THE CREEP AND FATIGUE BEHAVIOR OF HAYNES 282 AT

ELEVATED TEMPERATURES

Sara C. Longanbach and Carl J. Boehlert

Michigan State University, Department of Chemical Engineering and Materials Science, East

Lansing, MI 48824

Haynes 282 is a wrought, gamma-prime strengthened nickel-based superalloy intended for use in

high temperature structural applications. In order to investigate processing-microstructure-

property relationships, the microstructure and elevated-temperature creep and fatigue behavior of

Haynes 282 were evaluated after it had been processed using strain-recystrallization

thermomechanical treatments. These treatments included a sequence of 20% cold rolling steps

followed by recrystallization annealing. Microstructural evaluation was performed using

scanning electron microscopy (SEM) and electron backscattered diffraction (EBSD). Figure 1(a)

illustrates the microstructure after the thermomechanical processing treatment. From the

collected EBSD data, the number fraction of certain boundary types was determined. General

high angle boundaries (GHAB) accounted for 38% of the boundaries, while low angle

boundaries (LAB) accounted for 4%. 58% of the boundaries were coincident site lattice

boundaries (CSLB) and it is noted that 47% of the overall boundaries were twins (Σ3). The

majority of the boundaries were categorized as CSLB+LAB, and these have been associated with

enhanced creep resistance for other superalloy systems. The creep and fatigue properties at

elevated temperatures (760°C – 815°C) of this alloy were examined and compared to the results

obtained for two solid solution-strengthened superalloys, nickel-based Haynes 230 and cobalt-

based Udimet 188. Figure 2 compares the creep behavior for the alloys and it is evident that the

Haynes 282 is the most creep resistant. The measured creep exponents (n) (Figure 2) for each of

the alloys suggest that similar creep deformation mechanisms may be active. Figure 3 (a)

illustrates a plot used to calculate the Qapp values for Haynes 282 at different stresses. It is

expected that the dominant secondary creep mechanism was dislocation climb and this will be

evaluated using TEM of the deformed samples. The strain-life history of the fatigue experiments

revealed that creep contributed to the total strain accumulated in the samples; see Figure 3 (b).

The Young’s modulus decreased during fatigue testing indicating that damage likely occurred

during these experiments. The creep-fatigue synergisms and deformation mechanisms will be

evaluated using electron microscopy.

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(a) (b)

Figure 2. (a) Creep strain versus time plot (T = 760°C and σ = 100 MPa) and (b) minimum creep rate

versus stress plot to determine the creep exponent value (n) at T = 760°C for Haynes 230, Haynes 282

and Udimet 188.

0

0.5

1

1.5

2

2.5

0 50 100 150 200 250 300 350

H230H282UD188

Cre

ep

Str

ain

[%

]

Time [hr]

T = 760ºC

σσσσ = 100 MPa

10-10

10-9

10-8

10-7

10-6

100 1000

H230 - n = 5.9H282 - n = 6.2UD 188 - n = 6.6

Min

imu

m C

reep

Rate

[s

-1]

Stress [MPa]

T = 760ºC

(a) (b)

Figure 1. (a) BSE SEM image of Haynes 282 microstructure before the age-hardening heat

treatment and (b) an EBSD image quality map highlighting the distribution of grain boundary

misorientations (red (2°-5°) and green (5°-15°) = LAB, blue = GHAB, purple = CSLB

(excluding Σ3) and yellow = Σ3).

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(a) (b)

Figure 3. (a) ln(minimum creep rate) versus 10000/T plot used to caluculate Qapp value for

Haynes 282 at three different creep stresses and (b) strain versus time plot during a load-

controlled fatigue experiment (R = 0.1) at a maximum applied stress of 175 MPa at T =

815°C. The strain/time behavior resembled that for the creep experiment at σ = 175 MPa and

T = 815°C which is overlaid on the plot.

0

1

2

3

4

5

6

7

8

0 50 100 150 200

H282 - Creep TestH282 - Fatigue Test

To

tal S

tra

in [

%]

Time [hr]

σσσσmax

= 175 MPa

T = 815ºC

-23

-22

-21

-20

-19

-18

-17

-16

-15

9.1 9.2 9.3 9.4 9.5 9.6 9.7

H282 - σσσσ = 100MPa - Qapp

= 701 kJ/mol

H282 - σ σ σ σ = 125MPa - Qapp

= 755 kJ/mol

H282 - σσσσ = 150MPa - Qapp

= 725 kJ/mol

ln(M

inim

um

Cre

ep

Ra

te)

10000/T [K-1

]

760ºC790ºC815ºC

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