TECHNICAL PAPER

Simplicity, Consistency and Conservatism of Some Recent CharpyEnergy–Fracture Toughness Correlations in Estimatingthe ASTM E-1921 Reference Temperature

P. R. Sreenivasan

Received: 17 February 2011 / Accepted: 21 June 2011 / Published online: 1 December 2011

� Indian Institute of Metals 2011

Abstract After examining some recent Charpy energy–

fracture toughness correlations, a mean-2 procedure (M2P)

has been proposed for estimation of reference temperature,

T0, from CVN tests alone and has been established through

a correlative approach. The T0 estimate from the M2P is

referred as, TQ-M2, and is obtained as the mean value of two

different estimates discussed in the text. Simplicity, con-

sistency and assured conservatism of the TQM2 has been

demonstrated by comparison with measured T0 values for

some new steels. For the larger conservative estimate, it is

suggested to take the larger of the two and this, in most

cases happens to be the simple estimate, TQ41b, and is the

same as T41J (the 41 J Charpy energy temperature). The

applicability of the M2P for irradiated steels has been

demonstrated. A new two-parameter correlation for esti-

mating fracture toughness from Charpy energy has been

derived and this gives encouraging results for the steels

discussed in this paper.

Keywords Reference temperature � Charpy correlation �Master curve (MC) � Mean-2 procedure (M2P)

1 Introduction

Recently, the author had examined some of the previous

Charpy energy–fracture toughness correlations along with

some new correlations for their effectiveness in accurately,

yet conservatively, estimating the ASTM E-1921 reference

temperature, T0 [1, 2]. In conclusion, a mean-4 procedure

(M4P) was proposed. The simplest correlation was shown

to be that based on the T41J temperature while a conser-

vative correlation based on the T28J temperature was also

provided; while the former was consistent, the latter

showed erratic behavior and scatter with respect to zero

residuals. The other correlations based on some new

parameters (IGC-parameters [1]) were lacking in simplicity

and were not always evaluatable easily. It was also found

that the T41J temperature correlation was giving an exces-

sively high value for the reference temperature estimate of

a highly irradiated steel as compared to that based on the

shift procedure applied to the reference temperature esti-

mate of the unirradiated material.

The present paper is in a way a sequel to the paper cited

at [1] and examines the aspects discussed in the previous

paragraph with a view to get an estimate of the reference

temperature, T0, conforming to the triple objectives of

simplicity, consistency (no excessive scatter or erratic

behavior with respect to zero-residuals) and assured (but

not excessive) conservatism where as the aim in [1] was

least conservatism as possible. These objectives are com-

mensurate with the observations in [3], where Nevasmaa

and Wallin have given a comprehensive review of corre-

lations available at the time of their report and have pointed

out the need for verifying, augmenting and updating the

correlations for newer steels, product forms and embrit-

tlement conditions. They have also stated that the tem-

perature based correlations seem to be the most successful

for predicting the reference temperature.

To realize the above objectives, the data for essentially

the same (ferritic) steels as listed in [1] with one or two

additional steels and one additional highly irradiated steel

(provided with both Charpy and reference temperature data

unlike the irradiated and unirradiated Maine-Yankee Weld

examined in [1] which had only Charpy data available) are

P. R. Sreenivasan (&)

Metallurgy & Materials Group, Indira Gandhi Centre

for Atomic Research, Kalpakkam 603102, India

e-mail: sreeprs@yahoo.co.in

123

Trans Indian Inst Met (August–October 2011) 64(4–5):385–393

DOI 10.1007/s12666-011-0090-9

reexamined using two recently proposed lower-bound type

correlations [4–6] (not referred in [3]) along with the T41J

and T28J temperature correlations referred above. An

attempt has also been made to develop a multi-parameter

Charpy energy–fracture toughness correlation modelled

after the Schindler formula [1, 7, 8]. These new correla-

tions are analysed keeping in mind the triple objectives of

simplicity, consistency and assured conservatism as stated

above.

