06- industry welding update.• hardness testing is often applied and used as criterion for temper...

Welding Update (Overview, Code Cases, and Alloy 52)

Industry/U.S. NRC Materials Program Meeting Rockville, MD

Thursday June 5, 2013

Steve McCracken EPRI Welding & Repair Technology Center

2 © 2013 Electric Power Research Institute, Inc. All rights reserved.

• Welding & Repair Technical Issues in ASME Section XI

– Will be a single reference for WRTC members to review status and new code changes and initiatives

– Intent is to provide a “living” document that is updated on a yearly basis

– Will include significant Section XI issues and revisions

– Will provide status of on-going activities

New Report on ASME Section XI Welding Issues

EPRI Report1025169

Key Contributors to first issue: Dick Smith, Nick Mohr,

Dave Waskey, Darren Barborak, Steve McCracken


Validity of Hardness as a Measure for Temperbead HAZ Toughness

Simulated PWHT for Temperbead Qualifications Alternate Impact Test Rules for Temperbead Qualifications Elimination of Hydrogen Bakeout for SMAW Temperbead Methods to Validate Chromium Recovery Interpass Temperature Controls for Temperbead and Weld

Overlays Excavate and Weld Repair Code Case Status of Code Cases

- N-638-7, N-666-1, N-740-2, N-786, N-789, N-818 Appendices Include August 2012 ASME WGW – NRC Staff

Meeting Presentations

Report 1025169 Table of Contents


Code Case N-818 Fitness for Service

Steve McCracken, Joshihisa Sekinuma, Steve Swilley, Sam Ranganeth, Owen Hedden, Dave Cowfer, Eric Willis

References: 1. S.L. McCracken, S.M. Swilley, Y. Sekinuma, O. Hedden, D. Cowfer, S. Ranganath, “Proposed ASME Section III

Code Case – Reduction of NDE Weld Repairs,” ASME PVP 2011 Conference, Baltimore, MD, USA, PVP2011-57675

2. Technical Advanced Nuclear Technology: Reduction of American Society of Mechanical Engineers III Weld Fabrication Repairs—Fitness for Purpose. EPRI, Palo Alto, CA: 2010. 1021181.


Section III Code Case N-818 (Fitness for Service)

N-818 was approved December 2011 and will be in Supplement 8 of 2010 Edition of ASME


Section III and N-818 Process Tree

ASME Section III

Workmanship

N-818 Code Case

FFS


• Code Case N-818 is intended for ASME Section III new construction - Applies when Section III radiography detects rejectable flaws

- Uses simple acceptance criteria based upon ASME Section XI (2009 and later) PSI acceptance criteria

- Minimizes or eliminates new construction weld repairs that have caused many instances of Stress Corrosion Cracking

- EPRI did extensive UT work to demonstrate ability to detect and size construction-type flaws in full weld volumes

- EPRI is currently working to resolve Regulator concerns with using UT in lieu of RT

Code Case N-818 Background


Excavate and Weld Repair (EWR)

Reference: Topical Report: Application of the Excavate and Weld Repair Process for Repair and Mitigation of Alloy 182 and 82 in PWRs. EPRI, Palo Alto, CA: 2010. 1021012. Presentation

Steve McCracken, Eric Willis, Jon Tatman, Pete Ricardella, Dick Smith, Brad Thigpen, Jack Spanner

Will cover in “Mitigation – Excavate and Weld Repair” Presentation – Day 2, Thursday June 6th


Temper Bead Hardness Requirements

Steve McCracken, Dick Smith, Darren Barborak

References: 1. S.L. McCracken, R.E. Smith and D. Barborak, “Validity of Hardness Criteria to Demonstrate Acceptable Temper

Bead HAZ Impact Properties for Nuclear Power Applications,” ASME PVP Conference, Paris, France, July 2013, PVP2013-97793 (accepted for the conference proceedings)

2. P. Lester, M. Keller, J. Frank, D. Barborak, R.E. Smith, S.L. McCracken, “Temperbead Welding and International Codes,” EPRI Welding and Repair Technology for Power Plants, International EPRI Conference, Marco Island, FL, June 2012

3. Welding and Repair Technology Center: Welding & Repair Technical Issues in ASME Section XI. EPRI, Palo Alto, CA: 2012. 1025169.

