Transcript Residual Stress Build Up Baseline NADCA Test Determine how quickly stress builds?  What happens when tensile drops?  What other factors contribute?  How.

Residual Stress Build Up
Baseline NADCA Test
Determine how quickly stress builds?
 What happens when tensile drops?
 What other factors contribute?
 How virgin base H-13 is affected?

Die Materials Committee
March 5, 2003
Baseline Testing
Pre - Dip tank testing
H-13
Dip Tank
Specimen
2”
each
side
7”
 virgin specimen
 no surface treatments
 polished corners and side
 Proto X-ray
 include corners
 Case
Western specified
measurement points
 baselines
All corners square +.003” to -.003”
All corners have .010” radius
Cycles till measured
0,10,100,500,1000,5000,10000,15000
 Dip tank testing – no v or p

H-13
Dip Tank
Specimen
2”
each
side
Immersion aluminum




7”




All corners square +.003” to -.003”
All corners have .010” radius
12 seconds immersion
24 seconds air cool
Water based lube 50:1
Repetitive cycles
X-ray diffraction measure
micro hardness before and
after readings - softening
measure corner cracking
photograph x-ray MEASURED
surface area
Photography not
performed on this 1st
specimen
Proto X-Ray Reading Criteria

location measurements


Corners 1,2,3,4,5,6,7,8
Middle – 1,3,5,7

3 points each corner (avg)
 3 points each middle (avg)
 45o at point #2 (middle) – only for zero
cycles
 Measurements in ksi -1ksi = 6.895Mpa
Error range ∓ 5 with average ∓ 2 (zero-1000)
Error range ∓ 8 with average ∓ 5 (5000 cycles)
Error range ∓ 8 with average ∓ 4 (10,000 cycles)
Error range ∓ 2 with average ∓ 1 (15,000 cycle)
Phase II – Baseline Testing
Side 5
Side 1
2”
each
side
H-13
Dip Tank
Specimen
.5”
3.5”
• 6ea per side x 4 = 24 points
1”
3.5”
1.0”
Measured corners
Measured middle side
1,3,5,7


Axial 3ea per side x 4 = 12
Trans 3ea per side x 4 = 12
Total of 48 x-ray diffraction
measurements from 36
locations
All corners square +.003” to -.003”
All corners have .010” radius
What the following data proves