2 Methodology

2.1 Direct Charpy Energy (CV) Temperature–T0

Correlations

The correlation developed in [1] based on the T41J tem-

perature was (Eq. T5-2 in Table 5 of [1]):

TQ�41a ¼ �275:28þ 252:19expð0:00463T41JÞðCorrelation coefficient R ¼ 0:9591;

Standard Error of Estimate, SEE ¼ 17:5�C) ð1Þ

where TQ-41a is the reference temperature (T0) estimate

based on Eq. 1. As there is one more correlation discussed

at the end of this section based on the T41J temperature,

the T0 estimate from Eq. 1 carries the subscript ‘a’. It was

also shown in [1] that the direct application of Eq. 1 to

the irradiated Maine-Yankee weld resulted in an

excessively high estimate for the T0 of the irradiated

material as compared to that obtained by applying the

shift procedure to the T0 estimate of the unirradiated

material; i.e., TQ-41a of the irradiated material obtained

from Eq. 1 using the T41J temperature of the irradiated

material was much larger than the value obtained by

applying the DT41J shift (change in the T41J temperature

from the unirradiated to the irradiated condition: i.e., T41J

(irradiated) - T41J (unirradiated); often a multiplication

factor ranging from 1 to 1.5 is applied to the DT41J shift

for calculating the transition temperature shift) procedure

to the TQ41a of the unirradiated material. Similarly, based

on the T28J temperature, the conservative correlation was

given to be Eq. 3a in [1])

TQ�28CON ¼ 1:18T28J þ 12:52 ð2Þ

where TQ-28CON is the conservative reference temperature

(T0) estimate based on Eq. 2. Equation 2 sometimes

exhibited excessive scatter and was not always the most

conservative.

Now it is proposed to examine the conservative

expression based on the T41J temperature given by Sattari-

Far and Wallin [9] (Eq. 4a in [1]) given below:

T0�1r ¼ T41J � 1 ð3Þ

Without loss of generality this can be stated as:

TQ41b ¼ T41J ð4Þ

and this line is shown Fig. 1 for a set of data from [9]

(Fig. 8.4 data points for unirradiated and irradiated steels

digitized) and [1] (Table 1 data) and is obviously conser-

vative as it describes a sort of upper-bound and will be

much more conservative than a mean-fit correlation.

Moreover, Fig. 1 shows that the data for some irradiated

steels also are described by Eq. 4 conservatively. So Eq. 4

is satisfactory from the points of view of assured conser-

vatism and simplicity. Figure 2 shows the residuals for the

TQ41a and TQ41b estimates for the unirradiated steels shown

in Fig. 1. It is obvious that the TQ41a estimates show wider

scatter and some high nonconservative values while the

estimates based on TQ41b show consistent scatter and

assured conservatism, with only a few nonconservative

values (i.e., positive residuals) which are less than 15�C,

but mostly less than 5�C.

2.2 Recent CVN Energy (CV)–KIC Correlations and T0

Estimates

2.2.1 Lower-Bound (LB) Estimate for Upper-Shelf (US)

Fracture Toughness by the MPA Procedure

(MPALB)

In [4], a recent relation between mean Ji and mean JIC has

been derived as given below (Eq. 9.1 in [4]):

Ji ¼ �400 N/mm +

ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi

160000 ðN/mmÞ2 þ 470 ðN/mmÞJIC

q

ð5Þ

By transposing, squaring and rearranging, Eq. 5 can be

put in the following form:

T41J / 0C

-150 -100 -50 0 50 100 150

T0

/ 0 C

-200

-150

-100

-50

0

50

100

150

200Data from Table 1 of [1]

Uirradiated Data from Fig. 8.4 [9]

Irradiated Data from Fig. 8.4 [9]

KS-01-Weld-Unirradiated [12]

KS-01-Weld-Irradiated [12]TQ41b = T41J

Fig. 1 Conservatism of the TQ41b = T41J correlation

386 Trans Indian Inst Met (August–October 2011) 64(4–5):385–393

123

JIC ¼ðJiðN=mmÞ þ 400ðN=mmÞÞ2 � 160; 000ðN=mmÞ

470 ðN/mmÞð6Þ

Thus Eq. 6 converts initiation J, Ji to JIC, the value

of J determined using the blunting line procedure or

corresponding to a certain amount of crack growth

(usually, 0.2 mm) and is related to the LEFM KIC

through the following relation:

KIC ¼ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi

E

ð1� t2Þ JIC

s

ð7Þ

where E is the Young’s modulus and t is the Poisson’s ratio.