4. Presentation, “Validity of Hardness to Demonstrate Acceptable Temper Bead HAZ Impact Properties in Nuclear Applications (Reference PVP2013-97793)”, ASME Section IX Meeting; Miami, Florida; May14, 2013


• EN/ISO codes, standards and specifications do not directly address temper bead welding similar to ASME

• Hardness testing is often applied and used as criterion for temper bead qualification in addition to impact testing

(reference EN ISO 15614-1)

– Typical acceptance criterion applied 380 HV10 maximum

– Single hardness readings must not exceed maximum

– Hardness measurement required 2mm below surface and 2mm above root of qualification groove weld

• ASME Section IX QW-290.3 specifies hardness as an essential variable for temper bead procedure qualification where book section does not specify impact testing

Hardness Criterion for Temper Bead Qualification – EN/ISO


• Issues with use of maximum harness criterion for temper bead weld procedure qualification – Hardness alone, without knowing the microstructure, is not

adequate for verifying acceptable HAZ tempering by a temper bead welding procedure (i.e., HAZ with acceptable fracture toughness)

Impact testing historically used to verify acceptable fracture toughness

– Rejection by a single hardness reading (as often required in EN/ISO codes) is not reasonable

– Use of maximum hardness criterion can potentially lead to acceptance of HAZ properties with improperly tempered HAZ microstructures with poor toughness

Is Hardness Testing Appropriate for Temper Bead?


Tempered Martensite Has Superior Impact Properties

• Top curve - tempered martensite has superior impact energy from high to low temperatures

• Middle curve - mixed microstructures of tempered martensite plus tempered bainite shows sharp temperature transition

• Bottom curve - tempered martensite plus tempered pearlite has poorest impact energy

From Lundin & Mohammed [7]


EPRI Temperbead Testing on P-3 Gr-3 Materials

• Ambient temperature consistent layer machine GTAW temperbead

• ER80S-B3L filler metal

• Charpy specimens taken at 1/4T location

• HAZ and UBM charpy specimens are alternated along temperbead weld

• Buildup with FCAW after 4 GTAW layers

• SA-508 and SA-533 manufactured by modern fine grain melting practice

• High hardenability & excellent toughness • No simulated PWHT


Charpy Transition Temperature Curves P-3 Gr-3 SA-508 Class 2 Forging (JSW Ht. 02D591-1-1)

Absorbed energy (ft-lb) versus temperature (°F)

~190ft-lb at TNDT+60°F


Hardness Map and Compiled Micro Image P-3 Gr-3 SA-508 Class 2 Forging (JSW Ht. 02D591-1-1)


Histogram of HAZ and First Temperbead Layer P-3 Gr-3 SA-508 Class 2 Forging (JSW Ht. 02D591-1-1)

1.1%

• Only values >240HV plotted

• Values correspond to the HAZ and weld metal

• Values <240HV considered to be base metal

• Only 15 data points out of 1371 (1%) were above 380HV


Maximum Hardness Limit is Not Appropriate

• Superior toughness properties in temperbead HAZ – 165 ft-lb & 80 MLE at drop weight TNDT for the SA-533 plate

– 190 ft-lb & 80 MLE at drop weight TNDT for the SA-508 forging

• Hardness maps reveal only ~1% of counts e 380HV (0.2 kg)

• Low hydrogen processes, controls, and low hydrogen consumables are adequate to provide acceptable margin against HIC in HAZ with e 380HV

• Small random areas of peak micro-hardness do not influence temperbead HAZ toughness

• Hardness may be used only if HAZ microstructure is properly characterized

• EPRI is investigating alternative approaches for using hardness for acceptance of temperbead welding procedures


Impact Testing for Temper Bead Qualification Steve McCracken & Dick Smith

References: 1. S.L. McCracken and R.E. Smith, “Alternative Approach for Qualification of Temperbead Welding in the

Nuclear Industry,” ASME PVP Conference, Toronto, Canada, July 2012, PVP2012-78571 2. Welding and Repair Technology Center: Alternative Rules for Temperbead Qualification. EPRI,Palo

Alto, CA: 2012.1025168. 3. Welding and Repair Technology Center: Welding & Repair Technical Issues in ASME Section XI. EPRI,

Palo Alto, CA: 2012. 1025169.


