Influence of microalloying with boron on the structure and properties of high-strength oil pipe

Microalloying with boron (up to 0.005%) has a considerable influence on the hardenability of steel. Four alloying systems with complete and partial replacement of molybdenum by microadditions of boron are studied. The resulting mechanical properties are satisfactory for high-strength pipe corresponding to strength groups from N80 (type Q) to Q135, according to the API 5CT, ISO 11960, and GOST R 53366 standards. The reversible tempering brittleness of Nb-B steel and Mo-B steel is considered. Overall, the strength and impact strength of Mo-B steel are greater than for steel without molybdenum.