Статична тріщиностійкість зварних з’єднань магнієвого сплаву МА2-1М , отриманих неплавким електродом і тертям із перемішуванням

Magnesium alloys are considered promising materials for use in aerospace and automotive engineering. However, their increased sensitivity to stress concentrators can adversely affect the material’s performance during operation. Therefore, it is essential to assess their resistance to crack initiation and propagation under conditions simulating actual operation, based on the principles of experimental fracture mechanics. This work aims to evaluate the resistance to crack initiation and propagation in different structural zones of welded joints in the MA2-1M magnesium alloy, produced using tungsten inert gas welding and friction stir welding technologies. The resistance to failure under eccentric tensile loading of MA2-1M magnesium alloy welded joints, 2 mm in thickness and produced by argon arc welding with a non-consumable electrode (TIG) and by friction stir welding (FSW), was determined. The testing configuration replicated the stress state of welded structural joints and complied with the technical requirements of ASTM E561-98. It has been shown that under combined tension and bending, the strength of joints welded using a non-consumable electrode is determined by the presence of technological reinforcement and ranges from 167 to 223 MPa, while in the fusion zone it ranges from 175 to 192 MPa. For friction stir welding, the strength level of the joints is determined by the rotational speed of the welding tool (8–24 m/h) and ranges from 178 to 207 MPa, with values in the heat-affected zone (HAZ) ranging from 115 to 253 MPa. It has been established that the FSW process, regardless of the welding speed, provides greater stability of MA2-1M joints in terms of both crack initiation and propagation. The values of specific crack initiation work (SCIW) and specific crack propagation work (SCPW) for joints obtained by TIG welding are halved when the reinforcement is mechanically removed. The resistance of welded joints of MA2-1M magnesium alloy has been determined for the first time. It has been found that the sensitivity of these welded joints to sharp notches does not depend on the welding method.