A 743 and fatigue ely. Si  1.00 11 mical properti (M 4 575  chanical prope a) S y C

743 CA6NM echanical str M [6] are sh properties ba omposition ( Cr Ni .5-14 3.5–4 es of ASTM A (MP 35 918  rties of ASTM Pa) S rt

, which has ength and t owed in Tab sed on Paral

the fabricat the corrosio hanical (You method acco

ion of hydra n. Its chem ng modulus rding to Silva

ulic ical , E , [7]

sile strength, showed in T

%)

C

Mo .5 0.4–1.0 743 CA6NM a) Hardnes 1 273.0  A743 CA6N

P  0.04  alloy steel [6]. s (HB) 7.0 M alloy steel.

S 0.03

 0

37