Strength Assessment of Welded Joints of High-Strength Alloy Steels by Indentation Method

The paper presents the indentation method for strength assessment of the welded joints in high-strength alloy steels, including base metal, heat-affected zone, and welded joint, in production after application of selected flaw detection methods as a final stage of non-destructive testing methods. Non-destructive testing methods are mainly used to detect defects, their location, size, and nature. The indentation method allows one to determine both the joint strength and the strength and dimensions of the heat-affected zone during the production process. The authors performed the comparative analysis on the hardness and strength limit of welded joints of 30Kh2CN2MFA and 28GRA alloy steels as delivered of sheet metal of 6 mm in thickness (for the production of special structures) to corroborate the method efficiency. It is shown that the Brinell hardness values obtained by the TSH-2 stationary hardness tester, ERNST Computest SC portable hardness tester, and instrumented indentation imply the same nature of the hardness distribution along the length of the specimen cut across the axis of the welded joint. The distribution nature of the strength limit values determined by the indentation method is similar to that of the Brinell HBW hardness distribution. It is established that the deviation of strength limit values determined by the indentation method did not exceed 3.7%.