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工學博士 學位論文

저 망간 쌍정유기소성강의 응력 변형률 - 거동에 미치는 변형률속도의 영향

Effect of Strain Rate on Stress-Strain Behavior

of Lean Manganese TWinning Induced Plasticity (TWIP) Steels

指導敎授 崔 日 東

2013 年 02 月

韓國海洋大學敎 大學院

材料工學科

宋 炳 煥

工學博士 學位論文

저 망간 쌍정유기소성강의 응력 변형률 - 거동에 미치는 변형률속도의 영향

Effect of Strain Rate on Stress-Strain Behavior

of Lean Manganese TWinning Induced Plasticity (TWIP) Steels

指導敎授 崔 日 東

2013 年 02 月

韓國海洋大學敎 大學院

材料工學科

宋 炳 煥

- 1 -

을 의 으로 함.

本 論文 宋炳煥 工學博士 學位論文 認准

委員長 工學博士 李 成 烈 ㊞ 委 員 工學博士 文 慶 萬 ㊞ 委 員 工學博士 崔 日 東 ㊞ 委 員 工學博士 李 柄 雨 ㊞ 委 員 工學博士 李 泰 昊 ㊞

2012 年 12 月 05 日

韓國海洋大學敎 大學院

- 2 -

- 3 -

- 4 -

- 5 -

- 6 -

- 7 -

- 8 -

- 9 -

- 11 -

 ×

 



 ×

- 12 -

- 1 -





 ^′

_

_{ }  → ^′

_{ }

- 2 -

 

 ≤ ≤

≤ ≤ 



 ^′





  ^′

- 3 -



- 4 -

×

- 5 -

- 6 -

_ → _ _ → →

_

_

- 7 -

_ _

_ 





^



^



^





^{    }

^

_ 





^



^



^





^{     }

^

_ 





^



^



^





^{    }

^

_→ _ _ _^ _^ _^ _^ _^ _^

_ _ _ _ 

^

_ _ 

^

_→ _ _



 __→



 _{}_{ }



_

→ →



- 8 -

- 9 -

- 10 -









- 11 -

 → ^′



 → ^′

 → ^′

- 12 -

- 13 -

- 14 -

- 15 -

×

- 16 -

- 17 -

- 18 -

- 19 -

- 20 -



- 21 -

- 22 -

×

×

- 23 -

- 24 -

- 25 -

- 26 -

- 27 -

- 28 -

- 29 -

- 30 -

×

- 31 -

 → ′



^→

   ∆^{→ } ^

_



^→

^

- 32 -

′

_

_{}

_{}

^′ 

- 33 -

- 34 -

- 35 -

40 45 50 55 60 65 70 75 80 85 90 95 0

200 400 600 800 1000 1200 1400 1600

Intensity (cps)

(311)g (220)g

(200)g (111)g

2Theta(deg)

18Mn raw

40 45 50 55 60 65 70 75 80 85 90 95 0

50 100 150 200 250 300 350

2Theta(deg)

(311)g

(220)g (200)g

(111)g

Intensity (cps)

12Mn raw

- 36 -

- 37 -

×

 ^{ }





× × × ^{ }

× × × ^{ }

- 38 -



〈〉

_{}

_{} 







_{}

- 39 -

_ _ ^

_^{  }

_ _ _  ∞

_^{  }



_

_ 

 ^

_^{  }



 ^

_^{  }

_

_

- 40 -

- 41 -

 →  ^′

- 42 -

- 43 -

- 44 -

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0

200 400 600 800 1000 1200

Eng. Strain

10^-1s^-1 10^-2s^-1 10^-3s^-1 10^-4s^-1

Eng. Stress (MPa)

(a) 18Mn

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0

200 400 600 800 1000 1200

Eng. Stress (MPa)

Eng. Strain

10^-1s^-1 10^-2s^-1 10^-3s^-1 10^-4s^-1

(b) 12Mn

- 45 -

0.3 0.4 0.5 0.6 0.7

800 850 900 950 1000 1050

Eng. Strain

10^-1s^-1 10^-2s^-1 10^-3s^-1 10^-4s^-1

Eng. Stress (MPa)

(a) 18Mn

0.1 0.2 0.3 0.4 0.5 0.6 700

800 900 1000 1100 1200

Eng. Stress (MPa)