Tensile relieved by cracking
Tensile rebuilds to higher levels
Subsequent cracking develops
Each time tensile drops to lower level.
No Dip Cycles - Baseline
H-13 Specimen
No Cycles
Corner
1
2
3
4
5
6
7
8 +5
Compressive
Tensile
Axial KSI
Error +or- 2 to 4
-14
-12
-17
-20
-4
-8
-8
-11
-5
-7
-13
-20
-12
-11
-1
-11
-19
-5
-9
-9
-18
-13
-6
Transverse KSI - Point 2
Error +or- 2 to 4
-56
-64
-64
-56
-51
-53
-64
-55
45o - Point 2
Error +or- 1 to 3
-36
-48
-36
-30
-23
-38
-42
-25
Middle
1
3
5
7 +6
-9
-8
-22
-14
-6
-20
-16
12
-21
-61
-61
-65
-56
-53
-59
+5
+3
-48
-51
Polishing after machining creates compressive
-55
-61
-56
-58
values.
-38
-37
-40
-22
All but 4 measurements indicate polished compression
10 Cycles
H-13 Specimen
10 Cycles
Corner
Compressive
Axial KSI
Error +or- 2 to 4
+61
+59
+53
+56
+63
+62
+61
+48
+64
+53
+67
+50
+63
+50
+66
+69
1
2
3
4
5
6
7
8
+64
+65
+68
+52
+55
+55
+58
+69
1
3
5
7
+14
+11
+40
+42
+17
+27
+48
+39
After only 10 cycles all
Tensile
Transverse KSI
Error +or- 2 to 4
Middle
+15
+25
+25
+31
+30
+43
+25
+30
+20
+23
+39
+42
+29
+40
+45
+26
readings indicate high tensile levels
All compressive stress converts to tensile
100 Cycles
H-13 Specimen
100 Cycles
Corner
Axial KSI
Error +or- 2 to 3
+48
+48
+47
+54
+48
+48
+41
+40
+47
+43
+53
+42
+45
+38
+57
+57
1
2
3
4
5
6
7
8
+41
+49
+47
+30
+39
+57
+42
+51
1
3
5
7
+12
+12
+14
+30
+35
+24
+11
+28
+16
+37
+37
+28
At 100 cycles tensile values have
Compressive
Tensile
Transverse KSI
Error +or- 2 to 3
Middle
+19
+33
+20
+38
decreased
+20
+22
+35
+38
slightly
+30
+24
+35
+24
Tensile stress values reduced by cracking
500 Cycles
H-13 Specimen
500 Cycles
Corner
Axial KSI
Error +or- 1 to 2
+55
+53
+51
+55
+58
+48
+49
+45
+56
+52
+53
+47
+57
+52
+59
+58
Compressive
Tensile
Transverse KSI
Error +or- 1 to 2
1
2
3
4
5
6
7
8
+53
+57
+66
+53
+55
+58
+54
+55
1
3
5
7
+17
+24
+19
+34
+36
+33
+34
+28
+48
+30
+19
+28
+21
+27
+41
+44
+39
+28
+46
+45
At 500 cycles tensile values are again increasing
Middle
Tensile stress again on the rise
+32
+33
+31
+30
1000 Cycles
H-13 Specimen
1000 Cycles
Corner
Axial KSI
Error +or- 1 to 3
+53
+54
+51
+50
+71
+64
+36
+36
+58
+57
+54
+50
+64
+61
+71
+48
Compressive
Tensile
Transverse KSI
Error +or- 1 to 2
1
2
3
4
5
6
7
8
+61
+51
+69
+44
+57
+61
+67
+67
1
3
5
7
+44
+42
+44
+44
+42
+54
+42
+40
+54
+42
+41
+42
+42
+41
+42
+49
+46
+36
+49
+46
At 1000 cycles tensile values are almost at same level
Middle
+44
+40
+42
+36
as 10 cycles
Tensile stress approaching values seen at
10 cycles
5000 Cycles
H-13 Specimen
5000 Cycles
Corner
Axial KSI
Error +or- 2 to 9
+70
+70
+53
+58
+72
+70
+62
+69
+87
+81
+76
+60
+87
+65
+68
+66
Compressive
Tensile
Transverse KSI
Error +or- 3 to 8 range
1
2
3
4
5
6
7
8
+73
+64
+72
+53
+83
+69
+81
+66
1
3
5
7
+31
+27
+34
+54
+47
+37
+45
+38
+59
+46
+35
+35
+30
+49
+44
+45
+41
+38
+58
+54
At 5000 cycles tensile values are almost at same level
Middle
+43
+60
+55
+47
as 10 cycles
Tensile stress continuing increase
10000 Cycles
H-13 Specimen
10000 Cycles
Corner
Compressive
Axial KSI
Error +or- 1 to 6
+84
+84
+81
+80
+71
+77
+78
+77
+87
+85
+84
+73
+90
+97
+81
+86
1
2
3
4
5
6
7
8
+75
+81
+79
+79
+77
+88
+76
+83
1
3
5
7
+32
+35
+33
+39
+10
+41
+39
+59
At 10000 cycles tensile
Tensile
Transverse KSI
Error +or- 2 to 8 range
Middle
+42
+40
+37
+59
+23
+48
+51
+53
has increased above
+53
+49
+31
+56
+75
+13
+55
+51
the 5000 cycle point
Tensile stresses at highest levels
15000 Cycles
H-13 Specimen
15000 Cycles
Corner
Compressive
Axial KSI
Error +or- 1 to 2
+67
+75
+73
+65
+69
+70
+59
+54
+66
+57
+72
+76
+72
+73
+62
+65
1
2
3
4
5
6
7
8
+50
+61
+59
+38
+48
+72
+76
+43
1
3
5
7
+32
+34
+37
+37
+27
+34
+45
+41
At 15000 cycles tensile
Tensile
Transverse KSI
Error +or- 1 range
Middle
+30
+50
+52
+23
+37
+31
+26
+50
+55
+33
+52
+53
values move lower again
+50
+29
+47
+46
Tensile stress drops off again – by larger amount
when visible cracking develops
What was confirmed?
 Cycling of tensile stresses and micro cracking
occurs on first 10 shot of unprotected steel.

Virgin steel with no surface treatment and only
polished compression, changes rapidly
to tensile

stresses increases between 100 &
10000 cycles

Visible tensile stress reading at 15000 occurs

Beneficial prior to use to induce high
levels of subsurface compressive stress
values when die is NEW to prevent initial
cracking.