EJ/T 1167-2018 Metallographic examination of resistance spot weld of guide thimble to grid for pressurized water reactor fuel assembly English, Anglais, Englisch, Inglés, えいご
This is a draft translation for reference among interesting stakeholders. The finalized translation (passing through draft translation, self-check, revision and verification) will be delivered upon being ordered.
ICS
F
Professional Standard of the People’s Republic of China
EJ/T 1167-2018
Metallographic examination of resistance spot weld of guide thimble to grid for pressurized water reactor fuel assembly
压水堆燃料组件导向管与格架电阻点焊的金相检验
(English Translation)
Issue date: 2018-12-28 Implementation date: 2019-03-01
Issued by the Commission of Science, Technology and Industry for National Defense of People's Republic of China
Contents
Foreword
1 Scope
2 Equipment and Materials
3 Sample Preparation
4 Inspection Methods
5 Records and Reports
Metallographic Examination for Resistance Spot Welding of Guide Tubes and Grids for PWR Fuel Assemblies
1 Scope
This standard specifies the equipment and materials, sample preparation, inspection methods, records, and reports for metallographic examination of resistance spot welding joints between guide tubes and grids for PWR fuel assemblies.
This standard applies to metallographic examination of resistance spot welding samples of stainless steel guide tubes to nickel-based alloy grids, as well as zirconium alloy guide tubes to zirconium alloy grids for PWR fuel assemblies.
2 Equipment and Materials
2.1 Equipment
2.1.1 Metallographic specimen hot mounting press.
2.1.2 Metallographic specimen grinding and polishing machine.
2.1.3 Metallographic microscope.
2.1.4 Electrolytic device, adjustable within the range of 0V~30V.
2.2 Materials
2.2.1 Ethanol, chemically pure.
2.2.2 Cold mounting mold.
2.2.3 Cold mounting materials: epoxy resin and hardener.
2.2.4 Transparent hot mounting materials.
2.2.5 Metallographic waterproof abrasive paper: 120#~1200#.
2.2.6 Oxalic acid (C₂H₂O₄·2H₂O), chemically pure.
2.2.7 Hydrofluoric acid (HF), 40%, chemically pure.
2.2.8 Nitric acid (HNO₃), 68%, chemically pure.
2.2.9 Ammonium bifluoride (NH₄HF₂), chemically pure.
2.2.10 Chromium trioxide (CrO₃), chemically pure.
2.2.11 Electrolytic etching solution: prepared from 10g oxalic acid (2.2.6) and 90 mL water.
2.2.12 Zirconium alloy chemical polishing solution: prepared from 10 mL hydrofluoric acid (2.2.7), 45 mL nitric acid (2.2.8), and 45 mL water.
2.2.13 Zr-4 alloy etching solution: prepared from 1g ammonium bifluoride (2.2.9), 10g chromium trioxide (2.2.10), and 100 mL water.
2.2.14 M5 alloy etching solution: prepared from 6g ammonium bifluoride and 100 mL water.
3 Sample Preparation
3.1 Sampling
3.1.1 Transverse Sample Sampling
As shown in Figure 1, first cut along the A-A plane approximately 1mm from the edge of the weld spot to obtain a segment about 10mm~15mm long. Then cut the sample into two parts along the B-B plane.
3.2 Mounting
If necessary, cold mounting or hot mounting methods may be used. Before mounting, the sample surface can be cleaned of oil stains using organic solvents such as ethanol. The mounting material shall be transparent, and after solidification, the weld spot of the sample shall be clearly visible.
3.3 Grinding
Grind the sample sequentially using abrasive paper from coarse to fine grit until approaching the center of the weld spot.
3.4 Mechanical Polishing
Samples of stainless steel and nickel-based alloy welds require mechanical polishing. After polishing, the sample surface shall be bright and free of obvious scratches.
3.5 Etching
3.5.1 Stainless Steel and Nickel-based Alloy Weld Samples
Using the sample as the anode and stainless steel as the cathode, perform electrolytic etching in the electrolytic etching solution (2.2.11). The voltage should preferably not exceed 5V, with an electrolysis time of 10s~20s. The nugget shall be clearly visible when observed under 50x~100x magnification.
3.5.2 Zirconium Alloy Weld Samples
3.5.2.1 For Zr-4 alloy weld samples, wipe with zirconium alloy chemical polishing solution (2.2.12) for 15s~20s to remove scratches, then wipe with Zr-4 alloy etching solution (2.2.13) for 15s~20s to reveal the nugget. The nugget shall be clearly visible when observed under 50x~100x magnification.
3.5.2.2 For M5 alloy weld samples, wipe with zirconium alloy chemical polishing solution (2.2.12) for 15s~20s to remove scratches, then wipe with M5 alloy etching solution (2.2.14) for 15s~20s to reveal the nugget. The nugget shall be clearly visible when observed under 50x~100x magnification.
3.5.2.3 Etching of other zirconium alloy weld samples may refer to the above methods.
4 Inspection Methods
4.1 Stainless Steel and Nickel-based Alloy Weld Samples
Examine under a metallographic microscope whether the sample has formed a nugget structure and whether the nugget shape is uniform and symmetrical.
If necessary, photograph the sample. The field of view should include the grid strap, the complete nugget, and the guide tube, as shown in Figure 3.
4.2.2 Defect Inspection
Examine under a metallographic microscope at 100x magnification for the presence of unmelted metal areas around the nugget, as well as defects such as porosity and cracks within the nugget. If defects exist inside the weld spot, measure the length L of welding defect number n on the bonding surface within the nugget as shown in Figure 4, and calculate the total dimension ∑Lₙ of internal defects along the joint surface. Measurement results shall be accurate to 0.01 mm. Porosity defects present within the 0.1D range at both ends of the nugget (hatched area in Figure 4) shall be specifically noted.
5 Records and Reports
5.1 Records
