Re-inspection of titanium welding materials

Hello! The question you raised is very typical; it is a confusion that often arises in titanium welding. Let’s break it down step by step. ### Question 1: Regarding the discrepancy in retesting the mechanical properties of the deposited metal, your observation is accurate; indeed, there is a \"gap\" between the standards here. 1. **Key conflict point**: * **NB/T 11270**, as a standard specific to welding materials for titanium and titanium alloys, requires retesting of the welding wires, with tests including the **chemical composition and mechanical properties of the deposited metal**. This is from the perspective of ensuring the ultimate performance of the welded joint. * **NB/T 47018.7** and **GB/T 3623 are product standards for welding wires, and they specify the acceptance requirements for the welding wires **themselves**. For wire products, only their **chemical composition** (which is the basis for determining the composition of the deposited metal) and **appearance, dimensions, etc. of the wire** are typically inspected. They generally do not specify the mechanical properties of the deposited metal, as these need to be determined through welding procedure qualification test plates. 2. **Solution for “how to conduct re-inspection”**: When NB/T 11270 requires re-inspection but the product standards do not specify it, **the requirements of NB/T 11270 shall be followed**. The specific procedure requires **simulated welding process qualification**: * **Prepare test plates**: Use the wire to be retested, and weld test plates of the deposited metal according to a reasonable welding process that can represent its performance (you can refer to the typical process for wires of that grade or existing welding process qualifications). * **Processing specimens**: Standard tensile specimens, bending specimens (if required), etc. are fabricated from the test plates. * **Testing and Evaluation**: Mechanical property tests (tensile strength, yield strength, elongation, etc.) are conducted on these specimens. The test results must meet the **performance requirements for the deposited metal of this type of welding wire as specified in the NB/T 11270 standard**, or they must conform to the **criteria outlined in the design documents or procurement technical agreements**. **In simple terms**: Re-testing the mechanical properties of the deposited metal does not involve testing the welding wire itself; instead, test plates are welded using this batch of welding wire according to standard methods, and then those test plates are subjected to mechanical property tests. This is equivalent to a small-scale process validation for that batch of welding materials. ### Question 2: The inspection items that should be included in the warranty for titanium welding materials – your understanding is generally correct, but it is necessary to add details and clarify the priorities. 1. **Primary basis**: **Requirements of the procurement technical agreement or contract**. This is a document of the highest priority; if it specifies the contents of the warranty certificate, those specifications must be met. 2. **Standard Basis**: When the contract does not specify otherwise, relevant standards shall be applied. The several standards you mentioned need to be considered together: * **NB/T 47018.1** sets out the general requirements, and Table 1 in it specifies the **minimum requirements** for the \"inspection items\". For titanium welding wire, it indeed only lists “chemical composition” and “radiographic testing (RT)”. **Note**: Here, RT usually refers to the welding joint of the wire coil (if any) or inspections required by specific specifications; it is not mandatory, and the details depend on the agreement between the supplier and the buyer. * **NB/T 47018.7** specifies the requirements for titanium and titanium alloy welding wires. It stipulates that the **bending test** is a **type inspection item** for wire products, rather than a routine **exit inspection item**. * **As a national standard product standard, GB/T 3623** specifies that the factory inspection items typically include **chemical composition** and **dimensional and surface properties**. 3. **Conclusion: A complete quality guarantee certificate for titanium welding wire should generally include the following items**: * **Manufacturer information, product standards (such as GB/T 3623), grade, specifications, batch number, and furnace number**. * **Chemical composition report**: This is a **core and essential** item; it must list the actual content of all specified elements, in compliance with standard requirements. * **Mechanical properties report (not mandatory but important): Although 47018.7 does not require such a report to be provided at the time of delivery, **responsible manufacturers or high-end products usually provide typical mechanical property data for the weld metal produced from this wire grade** (based on their type testing or statistical results). If the purchaser has any requirements, they should be specified in the contract. * **Bending test report**: As above, it is part of the type test items. A standard warranty certificate may not be included, but the manufacturer can be requested to provide their historical type test reports for reference. * **Radiographic Testing (RT) report**: In accordance with Table 1 of 47018.1 or contract requirements. If not specified in the contract, this may not be provided. * **Others**: surface quality, dimensional tolerances, etc. ### Practical advice for you: 1. **Regarding re-inspection**: Specify in the purchase contract or technical agreement that \"re-inspection of welding wires shall be carried out in accordance with NB/T 11270, including re-inspection of the chemical composition and mechanical properties of the deposited metal.\" This prevents disputes at the source. The mechanical property criteria for retesting can be specified as meeting NB/T 11270 or a specific value. 2. **Regarding the warranty certificate**: When placing an order, it should be specified that the warranty certificate must include at least: a **complete chemical composition analysis report, typical mechanical property data of the deposited metal (tensile strength, yield strength, elongation), and a statement indicating compliance with GB/T 3623 or NB/T 47018.7**. If there are any special requirements (such as RT, bending data), they should also be included in the contract. **To summarize**: Re-testing mechanical properties requires \"welding test plates, taking samples, and conducting experiments\"; the key aspect of a quality certificate is the chemical composition, while it is advisable to obtain the mechanical property data from the supplier. Everything is subject to the written contract and technical agreement; clear communication in advance can avoid many subsequent problems. I hope this explanation is helpful to you! .

The core of a warranty certificate is the chemical composition; it is advisable to obtain data on mechanical properties from the supplier. Everything is subject to the written contract and technical agreement; clear communication in advance can avoid many subsequent problems.

There are new technologies that allow for the non-destructive, online measurement of strength parameters (tensile strength and bending strength) at any location in materials or equipment, without the need for test specimens. This technology can be used for incoming material inspection, assessing the impact of welding on material properties, evaluating the effects of heat treatment, and assessing the safety of equipment. 2026 has already been included in the GB standards (GB/T30583-2026).