Eng. Strain

10^-1s^-1 10^-2s^-1 10^-3s^-1 10^-4s^-1

(b) 12Mn

- 46 -

40 45 50 55 60 65 70 75 80 85 90 95 0

100 200 300 400 500

2Theta(deg)

Intensity (cps)

18Mn 10-1s-1

(311)g (220)g

(200)g (111)g

40 50 60 70 80 90

0 100 200 300 400

2Theta(deg)

Intensity (cps)

18Mn 10- 2s-1

(311)g (220)g

(200)g (111)g

40 45 50 55 60 65 70 75 80 85 90 95 0

50 100 150 200 250 300 350 400

2Theta(deg)

Intensity (cps)

18Mn 10^-3s-1

(311)g (220)g

(200)g (111)g

40 45 50 55 60 65 70 75 80 85 90 95 0

50 100 150 200 250 300 350

Intensity (cps)

2Theta(deg)

18Mn 10^-4s-1

(311)g (220)g

(200)g (111)g

40 45 50 55 60 65 70 75 80 85 90 95 0

20 40 60 80 100 120 140 160 180

2Theta(deg)

Intensity (cps)

12M n 10-2s-1

(220)g (200)g

(111)g

(220)g

40 45 50 55 60 65 70 75 80 85 90 95 0

20 40 60 80 100 120 140 160

2Theta(deg)

Intensity (cps)

12Mn 10-1 s-1

(220)g (200)g

(111)g

(311)g

40 45 50 55 60 65 70 75 80 85 90 95 0

20 40 60 80 100 120 140 160

2Theta(deg)

Intensity (cps)

12Mn 10-3 s-1 (220)g

(200)g (111)g

(311)g

40 45 50 55 60 65 70 75 80 85 90 95 0

20 40 60 80 100 120 140 160 180

2Theta(deg)

Intensity (cps)

12Mn 10-4s-1

(311)g (220)g

(200)g (111)g

- 47 -

- 48 -

- 49 -

- 50 -

- 51 -

- 52 -

- 53 -

10^-4 10^-3 10^-2 10^-1 500

600 700 800 900 1000 1100 1200

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

Strain Rate (s^-1)

Eng. UTS (MPa) UTS Failure Elongation

e_f

(a) 18Mn

10^-4 10^-3 10^-2 10^-1 500

600 700 800 900 1000 1100 1200

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

Eng. UTS (MPa)

Strain Rate (s^-1)

UTS

Failure Elongation

e_f

(b) 12Mn

- 54 -

10^-4 10^-3 10^-2 10^-1 10⁰ 600

700 800 900 1000 1100 1200

1300 e

0.10 0.20 0.30 0.40 0.50

Strain Rate(s^-1)

Flow Stress (MPa) ^{(a) 18Mn}

10^-4 10^-3 10^-2 10^-1 10⁰ 600

700 800 900 1000 1100 1200 1300

(b) 12Mn

Strain Rate(s^-1)

Flow Stress (MPa)

e 0.10 0.20 0.30 0.40 0.50

- 55 -

- 56 -

- 57 -

- 58 -

- 59 -

- 60 -

- 61 -

- 62 -

0 4 8 12 16 20 24 28 32 36 40 44 0

10 20 30 40 50 60 70 80 90 100

Eng. Strain(%) Strain Rate

18Mn 10^-4s^-1 18Mn 10^-1s^-1

Twinned Grain Fraction (%)

0 4 8 12 16 20 24 28 32 36 40 44 400

500 600 700 800 900 1000

Strain Rate 18Mn 10^-4s^-1 18Mn 10^-1s^-1

Stress (MPa)

Eng. Strain(%)

- 63 -

- 64 -

- 65 -

- 66 -

0 4 8 12 16 20 24 28 32 36 0

10 20 30 40 50 60 70 80 90 100

Twinned Grain Fraction (%)

Eng. Strain(%)

Strain Rate 12Mn 10^-4s^-1 12Mn 10^-1s^-1

0 4 8 12 16 20 24 28 32 36 400

500 600 700 800 900 1000

Stress (MPa)