Temperbead Qualification Issues

• Qualifying temper bead weld procedures on modern low alloy steel (LAS) base materials (e.g., SA-508 forging & SA-533 plate) can be problematic:

– New LAS steels exhibit significantly higher impact energy and much lower transition temperature compared to vintage steels

– Temperature relationship between the Drop Weight (DW) test and Charpy test is altered and prescribed test temperatures often produce misleading HAZ results

• TNDT + 60°F (as set by the drop weight test) is typically on the upper shelf (100% shear) for Charpy testing and data scatter is significant

• Mils Lateral Expansion (MLE) is limited by Charpy specimen geometry and general material properties

• Temperbead procedure requirements may not be met simply because the prescribed Charpy test temperature is too high


Proposed Alternative to Code Case N-638-6

• Alternative provision will:

– Eliminate drop weight test

– Charpy V-notch test temperature may by determined as follows: • Review of test plate CMTR

• Develop a full transition curve for test plate by Charpy V-notch testing

• Select test temperature where Charpy V-notch results in the test plate exhibit 35 to 50 mils lateral expansion

• Test temperature for Charpy tests should be in transition temperature mid-range

TNDT + 60°F

Charpy test BM & HAZ in this

hashed region


Alternative Charpy V-notch Requirements

New Charpy impact test provisions are easily added as alternative in Code Case N-638


ASME Code Cases – Status & Issues


• Eliminate 48 Hour Hold for IWA-4600 SMAW Temperbead Applications (Record # 06-859)

– Will permit final weld NDE as soon as welding and final surface prep is complete

– WRTC provided white paper (EPRI Doc No. 1021076) with technical basis for elimination of the 48 hr hold for SMAW

• Similar and Dissimilar Metal Welding Using Ambient Temperature SMAW Temperbead Technique (RRA 06-09 Record No. 06-859)

– New code case for SMAW ambient temperature temperbead – Eliminates 48 Hour Hold (EPRI Doc No. 1021076) – Same format as N-638

SMAW Temperbead Welding


• N-638-6 Ambient temperature temperbead rules (Board Approved; Supplement 6 to 2010 Edition; Record # 10-650)

– Revision needed to incorporate Section IX QW-290 temperbead qualification rules

– NRC Longstanding Temperbead Open Items

Hardness criterion (euro codes specify hardness for temperbead)

Interpass measurement method/technique

• N-638-7 Ambient temperature temperbead rules

(Approved Standards Comm. XI May 2013; Record # 10-550)

6 Incorporates alternative Charpy testing requirements

6 Permits qualification without simulated PWHT on test plate

Ambient Temperature Temperbead (N-638-6)


Weld Overlay for Repair & Mitigation

• N-754 for Optimized Weld Overlay (OWOL) for PWSCC Mitigation & Repair (Approved Stds Committee XI June 2011; Board Approved; Supplement 6 to 2010 Edition; Record # 06-500)

– OWOL thinner and efficient option for large bore RCS dissimilar metal weld – ISI prior to OWOL installation per N-770-2 – Area increased from 500 in2 to 1000 in2

• N-740-3 Structural Weld Overlay (SWOL) Record # 09-822; Need to address Standards Committee May 2012 letter ballot negatives

– Revise for consistency with N-754 (OWOL) – Response / resolution to NRC negatives – Take out PSI & ISI and reference N-770-2 – Perform ISI prior to SWOL installation per N-770-2 – Include recent changes in MRP-169 – Increase area from 500 in2 to 1000 in2


• N-766 Nickel Alloy Inlay /Onlay for PWSCC Mitigation and Repair (Record # 07-1682; Passed Std Committee XI Dec 2010; Board Approved; Supplement 4 to 2010 Edition) – Rules for pipe ID inlay (~1/8” ID excavation) or onlay (no

excavation) with 52M – Alternative to SWOL and OWOL

• N-803 Ambient Temperature Underwater Laser Beam Welding for PWSCC Mitigation and Repair (Record # 09-1690; Passed Stds Committee XI Feb 2011; Board Approved; Supplement 5 to

