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