Northeastern University

Yong Tian

Zhaodong Wang

Tianliang Fu

Hao Wu

Guodong Wang

Xiangtao Deng

Yimin Wang

Bingxing Wang

Yong Li

Junyu Wu

Jiadong Li

Qibin Ye

Tian Zhang

Liye Kan

Cheng Zhou

Yi Han

Qinghai Wang

The present invention discloses a low-yield-ratio ultra-high-strength high-toughness steel for pressure hulls and a preparation method therefor, wherein the chemical components by weight percentage are: 0.05%-0.10% of C, 0.15%-0.35% of Si, 0.60%-1.00% of Mn, 0.10%-0.50% of Cu, 0.10%-1.00% of Mo, 0.40%-0.70% of Cr, 0.05%-0.15% of V, 5.00%-10.00% of Ni, and the balance of Fe and unavoidable impurities. The technical solution of the present invention adopts secondary quenching heat treatment, the first quenching is performed to achieve complete austenitizing, and then the second quenching and tempering are performed to finally obtain complex phase structures such as tempered martensite, critical ferrite and retained austenite, so as to meet the performance index requirements of low yield ratio, ultra-high strength and high toughness, and thereby promoting application in practice.

Low-yield-ratio ultra-high-strength high-toughness steel for pressure hulls and preparation method therefor

An ultrahigh-strength ultrahigh-toughness and low-density dual-phase lamellar steel plate is disclosed. The steel plate comprises the following alloy components in percentage by mass: 0.200-0.320% of C, 0.600-2.000% of Mn, 0.200-0.600% of Si, 2.000-4.000% of Al, 0.300-1.200% of Ni, 0.001-0.005% of B, P not greater than 0.012%, S not greater than 0.005%, and the balance of Fe and inevitable impurities. The steel plate consists of dual phases of ferrites and martensites, the ferrites are high-temperature delta ferrites, the martensites are lath martensites, the delta ferrites are distributed in the lath martensites in a lamellar mode. The steel plate has excellent mechanical properties, for example, the yield strength in the rolling direction is not less than 1000 MPa, the tensile strength is not less than 1600 MPa, the elongation is not less than 8.0%, and the average value of Charpy V-Notch impact energy at &#x2212;40&#xb0; C. is not less than 350J.

Ultrahigh-strength ultrahigh-toughness and low-density dual-phase lamellar steel plate and preparation method therefor

The present invention relates to controlled cooling in manufacture of steel plate, and in particular, to an on-line cooling system for controlled rolling with an inter-pass cooling process, which comprises a rolling mill and on-line cooling equipment. The cooling equipment is accessorily arranged on the exit of the rolling mill, so that the rolling mill and the cooling equipment are combined. One rolling mill and one set of on-line cooling equipment are considered a cooling group, and several such groups are connected in series, so the steel plate can be cooled in any rolling pass. In this invention, both the cooling system and the water supply system are arranged on the main frame, and the rolling process and the cooling process are synchronized by using inter-pass cooling. Consequently, satisfied rolling effect in the condition of a temperature gradient along the thickness direction, grain refinement at the surface and drastic strength improvement without sacrificing toughness are achieved. Besides, better quality of the plate center region is obtained, double bulging is avoided and the yield of steel plate is improved due to the higher deformation permeability.

Cooling method and on-line cooling system for controlled rolling with inter-pass cooling process

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Shenyang, China

Yong Tian