2010 Edition) – Rules for laser beam welding of 52M inlay/onlay without need to

drain reactor vessel

– WEC / PCI development and demonstration work at WRTC facilities is complete (moved laser to Lake Bluff)

Inlay / Onlay for Repair & Mitigation


• N-786 Sleeve Reinforcement of Class 2 & 3 Moderate Energy CS Piping

(Adopted; Supplement 5 to 2010 Edition; Record # 09-1691) – Permits 360˚ split sleeve repair of degraded piping (wall thinning

with or without leakage) – Permits reinforcement Type A (open ends) split sleeve or full

structural Type B (sealed ends) split sleeve

N-786 Sleeve Repair for Leak Mitigation


• N-789 Pad Reinforcement for Raw Water Piping (Adopted; Supplement 6 to 2010 Edition; Record # 10-1106)

– Permits 360˚ (sleeve) or partial (pad) repair of degraded raw water service piping (wall thinning with or without leakage)

– Permits structural pad or pressure pad repair of degraded and/or leaking raw water piping

N-789 Pad Repair for Leak Mitigation


Alloy 52M Hot Cracking Steve McCracken & Jon Tatman

References: 1. Welding and Repair Technology Center: Measures to Minimize 52M Hot Cracking on Stainless Steel Base Materials. EPRI, Palo

Alto, CA: 2012. 1025167.

2. S.L. McCracken and J.K. Tatman, Influence of Austenitic Stainless Steel Base Metals on Hot Cracking Susceptibility of High Chromium Nickel-Base Filler Metals, Proc. ASME PVP Conf., July 15-19, 2012, Toronto, ON, Canada Paper No. PVP2012-78614

3. Materials Reliability Program: Preliminary Report – Alloy 52M Hot Cracking Study and Prevention Guide (MRP-310). EPRI, Palo Alto, CA: 2011. 1022885.

4. S.L. McCracken and R.E. Smith, Evaluation of Filler Metal 52M (ERNiCrFe-7A) Hot Cracking When Welding on Cast Austenitic Stainless Steel Base Materials, Proc. ASME PVP Conf., July 17-21, 2011, Baltimore, MD, Paper No. PVP2011-57703

5. S.L. McCracken and R.E. Smith, Behavior and Hot Cracking Susceptibility of Filler Metal 52M (ERNiCrFe-7A) Overlays on Cast Austenitic Stainless Steel Base Materials, Hot Cracking Phenomena in Welds III, Springer-Verlag, pp. 333-352 (2011)

6. S.L. McCracken, B.T. Alexandrov, J.C. Lippold, J.W. Sowards, and A.T. Hope, Hot Cracking Study of High Chromium Nickel-Base Weld Filler Metal 52MSS (ERNiCrFe-13) for Nuclear Applications, Proc. ASME PVP Conf., July 18-22, 2010, Bellevue, WA, Paper No. PVP2010-25787.


EPRI Technical Report 1025167 – December 2012

• Welding and Repair Technology Center: Measures to Minimize 52M Hot Cracking on Stainless Steel Base Materials

• Issue Date: December 2012

• Overview

– Background on hot cracking experience

– Focus on 52M – Hot cracking test approach – Test results – Discussion with measures

to minimize hot cracking – Dilution control & buffer

layer options – Future work


Example of 52M hot cracking on CF8A pipe clad with ER308L

Base metal is SA-351 CF8A 0.019% S, 0.032% P, 0.72% Si

• Hot cracks in 52M weld bead on CF8A CASS base material

• 52M layer (right) shows multiple liquid penetrant crack indications

Issue - 52M and 152 Hot Cracking


Bead-on-Plate Testing Approach

Machine GTAW Setup

52M Beads on CASS Specimens

CASS Specimen Bead-on-Plate Setup

152-152M Beads on CASS Specimens


Range of Materials and Weld Parameters

Material Sample ElementType ID C Si Mn P S Cr Mo Ni Al Co Nb Ti Fe

CASS CF8A 57 0.0227 0.0817 0.756 0.0246 0.0031 19.92 0.400 8.88 0.0014 0.0302 < 0.0040 0.0040 69.8(CASS-a Set) 58 0.0695 0.0752 0.797 0.0319 0.0046 19.93 0.401 8.61 < 0.0010 0.0277 < 0.0040 0.0045 70.0