In [4], Fig. 9.3 depicts the relationship between CV and Ji

based on Ref. 4 data and data from MPA, Stuttgart and also

gives the mean fit line and 2r (standard deviation) lower and

upper bound lines, which actually bound almost all the data

points. The digitized data from the three lines in Fig. 9.3 of

Table 1 Basic steels and their properties (Source reference of A517F steel indicated in square brackets; all other steels are the same as in [1])

Steel rys-RT

(MPa)

T0

(�C)

TQ41b =

T41J (�C)

T28J

(�C)

TQSLF =

TK100SLFLB (�C)

TQWLB =

TK100WLB (�C)

TQMPA =

TK100MPALB (�C)

TQ-M2

(�C)

HSLA-LT 445 -100 -59 -67.5 -85 -59.5 -51 -72

HSLA-TL 445 -84 -33.5 -48.5 -61 -32 -2 -47.3

DuplxSS-BM 483 -143 -121 -123 -124.6 -124 -90.5 -122.8

DuplxSS-WM 596 -101 -53.5 -66 -47.5 -54.5 -44 -50.5

JAERI-JRQ 488 -66 -25 -37 -26 -19 -1.5 -25.5

JAERI-StA 469 -67 -42 -54 -60 -41.5 -18.5 -51

JAERI-StB 462 -97 -61 -68 -73 -60.5 -48 -67

(403Fig 10) 675 -28 17 -3 -15.4 18 62 0.8

(A217Fig 11) 422 -89 -32 -48 -72.5 -28 -11.5 -52.3

(A470) 611 93 92 71 109 102 136 100.5

(A471) 911 -19 29 10.3 -51 36 108 -11

(72 W) 500 -54 -27 -41 -35 -25 1 -31

(DuplxSS-Holz) 450 -120 -83 -98 -100.5 -85 -58.5 -91.8

V1233St 551.6 57 41 28 46 42 60 43.5

(124K406) 637 69 56.5 39 48.5 62 100 52.5

2618 Steel 630 11 30 10 33.5 31 70 31.8

916381Steel 590 -15 13.5 0 21 15 38 17.3

X70-T-Steel 531 -131 -107 -114 -107 -109 -96 -107

X70-S-Steel 561 -125 -98 -107 -92 -100 -85.5 -95

Steel5(AD) 414 -131.2 -109 -107 -126.5 -110 -104 -117.8

Steel5(SA) 579 -88.2 -60 -24 -55 -62.5 -48 -57.5

Steel7(AD) 726 -132.8 -96.5 -116 -106 -104 -74 -101.3

Steel7(SA) 896 -92 -43 -93 -73.5 -51.5 -32 -58.3

A1 434 -74 -53 -61 -76 -53 -36.5 -64.5

A2 465 -86 -71 -79 -86 -71 -53 -78.5

A3 479 -89 -72.5 -79 -81 -74 60 -76.8

BARC-JRQ 524 -76 -32.8 -43 -33 -32 -9.5 -32.9

BARC-JPG 552 -100 -79 -80 -18 -76 -69.5 -48.5

(Steel-3178) 768 -79.5 -45 -102 -84 -54 -9 -64.5

(Steel-9241) 860 -109.4 -56 -81 -102 -62 -87 -79

(Steel-9980) 1,050 -18 42 12 -24 36 95 9

124J357 550 12 7.5 -14 9 8 32 8.3

(A517F [13]) 756 -64 -63 -90 -76 -71 -23 -69.5

(A36-Steel) 250 -35 18 10 -8.8 21.4 34 4.6

BS4360-50D [14] 327 -105 -62.5 -75.4 -96.5 -60.5 -38.5 -79.5

Trans Indian Inst Met (August–October 2011) 64(4–5):385–393 387

123

[4] are replotted and shown in Fig. 3. The Ji values

corresponding to the LB line (i.e., MF - 2r) in Fig. 3

were converted to JIC using Eq. 6 and a fit made to the

corresponding CV-JIC values to get the following relation:

JIC ¼ �87:8þ 76:6exp(0:0071CVÞ ð8ÞEquation 8 is shown by the dotted line in Fig. 3. Thus

from the CV in the transition region, JIC and KIC can be

calculated using Eqs. 8 and 7. Then the temperature cor-

responding to a KIC = 100 MPaHm, is designated TK100-

MPALB, the subscript indicating the MPALB procedure as

given in the title to this section. Then, TK100-MPALB is

correlated to T0 as described later.

