A kind of yttrium-based rare earth low-alloy high-strength steel and its manufacturing method

Abstract

The invention discloses low-alloy high-strength steel with yttrium-based rare earth. The low-alloy high-strength steel with the yttrium-based rare earth comprises the following chemical ingredients in percentage by mass: 0.08-0.19% of C, 0.15-0.55% of Si, 1.20-1.70% of Mn, not greater than 0.040% of P, not greater than 0.040% of S, not greater than 0.040% of Nb, not greater than 0.18% of V, not greater than 0.020% of Ti, not greater than 0.40% of Ni, not greater than 0.30% of Cr, not greater than 0.30% of Cu, not greater than 0.08% of Mo, not greater than 0.050% of Alt, not greater than 0.012% of N, 0.002-0.003% of O, and balance iron Fe, rare earth and inevitable impurities, wherein the rare earth is the yttrium-based rare earth; the steel comprises the following dissolved solid matters: 0.004-0.010% of Y, and 0.014-0.025% of Ce, and the residues exist in the form of combining Y and Ce with O, Mg, Al and S in the steel to form small dispersed compound inclusions; the compound inclusion component contains, in percentage by mass, 25.40-70.10% of Y, and 3.25-19.15% of Ce; and a matrix structure of the steel is a fine ferrite and perlite structure. The low-alloy high-strength steel disclosed by the invention is improved by utilizing the yttrium-based rare earth for exerting the effects of purification, modification, microalloying and oxide metallurgy in the steel.

Description

technical field [0001] The invention relates to a low-alloy high-strength steel and its manufacturing technology, in particular to a yttrium-based rare earth low-alloy high-strength steel and its manufacturing method. Background technique [0002] Low-alloy high-strength steel usually refers to steel with Mn content of 1.20% to 1.80% and yield strength not less than 345MPa. This steel is widely used in engineering, shipbuilding, construction, and bridges. C and Mn in steel are the basic elements to ensure high strength. "Manganese Segregation of Low Manganese Steel" edited by Xu Zuyao, the first edition of Metallurgical Industry Press in October 1979, pointed out that "for steel with a certain carbon content, It is said that adding manganese will reduce the ferrite content and increase the pearlite content, which is consistent with the observations in the early years.". Page P30 points out, "For the as-cast structure of 0.315C-1.80Mn steel, the carbon concentration fluctu...

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Problems solved by technology

In addition, although the MnS inclusions in the steel can be improved by feeding calcium wire to modify the denaturation, the degree of improvement is limited. Because the MnS inclusions have good thermoplasticity, they also extend along the rolling direction and are distributed in strips during rolling. It also affects the properties of steel

In order to reduce the banded structure of steel, it can generally be achieved by controlling the cooling rate during solidification, optimizing the deformation system during rolling, and reasonably controlling the final rolling temperature and post-rolling cooling rate, but for the improvement of the banded structure in steel The degree is limited, affecting the qualified rate of steel performance

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