Structure and Properties of Weldable Precipitation-Hardening Steel Alloyed with Copper for High-Strength Pipeline Fittings.

The influence of heat treatment, simulating thermal cycles and welding in the process of manufacturing joint fittings on microstructure, strengthening phase precipitation, and mechanical properties of base metal and near-weld zone of fittings, made of low-carbon copper-containing steel, is studied. Rolled product specimens are produced under laboratory and industrial conditions. Heat treatment regimes are developed, and mechanical properties of pipeline fittings of strength class K60 (X70) after normalizing with tempering and strength class K65 (X80) after additional quenching before tempering combined with satisfactory impact strength and weldability are provided. [ABSTRACT FROM AUTHOR]