High-aluminum-content fine-grain low-density full-high-temperature ferrite steel and preparation method thereof

Abstract

The invention provides a high-aluminum-content fine-grain low-density full-high-temperature ferrite medium-thickness plate for an ocean platform and a preparation method for the high-aluminum-contentfine-grain low-density full-high-temperature ferrite medium-thickness plate. The steel is prepared from the following chemical components in percentage by mass: 0.01-0.039 percent of C, 4.01-6.00 percent of Al, 0.01-1.40 percent of Mn, 0.01-2.00 percent of Cr, 0.002-0.003 percent of B, 0.02-0.06 percent of Ti, 0.01-0.39 percent of Ni, less than or equal to 0.007 percent of Nb, less than or equal to 0.015 percent of P, less than or equal to 0.005 percent of S and the balance of Fe and other inevitable impurities. For the high-aluminum-content fine-grain low-density full-high-temperature ferritemedium-thickness plate and preparation method thereof, by controlling the components and a structure, the corrosion resistance in a marine atmospheric environment is better than that of currently commonly used weathering steel Corten-A by 70 percent or above, and the average grain size of the steel is refined to 50 microns or below.

Description

technical field [0001] The invention belongs to the field of metal materials, in particular to a method for preparing high-aluminum-content fine-grained low-density full-temperature ferritic steel for offshore platforms. Background technique [0002] With the continuous development of the marine economy, the demand for steel for offshore platforms is also showing a gradual increase. Due to the extremely complex marine environment, it has to withstand the erosion and damage of natural forces such as waves, earthquakes in Haiti, and low temperature. Marine engineering equipment serves in severe marine environments and must withstand severe loads and complex corrosion environments. From the perspective of energy saving and emission reduction and the structural safety of offshore platforms, there is a demand for weight reduction in steel for offshore engineering. Adding Al to steel reduces the density and improves the corrosion resistance of the steel plate. Therefore, the addi...

AI Technical Summary

Problems solved by technology

The alloy composition provided in this patent CN110066969B, the content of Ni, Mo, and Nb elements in the composition system is relatively high. This patent mainly uses Mo solid solution in δ ferrite to improve pitting resistance and intergranular corrosion resistance. Ni is dissolved in δ ferrite to improve corrosion resistance, but Ni and Mo elements are more expensive alloy elements, and the cost is higher

This patent uses Nb to inhibit grain growth and refine δ ferrite grains, but Nb also has the effect of inhibiting recrystallization, so it can be predicted that Nb has limited effect on δ ferrite grain refinement, and at the same time, the cost of Nb element is relatively high

This patent uses rare earth elements to refine δ ferrite grains and improve corrosion resistance, but the cost of rare earth elements is also high, and the smelting process is extremely difficult to control

In addition, the rolling process provided by this patent is complicated, the rolling direction needs to be changed during the rolling process, the demand for equipment is high, and the original size of the slab and the final size of the plate are also limited

Therefore, the preparation process of this patent is complex, there are many technical problems that are not conducive to industrial production and application, and the cost is relatively high

[0004] Patent Nos. CN103484771B and CN106498278 both disclose the preparation method of non-full delta ferritic low-density steel. The final structure is a multi-phase structure. Due to the different alloy content of each phase of the multi-phase structure, galvanic couples will occur during the corrosion process. Corrosion, corrosion resistance is much lower than single-phase microstructure

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