59 0.0431 0.0695 0.754 0.0288 0.0023 19.98 0.404 8.45 < 0.0010 0.028 < 0.0040 0.0036 70.2

60 0.0405 0.945 0.744 0.0261 0.0019 20.02 0.402 8.45 0.0016 0.0273 < 0.0040 0.0044 69.3

61 0.0483 0.953 0.734 0.0268 0.0019 20.06 0.400 8.39 0.0017 0.0278 < 0.0040 0.0041 69.3

62 0.0581 0.959 0.720 0.0278 0.0027 20.14 0.399 8.34 0.0026 0.0271 < 0.0040 0.0041 69.3

63 0.0446 1.95 0.741 0.0230 0.0017 19.83 0.403 8.46 0.0023 0.0275 < 0.0040 0.0047 68.5

64 0.0581 1.98 0.734 0.0225 0.0018 19.84 0.410 8.45 0.0025 0.0268 < 0.0040 0.0044 68.4

65 0.0470 1.95 0.756 0.0243 0.0025 19.83 0.409 8.53 0.0029 0.0276 < 0.0040 0.0046 68.4

66 0.0531 0.0915 0.743 0.0179 0.0023 19.93 0.406 8.52 <0.0010 0.0206 < 0.0040 0.0026 70.2

67 0.0478 1.93 0.752 0.0440 0.0030 19.82 0.403 8.46 0.0021 0.0276 < 0.0040 0.0051 68.5

68 0.0490 0.982 1.48 0.0255 0.0040 19.77 0.408 8.55 0.0035 0.0277 < 0.0040 0.0043 68.6

PM 54B 0.0166 0.612 0.440 0.0167 0.0324 17.89 2.82 11.85 < 0.0010 0.0345 < 0.0040 0.0064 66.1Type 316L 52B 0.0219 1.70 0.597 0.0187 0.0325 17.78 2.81 12.00 0.0021 0.057 < 0.0040 0.0074 64.8

94B1 0.0219 1.90 0.826 0.0162 0.0042 18.02 2.76 12.37 0.0062 0.0673 < 0.0040 0.0089 63.7

12B1 0.0380 0.537 1.26 0.0277 0.0063 16.30 2.11 10.23 < 0.0010 0.255 0.0187 0.0055 68.8

Plate Type 303 303b (303) 0.0501 0.503 1.69 0.0296 0.324 17.44 0.279 8.26 0.0036 0.0914 0.0096 0.0055 70.7

308L 2L 0.0247 0.436 1.64 0.0193 0.0331 18.48 0.251 9.45 0.0024 0.0471 0.0047 0.0051 69.3Clad Plate 4L 0.0185 0.428 1.68 0.0191 0.0047 19.13 0.249 9.90 0.0023 0.0409 0.0045 0.0053 68.3

308L-Si 1Si 0.0499 0.724 1.76 0.0287 0.180 18.31 0.184 8.80 0.0030 0.0717 < 0.0040 0.0056 69.5Clad Plate 2Si 0.0336 0.938 1.63 0.0236 0.0426 17.88 0.0824 8.93 0.0039 0.0518 < 0.0040 0.0057 70.1

3Si 0.0321 0.968 1.64 0.0242 0.0242 18.04 0.0613 9.07 0.0039 0.0478 < 0.0040 0.0056 69.9

4Si 0.0272 0.996 1.66 0.0242 0.0160 18.30 0.0541 9.25 0.0045 0.0469 < 0.0040 0.0058 69.4

CASS CF8M J92 (pipe) 0.0484 0.552 1.13 0.0214 0.0191 20.93 2.57 11.72 0.0011 0.0336 0.0044 0.0075 62.8

2nd CF8A CASS sample set with desired S range Material Sample Element

Type ID C Si Mn P S Cr Mo Ni Al Co Nb Ti

CASS CF8A A11N 0.0398 0.0826 0.751 0.0121 0.00051 20.55 0.415 8.56 0.0012 0.0255 < 0.0040 0.004(CASS-b Set) A12 0.0444 0.0737 0.771 0.0101 0.0111 20.00 0.424 8.63 0.0045 0.0237 < 0.0040 0.005