Eng. Strain(%) Strain Rate

12Mn 10^-4s^-1 12Mn 10^-1s^-1

- 67 -

- 68 -

0 10 20 30 40 50 60 70 80 90 100 500

600 700 800 900 1000

Strain Rate 18Mn 10-4s-1 18Mn 10-1s-1 12Mn 10-4s-1 12Mn 10-1s-1

Stress (MPa)

Twinned Grain Fraction (%)

- 69 -

 ^







 





- 70 -



- 71 -

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.0

0.1 0.2 0.3

0.4 (a) 18Mn ₁₀^-4_s^-1

10^-3s^-1 10^-2s^-1 10^-1s^-1

Eng. Strain

Strain Hardening Exponent(n)

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.0

0.1 0.2 0.3

0.4 (b) 12Mn

Eng. Strain

Strain Hardening Exponent(n)

10^-4s^-1 10^-3s^-1 10^-2s^-1 10^-1s^-1

- 72 -

- 73 -

- 74 - 4%

20%

4%

0.0 0.1 0.2 0.3 0.4 0.5

0.0 0.1 0.2 0.3 0.4

S tra in H ar de ni ng E xp on en t(n )

Eng. Strain

Strain Rate : 18Mn 10^-4/s 12Mn 10^-4/s 20%

40%

30%

- 75 -

×

×

×

×

- 76 -

- 77 -

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0

200 400 600 800 1000 1200

1400 (a) 18Mn

10⁰s^-1 10¹s^-1 10²s^-1 2x10²s^-1

Eng. Stress (MPa)

Eng. Strain

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0

200 400 600 800 1000 1200 1400

10⁰s^-1 10¹s^-1 10²s^-1 3x10²s^-1

(b) 12Mn

Eng. Stress (MPa)

Eng. Strain

- 78 -

10^-4 10^-3 10^-2 10^-1 10⁰ 10¹ 10² 600

700 800 900 1000 1100 1200 1300 1400

Strain Rate(s^-1) 18Mn

12Mn

Eng. UTS (MPa)

10^-4 10^-3 10^-2 10^-1 10⁰ 10¹ 10² 0.0

0.1 0.2 0.3 0.4 0.5 0.6 0.7

18Mn 12Mn

Strain Rate(s^-1)

e f (avg)

- 79 -

- 80 -

- 81 -

  _ 

∙

_

- 82 -









  



 

  

 

  _ 

∙∙  



- 83 -

- 84 -

- 85 -

0 2 4 6 8 10 12 14

0 10 20 30 40 50 60 70 80 90 100

Eng. Strain(%)

Strain Rate 18Mn 10¹s^-1 18Mn 10²s^-1

Twinned Grain Fraction (%)

0 2 4 6 8 10 12 14

400 500 600 700 800 900 1000

Strain Rate 18Mn 10¹s^-1 18Mn 10²s^-1

Stress (MPa)

Eng. Strain(%)

- 86 -

- 87 -

- 88 -

0 4 8 12 16 20 24 28 32 36 0

10 20 30 40 50 60 70 80 90 100

Strain Rate 12Mn 10¹s^-1 12Mn 10²s^-1

Twinned Grain Fraction (%)

Eng. Strain(%)

0 4 8 12 16 20 24 28 32 36 400

500 600 700 800 900 1000

Stress (MPa)

Strain Rate 12Mn 10¹s^-1 12Mn 10²s^-1 Eng. Strain(%)

- 89 -

0 10 20 30 40 50 60 70 80 90 100 500

600 700 800 900 1000

Strain Rate 18Mn 10¹s^-1 18Mn 10²s^-1 12Mn 10¹s^-1 12Mn 10²s^-1

Stress (MPa)

Twinned Grain Fraction (%)

- 90 -

0 10 20 30 40 50 60 70 80 90 100 500

600 700 800 900 1000 1100

Strain Rate 18Mn 10^-4s^-1 18Mn 10^-1s^-1 12Mn 10^-4s^-1 12Mn 10^-1s^-1 18Mn 10¹s^-1 18Mn 10²s^-1 12Mn 10¹s^-1 12Mn 10²s^-1

Stress (MPa)

Twinned Grain Fraction (%)

High strain rate

Quasi-static strain rate

- 91 -

- 92 -

- 93 -

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.0

0.1 0.2 0.3

0.4 ^100s-1

10¹s^-1 10²s^-1 2x10²s^-1

Eng. Strain

Strain Hardening Exponent(n)