2.2.2 Lower-Bound (LB) Estimate for Upper-Shelf (US)

Fracture Toughness by the Wallin LB (WLB)

Procedure

Recently Wallin [5, 6] has derived a near-lower-bound

correlation for predominantly ductile fracture (especially

applicable to Charpy US region) in the temperature region

-100 to 300�C. In fact, this new correlation gives not only

the initiation J-value, but also the J–Da tearing resistance

curve (J–R curve) as a function of CV values in the US as a

function of temperature. The correlations are as given

below:

J ¼ J1 mmDam (kJ m�2; mm) ð9Þ

where

J1 mm ¼ 0:53 C1:28V�US exp � T � 20

400

� �

ðkJ m�2; J; �CÞ

ð10Þ

and

m ¼ 0:133 C0:256V�US exp � T � 20

2; 000

� �

� rys�RT

4664

þ 0:03 ðJ; �C, MPaÞ ð11Þ

By putting Da = 0.2 mm in Eq. 9, one can determine

a J0.2 value, which when plugged into Eq. 7 can give a

KIC value. As in the previous section, from the CV values

in the transition region corresponding KIC values are

determined and the temperature corresponding to a

KIC = 100 MPaHm is designated TK100-WLB, the

subscript indicating the WLB procedure. Then, TK100-

WLB is correlated to T0 as described later. For applying

the above procedure, actual yield stress–temperature

relation has been used in the present paper. In the

absence of actual yield stress, yield stress scaled from a

general relation as described in [1, 5, 6] can also be

used.

2.3 A New Charpy–Fracture Toughness Correlation:

Schindler-Like-Fit (SLF) Procedure [1, 7, 8]

Schindler relation (Eq. 12) [1, 7, 8] for computing dynamic

initiation J, Jd is:

Jd ¼7:33 � n � CV � 10�3

1� 1:47 � CV

rfd

� � ð12Þ

where CV is the total CVN energy, i.e., the impact energy

in J, Jd is in J mm-2, n is the power-law exponent (see

Eq. 13 below) and rfd is the dynamic flow stress–mean of

the dynamic yield and maximum stresses [1]; the work-

hardening exponent (n) values are obtained from [1, 10]:

n ¼ 10�ðlog ry�log 60Þ ð13Þ

where ry = ryd is in MPa. In the following, modelled after

Eq. 12, the KIC values corresponding to CV = 30–70 J

(approximate range where KIC = 100 MPaHm is likely to

occur) for some selected steels are fitted to the following

relation:

T0 / 0C

-200 -150 -100 -50 0 50 100 150

T0(

mea

sure

d) -

T0(

estim

ated

)

-120

-100

-80

-60

-40

-20

0

20

40

60

TQ41a - RESIDUALS

TQ41b-RESIDUALS

Fig. 2 Residuals of TQ41a and TQ41b estimates for the unirradiated

data in Fig. 1 compared

CV / J

0 50 100 150 200 250 300

J i or

J IC /

N.m

m-1

0

100

200

300

400

500

Ji = -120.25 + 131.71exp(0.0046CV )

Ji = -71.18 + 63.62exp(0.0054CV )

Ji = -158.22 + 192.31exp(0.0044CV )

MF - 2σ

MF + 2σ

Mean Fit - MF

JIC = -87.8 + 76.6exp(0.0071CV )

Fig. 3 MPA–Stuttgart CV–Ji and CV–JIC relation [4]

388 Trans Indian Inst Met (August–October 2011) 64(4–5):385–393

123

KIC ¼A � n � CV

1� B � CV

rys

� � ð14Þ

where the work hardening exponent n is determined from

Eq. 13 using the static yield stress (rys) at the particular

temperature and A and B are fit constants. Thus when A

and B values for a particular steel are known, KIC values in

the transition region can be calculated by applying Eq. 14

and the temperature corresponding to a KIC = 100

MPaHm is determined as TK100-SLF, the SLF in the sub-

script indicating SLF. TK100-SLF is correlated to T0 as

described later.

