1、STP-PT-085EFFECT OF HOT WIRE FILLER METAL ADDITION ON GTAW HEAT INPUT FOR CORROSION RESISTANT OVERLAYSSTP-PT-085 Effect of Hot Wire Filler Metal Addition on GTAW Heat Input for Corrosion Resistant Overlays and its Resulting Effect on Heat-affected Zone Hardness and Toughness and Corrosion Resistant
2、Overlay Chemical Composition Prepared by: Richard L. Holdren, PE/SWE ARC Specialties Technical Services David A. Hebble, SWE ARC Specialties Technical Services Date of Issuance: June 30, 2017 This report was prepared by ASME Standards Technology, LLC (ASME ST-LLC) and sponsored by the American Socie
3、ty of Mechanical Engineers (ASME) Pressure Technology Codes however, there have been questions raised in terms of whether the secondary power actually contributes to the amount of energy being supplied to the base metal or is consumed in the process of preheating the filler metal. This study will at
4、tempt to quantify what contribution, if any, is provided by the secondary power to affect the resulting HAZ properties and chemical composition of the CRO. 1.1 Project Objective The primary objective of this study was to determine if any technical justification exists for consideration of the additi
5、on or modification of essential variables to include the secondary power from hot wire additions. 1.2 Materials While this topic may be of interest in other industries and applications, it is known to be of concern in these upstream oil and gas applications. ARC Specialties is the leading producer o
6、f automated welding systems used for applying CROs to a variety components, with 300+ systems in operation around the world. While several different welding processes are employed in these systems, the vast majority utilize GTAW-HW. Consequently, the materials chosen for this study will be those mos
7、t commonly employed for these upstream oil and gas applications. The two base metals most commonly employed are quenched and tempered versions of AISI 4130 and 2 Cr 1 Mo (P-5A, Grade 22). In most cases, the forged versions of these base metals are used; however, this adds significantly to the cost.
8、In the original proposal, Grade 22 was the only material to be included in this study, but there is far more 4130 material used than Grade 22. Consequently, to provide more data, pipe grades of the two materials were used because compositionally the pipe and forging materials are virtually identical
9、. Below are the two base metals to be used for this study, and material certs are attached: SA335 Grade P22 Ht #986957 CEIIW= 0.825; 8.625 inches OD x 0.812 inches wall A519 Grade 4130 Ht #J4038 CEIIW= 0.663; 8.625 inches OD x 1.5 inches wall The overlay material was Inconel625 (SFA5.9, ERNiCrMo-3).
10、 The size used was 0.045 inches (1.2 millimeter (mm) diameter. Lincoln offered to supply the filler metal for this work. The type and classification are shown below and the material cert is attached. 0.045 inches 1.2 mm TECHALLOY 625 33SSP Ht #QT594 1This publication uses the technically-correct ter
11、m heat input rate (HIR) to describe the amount of energy input per unit length of weld. This varies from the terminology, heat input (HI), used in ASME BPVC Section IX; however, for the purposes of this publication, the two terms shall be considered synonymous. STP-PT-085: Effect of Hot Wire Filler
12、Metal Addition on GTAW Heat Input for Corrosion Resistant Overlays 2 2 WELD TRIAL MATRIX CRO WELDS Two series of CROs were welded on each base metal for a total of four series. One series for each base metal was welded using conventional parameters where the weld metal deposition rate is approximate
13、ly 2 pounds per hour. The second series for each base metal was welded using newly developed parameters which result in higher deposition rates on the order of 8 pounds per hour. The parameters used for the higher deposition rates actually result in lower heat input rates, so this provided even more
14、 test data. Welding was conducted on pipe coupons using ARCs next generation HVT system. The welding system is capable of welding in a variety of welding positions by rotating the frame holding the turntable and welding torch. The frame can be rotated from 0-90 degrees. Images of the welding system
