Do the weld evaluation reports for dissimilar steels cover the welded joints between them?
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This post was last edited by No.1 Shoe Store Chaomuzi on January 11, 2024, at 11:24. 19. Can the welding procedure that has been evaluated as qualified—involving 15CrMoR + Q345R, 16 mm thickness, butt welds, SMAW method, E5515-1CM (R307) electrode, preheating at 120°C, and SR treatment—be applied to welding processes where 15CrMoR and Q345R are welded to each other, provided that all other welding evaluation factors remain unchanged? Specifically: 15CrMoR, 16 mm thickness, butt welds, SMAW method, R307 electrode, preheating at 120°C, SR treatment； Q345R/16mm/butt weld/SMAW/E5515-1CM (R307)/preheating 120℃/SR? Answer: According to paragraph 2 of 6.1.2.1e), it applies. Regarding the weld evaluation mentioned in the example, I have a question: for the physical and chemical test reports of this weld between different steel grades, the tensile test will result in fracture on the 15CrMo side, and the tensile strength is determined based on the properties of the 15CrMo side, which is lower than that of Q345R material. How does it override the strength of the base material and weld of 15CrMo, which is specified as “Q345R/16mm/butt weld/SMAW/E5515-1CM (R307)/preheating at 120℃/SR”? The reason I use this example is that I have encountered a real-world production scenario of this kind.
When conducting welding procedure qualification for dissimilar steels, if the qualification is successful for the combination of 15CrMoR and Q345R, it can indeed be applied to welding of the same material under certain conditions, as welding dissimilar steels typically involves more stringent requirements. However, the tensile strength failure on the Q345R side merely indicates that in this combined weld, Q345R is the weak link. Regarding the welding of 15CrMoR alone, both the base metal and the weld seam need to possess high strength; therefore, the tensile test results obtained from the evaluation of the welding process for 15CrMoR+Q345R do not reflect the actual strength of the weld seam or the base metal when 15CrMoR is welded alone. The coverage of the welding procedure qualification for dissimilar steels regarding the applicability of welding identical materials is based on the versatility of welding procedure parameters, and it does not directly reflect the strength properties of the materials. In standalone welding applications of 15CrMoR, it is also necessary to ensure that the strength of the welds and the base metal meets the design requirements; this may require separate evaluations or necessary adjustments and verifications based on existing process evaluations. .
This rule in the 2023 version has likely been removed
Theoretically, it’s possible, but in actual production, when welding Q345R joints, who would use R 307 welding rods? Unless it’s ****ed
This post was last edited by wanlirn on 2024-1-12 at 09:59. The strength of 15CrMoR at medium and low temperatures is lower than that of Q345R; therefore, partial fracture of it is normal. When the welding heat input is the same, both materials can certainly be used accordingly.
First of all, it’s a good question. In fact, clause 6.1.2.1(e) of NB/T 47014 is derived from clause QW-403.5 in ASME Volume IX. In the ASME Volume IX standard, this clause represents an additional important factor; it only affects the impact properties of the heat-affected zone. It is not applicable when the product standards do not require testing the impact properties of the heat-affected zone. Therefore, when introducing this clause in NB/T47014, it is unclear whether this point was overlooked or not considered carefully; this clause was simply treated as a general evaluation rule. As a result, when specifying the impact properties of the heat-affected zone, this clause can be used to cover the weldability of materials from different categories and groups, without having to take into account other evaluation rules for those categories and groups. That is what leads to the situation that the original poster is puzzled about. The intention of the ASME standard is that, in accordance with the respective welding methods, the specified material categories and grouping rules must be followed. When impact tests on the heat-affected zone are required, this rule comes into effect, thereby helping to reduce the need for impact test specimens.