A kind of industrial stable high-performance bolt steel and its manufacturing method

Abstract

The invention discloses industrial stable high-performance bolt steel and a manufacturing method thereof and belongs to the technical field of high-strength bolt steel. The chemical components of the steel comprise, by mass, 0.28-0.37% of C, equal to or less than 0.10% of Si, 0.15-0.30% of Mn, equal to or less than 0.010% of P, equal to or less than 0.005% of S, 1.10-1.20% of Cr, 0.15-0.40% of Mo, 0.0005-0.003% of B, 0.03-0.08% of Ti, 0.015-0.030% of Al and equal to or less than 0.005% of N, and the balance is Fe, on the basis, 0.15-0.30% of V or 0.02-0.04% of Nb can be added. Through the adoption of a reasonable controlled rolling and controlled cooling technology, the original austenite grain size of the steel after phase change is further refined by 1-2 grades, 3-8 um superfine austenite grains and precipitated phase with the size of 1-20 nm are obtained, and therefore the high-temperature tempering strength of the steel is improved. The industrial stable high-performance bolt steel and the manufacturing method thereof have the advantages that compared with the prior art, the carbon content of the steel in the same strength grade is reduced, the hardness fluctuation after quenching+tempering is small, the strength after high-temperature tempering is high, the stability of batch quality is high, the cost is low, and the delayed fracture resistance is excellent.

Description

technical field [0001] The invention belongs to the technical field of steel for high-strength bolts, and in particular provides an industrially stable high-performance steel for bolts and a manufacturing method thereof. It is mainly used for the manufacture of high-strength bolts with tensile strength between 1040-1450MPa and delayed fracture resistance of grade 10.9-14.9. By obtaining precipitated nanoscale strengthening phase and ultra-fine grain structure, precipitation strengthening replaces partial solid solution strengthening, and improves the plasticity of bolts. Toughness level and hydrogen-induced delayed fracture performance, and improved cold heading performance and batch hardness uniformity and stable performance after tempering. Background technique [0002] With the development of energy, automobile, machinery, construction, light industry and other industries, higher requirements are put forward for the materials used in the manufacture of various fastening b...

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Problems solved by technology

At present, there is no technology that considers the quality stability of bolt steel from the design of material alloy element composition and the manufacturing method to realize this design.

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