15、in the two configurations are shown below in Figure 2-1 and Figure 2-2. All of the samples for this study were welded in the flat (1G) position as shown in Figure 2-2. While the plan was to run the samples at pre-established settings, there is a need to make minor adjustments. The primary2amperage,
16、wire feed speed and travel speed can be preset accurately; however, there is a need to make minor adjustments to the secondary3amperage, primary voltage and secondary voltage to stabilize operation and assure good wetting. Every attempt was made to adjust the filler wire guide tube consistently with
17、 respect to the end of the tungsten electrode, however, minor secondary amperage and voltage adjustments are inevitable. Similarly, the entry point of the filler wire was held constant, as much as practicable. For all of these test welds, the filler wire was introduced at the rear of the molten pool
18、, which is typical for hot wire feed, but different from typical cold wire operation, where the wire is most often introduced at the leading edge of the weld pool. Parameters such as travel speed, wire feed speed, background current percentage of peak, step-over, and pulse duration were preset and r
19、emained constant. A Lincoln Power Monitor was used, but the same software is incorporated into the ARC HVT system, so the amperages listed are those displayed on the HMI panel of the system. Comparison of the instantaneous energy with that calculated using the average of the peak and background ampe
20、rage were used. Consequently, heat input rate was calculated per QW-409.1(a). 2“Primary” applies to the electrical energy applied to the arc. 3“Secondary” applies to that energy applied to energize the hot wire. STP-PT-085: Effect of Hot Wire Filler Metal Addition on GTAW Heat Input for Corrosion Re
21、sistant Overlays 3 Figure 2-1: ARC-HVT set for horizontal welding position Figure 2-2: ARC-HVT set for flat welding position STP-PT-085: Effect of Hot Wire Filler Metal Addition on GTAW Heat Input for Corrosion Resistant Overlays 4 Table 2-1 shows the test matrix, with designators for each test weld
22、. The designators A through H were simply used as a shorthand means of identifying the various weld schedules, and the prefixes “22” and “30” were used to identify P22 and 4130 base metals, respectively. “CW” and “HW” refer to cold wire and hot wire, respectively. The numbers following those prefixe
23、s refer to the wire feed speeds in terms of inches per minute. Table 2-1: Welding parameters and resulting heat input rates for P22 and 4130 CRO welds Once the coupons were welded, each was cut in half. Halves of each coupon were subjected to post-weld heat treatment (PWHT) at a temperature of 1,175
24、 oF 635 oC. The P22 coupons were held at the PWHT temperature for 6 hours while the 4130 coupons were held for 4 hours. These temperatures and holding times are typical for upstream oil and gas applications. Samples from each coupon were then removed and subjected to testing and chemical analysis as
25、 described as follows. Schedule Amps Volts Pulse duration, s Background % AmpsAVG Hotwire A Hotwire V Primary Secondary Total WFS / TS22-A CW55 260 12 0.2 / 0.2 50 195 8 0 0 55 17.55 0.00 17.55 6.87522-B CW100 375 13.5 0.08 / 0.08 85 347 20 0 0 100 14.05 0.00 14.05 522-C HW50 260 11.4 0.2 / 0.2 50 1
26、95 8 71 1.8 50 16.67 0.96 17.63 6.2522-D HW75 260 12 0.2 / 0.2 50 195 8 96 2.4 75 17.55 1.73 19.28 9.37522-E HW100 260 12 0.2 / 0.2 50 195 8 116 2.9 100 17.55 2.52 20.07 12.522-F HW150 375 13.5 0.08 / 0.08 85 347 20 65 1.9 150 14.05 0.37 14.42 7.522-G HW225 375 13.5 0.08 / 0.08 85 347 20 147 4.0 225
27、 14.05 1.76 15.81 11.2522-H HW300 375 13.5 0.08 / 0.08 85 347 20 162 4.7 300 14.05 2.28 16.33 15Welding Trial Parameter Matrix - P22 / 625 CROPrimary (Arc) EnergyTravel speed, in/minSecondary (Hot Wire)Wire feed speed, in/minHeat Input Rate, kJ/inSchedule Amps Volts Pulse duration, s Background % Am
28、psAVGHotwire A Hotwire V Primary Secondary Total WFS / TS30-A CW55 260 12 0.2 / 0.2 50 195 8 0 0 55 17.55 0.00 17.55 6.87530-B CW100 375 13.5 0.08 / 0.08 85 347 20 0 0 100 14.05 0.00 14.05 530-C HW50 260 11.4 0.2 / 0.2 50 195 8 69 1.8 50 16.67 0.93 17.60 6.2530-D HW75 260 12 0.2 / 0.2 50 195 8 95 2.