3 Materials and Data

The ASTM E-1921 reference temperature, T0, room tem-

perature yield stress and other temperature data for 35

steels used for generating the various correlations discussed

in Sect. 2 are given in Table 1. Most of the steels are

essentially the same as given in Tables 1 or 3 of [1]. Only

for those steels which are not presented in [1], the source

references are indicated in the present Table 1. The steels

covered (plane carbon ferrite-pearlite steels, high alloyed

AISI 403 (12Cr) martensitic stainless steels (SSs), duplex

SSs, weld, etc.) range in yield strength from *275 to more

than 1,000 MPa. Table 3 lists the steels (essentially the

same steels as listed in Table 3 of [1] with duplications

from Table 1 removed) used for prediction of reference

temperature from the various correlation models developed

using data in Table 1 along with their properties. The data

in the present paper should be treated as updated one

compared to those in [1].

4 Results and Discussion

4.1 Direct Charpy Energy (CV) Temperature–T0

Correlations and Recent CVN Energy (CV)–KIC

Correlations and T0 Estimates

Items under Sects. 2.1 and 2.2 are discussed here under one

heading. As was discussed in Sect. 2.1, values of

TQ41b = T41J are listed in Table 1 along with TK100-WLB

and TK100-MPALB. One striking feature that emerges in

comparing the values of TQ41b (= T41J) and TK100-WLB in

Table 1 is that they appear to differ only marginally. Hence

for all practical purposes, in this context, TK100-WLB can be

taken as equal to TQ41b (= T41J); hence, the estimate of

reference temperature based on the WLB procedure,

TQWLB can be taken as equal to TK100-WLB (= TQ41b) as

TQ41b seems to be the most conservative estimate. This is

indicated so in Table 1. Moreover, estimating the TQ41b

values is much simpler compared to the multi-step calcu-

lations involved in calculating the WLB procedure based

values.

Figure 4 shows a plot of various TQX estimates against

T0. Since, as discussed in the previous paragraph, TQWLB is

taken as equal to TQ41b, only TQ41b is shown and it seems to

be the most conservative. Disposition of the points in

Fig. 4 with respect to the 1:1 line (i.e., TQX = T0) justifies

taking TQX = TK100-X as the conservative estimate of ref-

erence temperature; for example, TQMPA = TK100-MPALB.

This is indicated in Table 1 also. The other TQX estimates

shown in Fig. 4 will be discussed in the next Section.

Overall, TQMPA proves to be consistently ultraconservative

compared to other estimates. This much conservatism is

not warranted if other lesser conservative estimates are

more reliable and consistent.

4.2 T0 Estimates from the Schindler-Like-Fit

Procedure

For implementing the SLF procedure as discussed in Sect.

2.3, the data for the 12 steels, whose names have been

enclosed in parentheses in Table 1, were used. Full valid

KIC data over the whole transition region was available for

these steels, while for most of the other steels only the

reference temperature data were available. The fit constants

A and B in Eq. 14 above obtained for the 12 steels are as

shown in Fig. 5 as a function of room temperature yield

stress. The individual points have been joined by linear

interpolation to enable easy determination of values of A

and B for other steels with different RT-YS values. As can

be seen from Fig. 5, A has positive values while B has

negative values; A and B show a somewhat mirror-image

like behaviour. Such discontinuous variation may be

unpalatable to most. However, by assuming that such a

-200 -100 0 100

T0

/ 0 C

-200

-150

-100

-50

0

50

100

150

TQX = TQ41b = T41J

TQX =TQSLF = TK100-SLFLB

TQX = TQMPA = TK100-MPALB

TQX = TQM2

TQX / 0C

TQX = T0 LINE

Fig. 4 Various TQ estimates compared with T0

Trans Indian Inst Met (August–October 2011) 64(4–5):385–393 389

123

variation is acceptable, let us see how the prediction works

for other steels. For two of the steels—A517F and Dup-

lxSS-Holz—whose data were used for generating the fit

constants A and B, the predictions of KIC from the fit

(Eq. 14) are compared with the actual values (in the

Charpy energy range of 30–70 J) in Fig. 6. Though, in the

Charpy energy range of 30–70 J, for the A517F steel

the fracture toughness spans the 100 MPaHm, for the

DuplxSS-Holz, an extrapolation to lower values is required

to get the 100 MPaHm value. For small extrapolations,

that may be permissible; but when large extrapolations are

needed, those have been avoided. For ease of extrapolation,

the linear interpolated data have been tabulated and

presented in Table 2. As can be seen from Fig. 4, for a

conservative estimation of reference temperature, it is

reasonable to put TQSLF = TK100-SLF and this is indicated in

Table 1 also.