(a) 18Mn

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.0

0.1 0.2 0.3

0.4 (b) 12Mn

Eng. Strain

Strain Hardening Exponent(n)

10⁰s^-1 10¹s^-1 10²s^-1 3x10²s^-1

- 94 -

×

 _ ^

_

_

_



- 95 -

 ∆

∆



- 96 -



- 97 -

- 98 -

- 99 -

10^-5 10^-4 10^-3 10^-2 10^-1 10⁰ 10¹ 10² 10³ 200

400 600 800 1000 1200 1400

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

UTS YS

Strain Rate (s^-1)

Strength (MPa)

e_f e_u (a) 18Mn

Elongation

10^-5 10^-4 10^-3 10^-2 10^-1 10⁰ 10¹ 10² 10³ 200

400 600 800 1000 1200 1400

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

Strain Rate (s^-1)

Strength (MPa)

UTS (b) 12Mn YS

Elongation

e_f e_u

- 100 -

0 4 8 12 16 20 24 28 32 36 40 44 0

10 20 30 40 50 60 70 80 90 100

Strain Rate 18Mn 10^-4 s^-1 18Mn 10^-1 s^-1 18Mn 10¹ s^-1 18Mn 10² s^-1 12Mn 10^-4 s^-1 12Mn 10^-1 s^-1 12Mn 10¹ s^-1 12Mn 10² s^-1

Twinned Grain Fraction (%)

Eng. Strain(%)

0 4 8 12 16 20 24 28 32 36 40 44 400

500 600 700 800 900 1000

Strain Rate 18Mn 10^-4s^-1 18Mn 10^-1s^-1 18Mn 10¹s^{- 1} 18Mn 10²s^{- 1} 12Mn 10^-4s^-1 12Mn 10^-1s^-1 12Mn 10¹s^{- 1} 12Mn 10²s^{- 1}

Stress (MPa)

Eng. Strain(%)

- 101 -

18Mn 12Mn

-0.03 -0.02 -0.01 0.00 0.01 0.02 0.03

10^-4s^-1 ~ 10⁰s^-1 10⁰s^-1~

Strain Rate Sensitivity

- 102 -

10^-4 10^-3 10^-2 10^-1 10⁰ 10¹ 10² 10³ 600

700 800 900 1000 1100 1200 1300

Strain Rate (s^-1)

e 0.10 0.20 0.30 0.40 0.50

Flow Stress (MPa)

10^-4 10^-3 10^-2 10^-1 10⁰ 10¹ 10² 10³ 600

700 800 900 1000 1100 1200 1300

Strain Rate(s^-1)

Flow Stress (MPa)

e 0.10 0.20 0.30 0.40 0.50

- 103 -

10 15 20 25 30 35

-0.05 -0.04 -0.03 -0.02 -0.01 0.00 0.01 0.02 0.03 0.04 0.05

18Mn 12Mn

Strain Rate Sensivity

Eng. Strain (%)

Strain rate : 10^-4s^-1 ~ 10^-1s^-1

10 15 20 25 30 35

-0.05 -0.04 -0.03 -0.02 -0.01 0.00 0.01 0.02 0.03 0.04 0.05

Eng. Strain (%)

Strain Rate Sensivity

Strain rate : 10^-1s^-1 ~ 10²s^-1 18Mn 12Mn

- 104 -

10 15 20 25 30 35 40 45 50

-0.05 -0.04 -0.03 -0.02 -0.01 0.00 0.01 0.02 0.03 0.04 0.05

Eng. Strain (%)

Strain Rate Sensivity

Strain rate : 10⁰s^-1 ~ 10²s^-1 12Mn

- 105 -

×

_≈__

_

_

_

- 106 -

- 107 -

- 108 -

10^-4 10^-3 10^-2 10^-1 10⁰ 10¹ 10² 20000

30000 40000 50000 60000 70000 80000

18Mn 12Mn

Total Absorbed Energy (MPa%)

Strain Rate (s^-1)

10^-4 10^-3 10^-2 10^-1 10⁰ 10¹ 10² 2000

4000 6000 8000 10000

18Mn 12Mn Absorbed Energy Up to 0.1 Strain (MPa%)

Strain Rate (s^-1)

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^′ 

^′ 

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×

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