Low-cost high-machinability steel for engineering machine and manufacturing method of steel

Abstract

The invention discloses low-cost high-machinability steel for an engineering machine and a manufacturing method of steel. The steel comprises components including, by weight, 0.06% to 0.10% of C, 0.30% to 0.60% of Si, 1.00% to 1.60% of Mn, not larger than 0.015% of P, not larger than 0.0030% of S, 0.20% to 0.60% of Ni, 0.50% to 0.80% of Cr, 0.25% to 0.55% of Mo, 0.025% to 0.065% of V, 0.0008% to 0.0020% of B, 0.008% to 0.018% of Ti, 0.030% to 0.070% of Al, not larger than 0.0050% of N, 0.0010% to 0.0040% of Ca, and the balance Fe and inevitable impurities. Mn / C is larger than 15, {steel plate quenching temperature*[(%Cr)+3.3(%Mo)+1.75(%V)+2.15(%Si)]} / [11.7(%C)<1 / 2>+1.23(%Mn)+0.36(%Cu)+(%Ni)] is larger than or equal to 415 and smaller than or equal to 565, Ca / S ranges from 0.80 to 1.50, and (%Ca)*(%S) is larger than or equal to 2.5*10<-6> and smaller than or equal to 2.5*10<-3>. Controlled rolling and two-phase-area quenching and tempering technologies are combined, high strength is obtained, and meanwhile, low-temperature toughness, cold machining moldability, welding performance and fatigue-resisting impact load properties of a steel plate are also excellent.

Description

technical field [0001] The invention belongs to the field of steel for engineering machinery, and in particular relates to a low-cost, high-machinability steel for engineering machinery and a manufacturing method thereof. ℃ Charpy transverse impact energy (single value) ≥ 47J, elongation at break δ 5 ≥18%, high strength quenched and tempered steel plate for construction machinery with high cold bending properties, excellent weldability, and excellent cold machining formability. Background technique [0002] As we all know, low-carbon (high-strength) low-alloy steel is one of the most important engineering structural materials, widely used in oil and gas pipelines, offshore platforms, shipbuilding, bridge structures, boiler containers, building structures, automobile industry, railway transportation and engineering machinery manufacturing Among them; the performance of low-carbon (high-strength) low-alloy steel depends on its chemical composition and manufacturing process, a...

AI Technical Summary

Problems solved by technology

[0007] A large number of existing patents and technical documents only explain how to achieve the strength and low-temperature toughness of the base metal steel plate. There are few explanations for improving the weldability of the steel plate and obtaining excellent low-temperature toughness in the HAZ of the welding heat-affected zone, and they do not involve how to improve the tensile strength of the steel plate. At the same time, improving the delayed crack resistance of the steel plate does not point out how to prevent the surface (sub) surface layer of the ultra-high strength steel plate from being over-quenched.

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