4.3 Final Comparison and Evaluation: Mean-2

Procedure (M2P)

For the steels listed in Table 1 and Fig. 7 compares the

residuals (defined as the difference between the measured

and the estimated value) for the three T0 estimates, namely,

TQ41b, TQMPA and TQSLF along with those for TQ41a (Eq. 1)

and the TQ-28CON (Eq. 2). From the definition, negative

residuals indicate conservative estimates, that is, estimates

larger than the measured values. Obviously, TQMPA is

consistently the most conservative. TQ41a and TQ-28CON are

more inconsistent and many times do not offer assured

conservatism. Though more inconsistent than TQ41b, TQSLF

is acceptably conservative but for one or two rogue steels

(as discussed in [1]); even in those cases, the nonconser-

vatism is not more than 20�C. So, for the larger conser-

vative prediction of reference temperature, take the most

conservative (i.e., the most positive) of the two values:

TQ41b and TQSLF; but for a value with reduced, but assured,

conservatism, take the mean of the two. This mean-2 value

is designated—TQ-M2. The residuals of the TQ-M2 shown in

Fig. 7 justifies the points discussed in this paragraph. The

two estimates seem to have mutually compensating ten-

dencies and the mean-value delivers a result satisfying the

starting objectives of simplicity, consistency and assured

conservatism. Moreover, as will be shown in the next

Section, they are applicable to highly irradiation embrittled

conditions also.

4.4 TQ-M2 Predictions for Some New Steels

Some new steels given in Table 3 (same steels as given in

Table 3 of [1], but with duplications from Table 1

removed) have been evaluated by the M2P. One new

highly irradiation embrittled steel from [11] with both

Charpy and reference temperature data (including yield

stress data variation with temperature for the irradiated

steel also) has also been added. As in [1], the other steels

include the five steels tested at IGCAR for which only

CVN data are available. The TQ-M2 values are also given in

Table 3. For those steels for which measured T0 values are

available in Table 3, the respective TQ-M2 values are

compared against T0 in Fig. 8. The TQ-M2 values them-

selves seem to be conservative. For the five IGCAR steels

(91Wld-IGC—a 9Cr1Mo weld, 403SS-IGC—a 12Cr mar-

tensitic SS, 91BM-IGC—a normalized and tempered

9Cr1Mo martensitic steel, 21IGC—a 2.25Cr1Mo steel and

A-48P2-IGC—an A48P2 Type steel), the estimates of T0

values obtained by the M2P (7.5, 22.3, -79.3, -30 and

-75.8�C, respectively) seem to be reasonably conservative

RT-YS/MPa

200 400 600 800 1000 1200

A o

r B

-100

-50

0

50

100

150A - Interpolated LineB - Interpolated LineA - Raw DataB-Raw Data

Fig. 5 Interpolated line from the data points for A and B for 12 steels

as a function of RT-YS

Temperature/ 0C

-110 -100 -90 -80 -70 -60 -50 -40 -30

KIC

/ M

Pa.

m-0

.5

60

80

100

120

140

160

180

A517F Steel - Measured DataA517F Steel - Predicted or Fit DataDuplxSS-Holz: Measured DataDuplxSS-Holz: Predicted or Fit Data

Fig. 6 Comparison of experimental KIC data with those from the SLF

for two steels in the 30–70 J Charpy energy range

390 Trans Indian Inst Met (August–October 2011) 64(4–5):385–393

123

estimates. From the comparison of TQ-M2 vs. TQ41b shown

in Fig. 8, TQ41b seems to be more conservative than TQSLF

for most of the Table 3 steels.

Another point to note in Table 3 is that the values of

TQWLB for the unirradiated steels is almost the same as

their TQ41b values as was the case for the Table 1 steels.

