ЗАСТОСУВАННЯ ІНДЕКСУ ПРАЦЕЗДАТНОСТІ ПРОЦЕСУ ПРИ ВИБОРІ ЗВАРЮВАЛЬНИХ МАТЕРІАЛІВ

Abstract

The lists of construction materials, welding materials, welded products and areas of application of welding are constantly increasing. For each welded product should be chosen welding, taking into account the variability of the characteristics of welds.This determines the urgency of research on the effectiveness of modern statistical methods on the choice of welding materials.Welding processes are special processes that require validation in the face of changing values of the quality characteristics of welded joints. Existing approaches to determining the acceptability of welding materials do not exclude the possibility of non-compliance with the requirements for welds in some areas.Analysis of the literature shows that the traditional approach to confirming the acceptability of welding materials for a given welded product, based on the criterion of finding all experimentally obtained values within the range of acceptable values. This approach does not take into account the mathematical expectation and the standard deviation of the quality of welds. The application of statistical sampling requires large sample sizes and focuses on the acceptance or rejection of individual batches of welding consumables. However, in modern conditions, the supply of welding consumables should betreated as a process.In the general case, the ability of the process to meet the established requirements is determined by the index of efficiency of the process. However, the effectiveness of this approach to determine the possibility of applying welding materials to a given product needs to be studied. The research objective is to determine the effectiveness of assessing the acceptability of welding materials for welding a given product by applying the index of efficiency of the welding process of the test material on controlled quality indicators of the weld.A study of the application of the efficiency index to determine the acceptability of welding materials in the selection of welding wire for the manufacture of bridge beams from steel S355J0WP. State building norms ДБН B.2.3-26: 2010 establish requirements for the minimum allowable value (LSL) of welds of the bridge beam on certain indicators of mechanical properties of the weld metal.The use of the traditional approach and performance index was investigated to confirm the acceptability for the bridge beam welding with Chord wire S2 flux flux Ok 10.71, Chord S2Ni1Mo flux wire Flux Ok 10.71, X-3Si1 wire in a mixture of M21 gases. The mechanical properties of the weld metal were determined by the yield strength (σт), temporary fracture toughness (σв), relative elongation (δ5), relative narrowing (ψ).According to both the traditional approach and the performance index, the Chord wire S2 is not acceptable, and the Chord wire S2Ni1Mo is acceptable for submerged arc welding Flux Ok 10.71 bridge beams. Thus, when welding under Flux Ok 10.71, both approaches gave the same result. However, for X-3Si1 wire welding in a mixture of M21 gases, the studied approaches gave different conclusions. According to the traditional approach, welding with X-3Si1 wire in a mixture of M21 gases is acceptable, and according to the process performance index, it is not acceptable for the bridge crossing beam.Studies have shown that the results of assessing the acceptability of welding materials by the traditional criterion (stay of all experimentally obtained data within the range of allowable values) by 87% coincide with the results of the capability of the process index (Cpk ≥ 1.67). In the study of the acceptability of the use of X-3Si1 wire for welding a given product, the classical approach showed the acceptability of the welding wire. The efficiency of the welding process on the temporary resistance to failure (σв) and elongation (δ5) had values less than 1.67, which indicates the possibility of non-compliance with these indicators in some areas of the weld. The index of efficiency of the welding process can be recommended for statistically substantiated choice of welding materials for a given product, which will reduce the risks of using unacceptable welding materials for a given product.