High-strength low-temperature steel with high hydrogen induced cracking (HIC) and sulfide stress corrosion cracking (SSC) resistance and manufacturing method thereof

Abstract

The invention relates to high-strength low-temperature steel with high hydrogen induced cracking (HIC) and sulfide stress corrosion cracking (SSC) resistance and a manufacturing method thereof. A low alloy steel component system with ultra-low C content, low Si content, medium Mn content, low Als content, low N content, a little alloyed Ni and Mo and trace Ti and Nb is adopted, Mn/C is more than or equal to 22, the segregation index 1.32 (percent C)*[(1.53 (percent Mn)+1.37 (percent Si)+1.15 (percent Mo)+1.06 (percent Cr)+(percent Cu)+0.86 (percent Ni)]*[(30 (percent P)+10 (percent S)] is less than or equal to 0.060, [(percent Si)+(percent Als)]*(percent C) is less than or equal to 0.0035, Pcm is less than or equal to 0.018 percent, Nib/Ti is 1.5 to 3.5, Ca treatment is performed, Ca/S is 0.80 to 3.00, the microstructure of a finished steel plate product consists of uniform and fine acicular ferrites and a few upper bainites by optimizing a thermal mechanical control processing (TMCP) technology, and the average particle size is less than 10mu m; and the characteristics of high strength, toughness and HIC and SSC resistance are achieved, high heat input welding can be performed, and the steel is particularly suitable for manufacturing a low temperature storage tank, a low temperature pressure steel pipe, an ocean platform in an ice sea area, and the like.

Description

technical field [0001] The present invention relates to low-carbon high-strength low-alloy steel, in particular to a high-strength low-temperature steel with excellent resistance to HIC and SSC and its manufacturing method, which is an ultra-low C-low Si-medium Mn-low Als-low N- A small amount of (Ni+Mo) alloyed - micro (Ti+Nb) treated low-alloy steel, yield strength ≥ 460MPa, tensile strength ≥ 550MPa, Charpy transverse impact energy (single value) ≥ 47J at -50°C, can be welded with large heat input, resistant HIC and SSC low-temperature TMCP steel plates are mainly used for low-temperature storage tanks, low-temperature pressure steel pipes, offshore platforms in ice sea areas and UOE manufacturing materials. 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 pressure vessels, ...

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Problems solved by technology

[0004] In the prior art, when producing thick steel plates with yield strength ≥ 415MPa and low-temperature impact toughness ≥ 34J at -60°C, a certain amount of Ni or Cu+Ni elements are generally added to the steel to ensure that the base steel plate has excellent low-temperature toughness. ≤100KJ / cm of heat welding, the toughness of the heat-affected zone HAZ can also reach -60 ℃ Akv≥34J, but not involved in the H 2 How steel plates resist hydrogen-induced cracking HIC and sulfide stress corrosion cracking SSC characteristics in S-corrosion environment

[0005] A large number of existing patent documents only explain how to realize the low-temperature toughness of the base metal steel plate. There are few explanations on how to obtain excellent low-temperature toughness of the heat-affected zone (HAZ) under welding conditions, especially how to ensure the heat-affected toughness when welding with large input energy. The low-temperature toughness of the steel plate (HAZ) is very little, and in order to ensure the low-temperature toughness of the steel plate, a certain amount of Ni or Cu+Ni elements are generally added to the steel, and the low-temperature toughness of the heat-affected zone (HAZ) of the steel plate is rarely able to reach -60°C

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