However, for the two irradiated steels, M-YWld-IRR and

KS-01-Wld-Irr, the TQWLB estimates show very high values

compared to the estimates based on TQ41b. For the

Maine-Yankee Reactor Weld (M-YWld-UNIRR and

M-YWld-IRR indicating virgin and irradiated conditions,

respectively) (Table 3), the T41J values shift from -36 to

182�C, giving a shift of 218�C (= DT41J), while the TQ-M2

values shift from -48 to 162.5�C, giving a shift of 210�C

(= DT0); thus the two shifts seem to be comparable. As is

evident from Fig. 1, the conservatism of the TQ41b for the

irradiated steels is not as much as that for unirradiated

steels. Hence in the present case, it may be prudent to take

the more conservative estimate based on TQ41b and its shift,

if necessary with an additional multiplication factor applied

to the DT41J shift, i.e., DT0 = 1.28DT41J as is suggested by

Brumovsky et al. [12].

For the KS-01-Wld [11] in Table 3, actual T0 shifts from

-24 to 136�C on irradiation (i.e., DT0 = 160�C) whereas

TQ41b (= T41J) shifts from -9 to 159�C (i.e., DT41J = 168�C)

and TQ-M2 values shift from 0 to 133�C, giving a shift of

133�C, indicating the acceptably conservative nature of the

TQ41b based estimates, though the TQ-M2 based values are not

much off the mark—much conservative for the unirradiated

steel and only 3�C nonconservative for the irradiated steel.

Table 2 Variation of the constants A and B in the SLF procedure for estimating KIC

RT-YS/MPa A B RT-YS/MPa A B RT-YS/MPa A B

250.500 99.207 -39.210 521.517 45.548 -12.915 792.534 91.086 -21.006

264.051 97.023 -36.862 535.068 41.223 -10.963 806.085 100.817 -25.609

277.602 94.839 -34.514 548.619 36.897 -9.012 819.636 110.549 -30.211

291.153 92.655 -32.167 562.169 32.572 -7.060 833.186 120.281 -34.814

304.703 90.471 -29.819 575.720 28.247 -5.109 846.737 130.012 -39.416

318.254 88.287 -27.471 589.271 23.922 -3.157 860.288 139.459 -43.834

331.805 86.103 -25.123 602.822 19.597 -1.206 873.839 135.814 -39.746

345.356 83.919 -22.775 616.373 20.191 -1.600 887.390 132.168 -35.658

358.907 81.734 -20.427 629.924 28.271 -5.563 900.941 128.523 -31.569

372.458 79.550 -18.079 643.475 41.605 -8.693 914.492 125.929 -28.155

386.008 77.366 -15.731 657.025 60.679 -10.914 928.042 126.366 -26.680

399.559 75.182 -13.383 670.576 79.754 -13.135 941.593 126.803 -25.206

413.110 72.998 -11.035 684.127 81.581 -13.010 955.144 127.240 -23.731

426.661 73.349 -11.666 697.678 75.050 -11.748 968.695 127.677 -22.257

440.212 78.536 -17.977 711.229 68.518 -10.486 982.246 128.115 -20.782

453.763 80.035 -22.046 724.780 61.986 -9.225 995.797 128.552 -19.308

467.314 71.940 -20.278 738.331 55.455 -7.963 1009.347 128.989 -17.833

480.864 63.846 -18.510 751.881 48.923 -6.701 1022.898 129.426 -16.359

494.415 55.751 -16.742 765.432 64.333 -10.514 1036.449 129.863 -14.884

507.966 49.873 -14.866 778.983 81.354 -16.404 1050.000 130.300 -13.410

STEEL

HS

LA-L

TH

SLA

-TL

Dup

lxS

S-B

MD

uplx

SS

-WM

JAE

RI-

JRQ

JAE

RI-

StA

JAE

RI-

StB

403F

ig10

A21

7Fig

11A

470

A47

172

WD

uplx

SS

-Hol

zV

1233

St

124K

406

2618

Ste

el91

6381

Ste

elX

70-T

-Ste

elX

70-S

-Ste

elS

teel

5(A

D)

Ste

el5(

SA

)S

teel

7(A

D)