29、4 75 17.55 1.71 19.26 9.37530-E HW100 260 12 0.2 / 0.2 50 195 8 114 3.3 100 17.55 2.82 20.37 12.530-F HW150 375 13.5 0.08 / 0.08 85 347 20 68 1.9 150 14.05 0.39 14.44 7.530-G HW225 375 13.5 0.08 / 0.08 85 347 20 146 4.0 225 14.05 1.75 15.80 11.2530-H HW300 375 13.5 0.08 / 0.08 85 347 20 183 4.7 300
30、14.05 2.58 16.63 15Welding Trial Parameter Matrix - 4130 / 625 CROPrimary (Arc) EnergyTravel speed, in/minSecondary (Hot Wire)Wire feed speed, in/minHeat Input Rate, kJ/inSTP-PT-085: Effect of Hot Wire Filler Metal Addition on GTAW Heat Input for Corrosion Resistant Overlays 5 3 TESTING PROGRAM The
31、purpose of the testing was to determine if the variations in heat input rate had an effect on resulting HAZ hardness and CRO chemical composition. Conventional testing included Vickers microhardness testing use a 10 kilogram (kg) load and chemical analysis of the CRO deposit using a portable X-ray f
32、luorescence (PMI) gun. There was also an attempt to measure the area of the CRO deposit to see if any correlation existed between that and resulting weld and HAZ properties. Descriptions of the methodologies for each of these tests appear below. 3.1 Hardness Testing As mentioned above, hardness test
33、ing was performed using the Vickers hardness method with a 10 kg load. Testing was performed in accordance with ASTM E92. Specific test locations are shown in Figure 3-1 below. Figure 3-1: Microhardness test locations for CRO welds Indentations #1 through #9 were located per the requirements of NACE
34、 MR0175. To alleviate some of the vagueness of the standard with respect to the location of the HAZ indentations (#4, #5, and #6), those readings were taken at a distance of 0.75 mm from the weld interface (fusion line). In the standard, it states that indentations “.should be entirely within the he
35、at-affected zone and located as close as possible to, but no more than 1 mm from, the fusion boundary between the weld overlay and HAZ.” Experience has shown that this permissible variation allows for a wide variation in hardness results. In the diagonal traverses (Indentations #10 through #14 and #
36、15 through #19) these variations are verified. Such variability is expected when hardness testing using low loads is performed. Lincoln offered to perform hardness mapping 0.75mm1.5mm1 3467258910111213141516171819FusionLineHeat-affectedzone10mm13mm13mm10111213140.25mm1.0mmSTP-PT-085: Effect of Hot W
37、ire Filler Metal Addition on GTAW Heat Input for Corrosion Resistant Overlays 6 of the P-22 as-welded samples. While not discussed here, those results are included for information as Appendix A of this publication. 3.2 Chemical Analysis As is typical for the qualification of CROs, chemical analyses
38、were performed on prepared surfaces of the welds. Analysis was performed using a portable X-ray fluorescence instrument. As only a single layer of CRO was used, most of the deposits were less than the standard measurement distance of 0.125 in 3 mm above the base metal surface. It should be pointed o
39、ut that the deposit thickness measurement for applications governed by American Petroleum Institute (API) standards is different from that used in ASME BPVC Section IX. For API standards, the thickness of the overlay is measured from the base metal surface while, in ASME BPVC Section IX, the distanc
40、e measured is from the fusion line (weld interface), which is the boundary between the weld metal zone (WMZ) and HAZ. Figure 3-2 graphically illustrates this difference. Figure 3-2: CRO chemical analysis locations for API vs ASME qualification 3.3 Deposit Area Measurement The final method used to an
41、alyze effects of different heat input rates was measurement of the cross-sectional area of deposited weld metal. To make this determination, two methods were used. The first was an attempt to physically measure the cross section of individual beads with mechanical measurement devices. This proved to
42、 be both difficult and subject to measurement errors. It was also influenced by the varying amounts of dilution present making it difficult to develop clear relationships. The second method, referred to here as the Jackson Method, was named after a former Welding Engineering professor, Clarence E. J
43、ackson. Professor Jackson spent much of his professional career studying submerged arc welding (SAW) and developing SAW fluxes. In a number of his studies, he was quite successful in developing relationships between weld bead area and weld metal properties. In many cases, he was able to find much cl
44、oser correlation between weld bead area and weld mechanical properties than could be found using conventional heat input rate. When Professor Jackson was doing this work, the most accurate measuring instrument in a lab was typically an analytical balance. This method involved photographing a weld cr
45、oss section, cutting sections of the weld deposit, and then comparing the weight of the weld cross section with that of a known area of the photo. Following are the steps to determining weld bead area using the Jackson Method: 1. Image of weld sample A / B shown in Figure 3-3. 2. Picture is taken wi
46、th sample positioned on a background that has a 1 inch x 1 inch square and 2 inches weld width scribe lines. 3. Golden rectangles show the areas being determined which are 2 inches wide (determined by the scribe lines) and a line flush with the original base metal surface. 4. The image is printed an
47、d the 1 inch square and golden rectangles are cut out. TwtQ-APIChemicalAnalysisweldinterfacetQ-ASMESTP-PT-085: Effect of Hot Wire Filler Metal Addition on GTAW Heat Input for Corrosion Resistant Overlays 7 5. These cutouts are weighed on an electronic balance a. Weight of the 1 inch square provides
48、a weight per square inch b. Weight of golden rectangle (weld bead area) provides the weight of the weld bead area 6. Dividing the weight of the weld bead area by the weight per square inch yields an area per 2 inches weld bead width, which is reported as CRO Area in Tables 2, 3, 4 and 5. Figure 3-3:
49、 Image of P22 sample A/B used for weld bead area determination using Jackson Method 3.4 CRO Test Results Test welds were produced using the parameters listed in Table 2-1. Each sample was then subjected to the three types of tests described above: microhardness, chemical analysis, and deposit area measurement. Additionally, macro-sections of each sample were prepared, etched, and imaged. Macro-images of the P22 samples appear in Figure 3-4 A-D, and those for the 4130 samples are shown in Figure 3-5 A-D. Sample IDs are shown in RED. Primary heat input rates in un