A13 0.0471 0.0764 0.771 0.0112 0.0264 20.22 0.424 8.52 0.0023 0.0232 < 0.0040 0.004

A21N 0.0385 0.989 0.746 0.011 0.00089 20.23 0.418 8.45 0.0088 0.025 < 0.0040 0.006

A22 0.0404 0.939 0.768 0.0114 0.0121 19.82 0.422 8.53 0.0010 0.0236 < 0.0040 0.005

A23 0.0450 0.918 0.757 0.0126 0.0326 19.98 0.427 8.46 < 0.0010 0.0234 < 0.0040 0.004

A31N 0.0341 2.02 0.746 0.0093 0.00085 20.01 0.407 8.33 0.0098 0.0253 < 0.0040 0.005

A32 0.0375 1.95 0.761 0.012 0.014 19.65 0.412 8.43 0.0040 0.0323 < 0.0040 0.005

A33 0.0403 1.92 0.765 0.0121 0.0342 19.79 0.420 8.34 0.0042 0.0233 < 0.0040 0.005

B1N 0.0361 0.091 0.734 0.0047 0.0013 20.40 0.413 8.60 < 0.0010 0.0003 < 0.0040 0.003

B2 0.0430 1.96 0.760 0.0263 0.0124 19.69 0.412 8.38 0.0013 0.0235 < 0.0040 0.007

C1 0.0359 0.956 1.45 0.0117 0.0148 19.83 0.423 8.40 < 0.0010 0.0233 < 0.0040 0.004

Weld parameters for GTAW

No. Alloy AWS Spec. Heat No. Cr Fe Si Mn C P S

a 52M ERNiCrFe-7A NX76W5TK 30.12 8.68 0.11 0.77 0.02 0.003 0.00005 0

b 52M ERNiCrFe-7A NX74W8TW 29.75 8.75 0.11 0.74 0.02 0.01 0.001 0

d 52M ERNiCrFe-7A NX7588TK 29.95 8.81 0.12 0.75 0.023 0.004 0.0006 0

c 52MSS ERNiCrFe-13 NX77W3UK 29.49 8.79 0.11 0.31 0.023 0.004 0.00005 2

e 52i ERNiCrFe-15 187775 26.98 2.55 0.05 3.04 0.04 0.002 0.001 2

f 82 ERNiCr-3 EXD63590 21.35 0.53 0.16 2.9 0.033 0.003 0.001 2

GTAW Filler Wire (phase 1)

No. Alloy AWS Spec. Heat No. Cr Fe Si Mn C P S

B 52M ERNiCrFe-7A NX74W8TW 29.75 8.75 0.11 0.74 0.02 0.01 0.001 0

E 52i ERNiCrFe-15 187775 26.98 2.55 0.05 3.04 0.04 0.002 0.001 2

F 82 ERNiCr-3 EXD63590 21.35 0.53 0.16 2.9 0.033 0.003 0.001 2

M 52MSS ERNiCrFe-13 HV1500 29.49 0.034 0.001 0.211 0.033 0.002 0.001

N 52 ERNiCrFe-7 NX6966JS 29.14 8.97 0.18 0.72 0.007 0.003 0.003 0

O 622 ERNiCrMo-10 XX2464BK 20.64 2.30 0.03 0.23 0.005 0.01 0.0001

GTAW Filler Wire (phase 2)

No. Alloy AWS Spec. Lot No. Cr Fe Si Mn C P S Nb Ti

i 152-A ENiCrFe-7 98937 28.7 7.87 0.58 2.7 0.028 0.003 0.001 1.36 0.27

j 152-B ENiCrFe-7 14633 28.8 7.84 0.48 3.15 0.028 0.005 0.004 1.54 0.07

k 152-C ENiCrFe-7 N00170 28.5 8.73 0.393 4.53 0.038 0.005 0.002 1.991 0.1

g 152M-A ENiCrFe-7 327781 29.2 7.77 0.36 3.52 0.039 0.003 0.001 1.69 0.08

h 152M-B ENiCrFe-7 17872 28.7 7.99 0.45 3.39 0.03 0.008 0.006 1.72 0.07

l 152M-C ENiCrFe-7 162663 28.8 7.96 0.48 3.77 0.032 0.011 0.003 1.79 0.06

SMAW Electrodes (phase 3)


