High strength super-martensitic stainless steel for oil and gas pipelines and preparation method thereof

Abstract

The invention relates to high strength super-martensitic stainless steel for oil and gas pipelines and a preparation method thereof. The super-martensitic stainless steel consists of the following chemical compositions in percentage by mass: 0.01 to 0.03 percent of C, 0.5 to 1 percent of Si, 0.2 to 2.0 percent of Mn, 11.0 to 17.0 percent of Cr, 5.0 to 8.0 percent of Ni, 0.5 to 3.5 percent of Mo, less than or equal to 0.015 percent of P, less than or equal to 0.035 percent of S, 0.02 to 0.08 percent of N, 0.02 to 0.5 percent of Nb, less than 0.1 percent of W, and the balance of Fe and inevitable impurities. The preparation method for the high strength super-martensitic stainless steel comprises process steps of: smelting; casting; forging or rolling; quenching; tempering and the like. The steel can be used as a material for deep well and ultra deep well oil and gas pipelines and a material for crude oil and gas conveying equipment.

Description

technical field [0001] The invention relates to the field of metal materials, in particular to super martensitic stainless steel. Background technique [0002] Oil and natural gas are national strategic resources. Especially with the acceleration of my country's industrialization process and the improvement of people's living standards, the corresponding demand for energy has also increased sharply. Energy shortage has become one of the main factors restricting the country's economic development. In order to alleviate the increasingly serious contradiction between oil and gas supply and demand in my country and to further expand oil and natural gas mining areas, my country has shifted the key oil and natural gas mining areas from the central and eastern regions to the west and ocean areas. However, the oil and gas production conditions in this type of area are quite different from those in the past. For example, most of the wells in Xinjiang are deep and ultra-deep wells (th...

AI Technical Summary

Problems solved by technology

[0003] Usually 410 or 420 martensitic stainless steel can meet the strength required by casing and tubing for general oil and gas wells, but it cannot reach the yield strength of not less than 759MPa required in deep wells and ultra-deep wells, and its toughness is low. Breakage often occurs in the cycle, causing accidents

In order to solve the above problems, an improved martensitic stainless steel has been proposed, which has certain improvements in mechanical strength and corrosion resistance, but satisfactory results have not yet been achieved.

Such as CN1255569C and CN1257994C need to add expensive titanium, rare earth elements, nickel content is also high, so the cost is relatively high

In CN1250761C, secondary tempering is adopted, which increases the complexity of heat treatment process

Adopt quenching+low temperature tempering in CN101078088 (200610046693.3), carry out the technology of stabilizing aging treatment, but need long time aging treatment, have increased industrialized production cycle

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