Ste

el7(

SA

)A

1A

2A

3B

AR

C-J

RQ

BA

RC

-JP

GS

teel

-317

8S

teel

-924

1S

teel

-998

012

4J35

7A

517F

-Ste

elA

36-S

teel

BS

4360

T0(

mea

sure

d) -

TQ

X(e

stim

ate)

/ 0 C

-100

-80

-60

-40

-20

0

20

40

-100

-80

-60

-40

-20

0

20

40

TQX = TQ41b

TQX = TQMPA

TQX = TQ41a

TQX = TQ28CON

TQX = TQSLF

TQX = TQM2

Fig. 7 Comparison of the residuals for the various estimates of the

reference temperature, T0

Trans Indian Inst Met (August–October 2011) 64(4–5):385–393 391

123

5 Conclusions

1. A mean-value of the two procedure (M2P) has been

proposed for estimation of reference temperature,

T0, from CVN tests alone and has been established

through a correlative approach.

2. The T0 estimate from the M2P is referred as, TQ-M2, and

is obtained as the mean value of the two estimates,

namely, the 41 J CV temperature (T41J) correlation

estimate, TQ41b, and the SLF procedure estimate, TQSLF.

3. Simplicity, consistency and assured conservatism of

the TQM2 has been demonstrated by comparison with

measured T0 values for some new steels. For the most

conservative estimate, it is suggested to take the most

conservative of the two and this, in most cases happens

to be the estimate, TQ41b, and is the same as T41J and

hence very simple to estimate.

4. The new two-parameter SLF procedure for predicting

fracture toughness from CVN energy is promising and

needs further validation and verification.

5. The applicability of the M2P for irradiated steels has

been demonstrated.

Acknowledgments The author acknowledges with thanks the

excellent support and encouragement received from Director, MMG

and Director, IGCAR, Kalpakkam, India.

Table 3 Data on new steels for testing and prediction using the correlations developed from Table 1 data (Source reference for KS-01-Weld

indicated in square brackets)

Steel rys-RT

(MPa)

T0

(�C)

TQ41b = T41J

(�C)

T28J

(�C)

TQSLF =

TK100SLF LB (�C)

TQWLB =

TK100WLB (�C)

TQMPA =

TK100MPALB (�C)

TQ-M2

(�C)

A533BKob 690 -167 -182 -175.4 -179 -145 -171.2

A508CL-A 540 -36 -42 -33 -33 -26 -34.5

A508CL-A0 479 -16 -20 -31 -17 -6.5 -23.5

GTWSA533A070 753 -52 -70 -55 -50 -34 -53.5

A203D-NT 390 -98 -109 -128 -100 -16 -113

403SS-DQT 615 -25 -2.5 -26 9 -13.8

403SS-QT 626 49 67 54 84 58

A508Forge 481 -49 -6 -17 -19 -4 14 -12.5

M-YWld-UNIRR 453 -36 -48 -60 -35.5 -9 -48

M-YWld-IRR 771.4 182 153 143 231 268 162.5

EURO-BM 481 -95 -45.5 -55 -57 -45 -26 -51.3

EURO-WM 605 -75 -25 -35 -12.5 -25 -2 -18.8

Manet-II-UA 669 -18 -67.5 -44 -18 -2 -31

Manet-II-Aged 633 -11 -48.5 -1 -11 12 -6

KS-01-Weld-UIrr [11] 601 -25 -9 -27 9.7 -8 31 0.3

KS-01-Weld-Irr [11] 826 136 159 129 107 185 347 133

IGCAR STEELS

91Wld-IGC 560 8.5 -3 6.4 10 27.3 7.5

403SS-IGC 650 34.5 21.5 10 36.5 59 22.3

91-BM-IGC 512 -79 -90 -79.5 -81 -57 -79.3

21IGC 280 -20.5 -28 -39.4 -18.5 -5.5 -30

A48-P2-IGC 555.5 -76.5 -75 -77 -72 -75.8

TQ-Mi2 / 0C

-200 -150 -100 -50 0 50 100 150 200

T0

(mea

sure

d) o

r T

Q41

b / 0 C

-200

-150

-100

-50

0

50

100

150

200

TQM2 vs T0

TQ-M2 vs TQ41b

Fig. 8 TQ-M2 of the Table 3 steels compared with available T0 or

TQ41b

392 Trans Indian Inst Met (August–October 2011) 64(4–5):385–393

123

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