Bead Profile and Hot Crack Characterization

82 Bead on A31N sample

25x Micrograph 82 on A31N sample

• Measured and recorded the following: Composite zone areas, toe angle(s), depth,

width, and penetration

• Calculated dilution by area method • Inspected for cracks at 50x • Cracks graded as follows:

TNC – Total Number of Cracks > 0.2 mm TCL – Total Crack Length (sum of all

cracks) MCL – Maximum Crack Length (single

largest crack length) Cracks within d 0.2 mm proximity are

counted and sized as one crack Cracks categorization as:

– Surface Crack – Midwall Crack – Fusion Line Crack


Susceptibility Plot with Sulfur (GTAW – 2nd data set)

CF8A


Susceptibility Plot with Silicon (GTAW – 2nd data set)

CF8A


Maximum Crack Length vs Dilution (GTAW & SMAW)


Dilution vs Silicon – Crack No Crack Plot (GTAW & SMAW)


S+P vs Si with Crack Free Region (GTAW Phase 1 &2)


Crack Severity Chart (Phase 2 CASS-b Set)

Filler Metal 82 (F) 52i (E) 52M (B) 52 (N) 52MSS (M) Base Metal Si S P Mn Mo Parameter No. 2 1 4 2 1 4 2 1 4 2 1 4 2 1 4 Crack Rank1 1 2 1 1 A11N 01 2 2 1 1 A12 1 11 3 2 1 1 A13 1 1 22 1 2 1 1 A21N 1 1 1 32 2 2 1 1 A22 1 1 1 1 1 52 3 2 1 1 A23 1 1 1 1 1 53 1 2 1 1 A31N 1 1 1 1 1 1 63 2 2 1 1 A32 1 1 1 1 1 1 1 1 1 1 103 3 2 1 1 A33 1 1 1 1 1 1 1 1 1 91 1 2 1 1 B1N 03 3 3 1 1 B2 1 1 1 1 1 1 1 1 1 1 102 2 2 3 1 C1 1 1 1 1 4

Base Metal 1 8 9 0 6 6 0 6 6 0 3 4 0 1 5 Weld MetalNo. 18 12 12 7 6 Crack Rank


Filler Metal Comparison Plot (Phase 2 CASS-b Set)


• Dilution Control

– GTAW keep dilution d 55% (52M, 52i, 52MSS, or 82) – SMAW keep dilution d 35% (152 & 152M)

• Composition Control – Use CMTRs to understand diluted composition – Maintain following limits in weld deposit

S < 0.020 wt%; Si < 0.60 wt%; S+P < 0.035 wt%

– Consider effect of base metal S on dilution – Consider influence of joint geometry and welding position

on dilution

Approach & Considerations to Prevent Hot Cracking


• Process Parameter Controls

– Develop or identify optimum welding parameters and techniques to minimize dilution

– The power ratio equation is a good method to understand and control dilution for a given set of weld and base metals

– Understand that parameters developed for low sulfur base materials may be significantly different on higher sulfur and higher silicon base materials



• Bead Placement Control and Buffer Layers

– Use bead placement to minimize dilution

– Buffer may be ER309L, ER308L – Data shows 52MSS may be good buffer layer choice – Data shows 82 is not a good buffer layer choice – Mo bearing buffer layers currently under investigation



• Use Design of Experiments (DOE) to define future testing – Select Mo as target element for study – Use data for input to new filler metal development

• Continue testing on 2nd set of CASS samples – This set provides desired fidelity of Si & S compositions

that was not achieved in 1st sample set • Investigate GTAW with magnetic arc stirring on CASS

samples • Investigate CMT low dilution process

Future Work and Testing


Questions or Comments?

Welding and Repair Technology Center


Together…Shaping the Future of Electricity

06- industry welding update.• hardness testing is often applied and used as criterion for temper...

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