A FH36 marine steel with excellent resistance to hydrogen-induced cracking and its manufacturing method

Abstract

This invention discloses an FH36 marine engineering steel with excellent resistance to hydrogen-induced cracking and its manufacturing method, belonging to the field of steel material preparation technology. The chemical composition and mass percentage of the FH36 marine engineering steel of this invention are as follows: C: 0.05%–0.10%; Si: 0.10%–0.35%; Mn: 0.90%–1.20%; P: ≤0.012%; S ≤0.002%; Cu: 0.15%–0.40%; Ni: 0.30%–0.60%; Cr: 0.10%–0.20%; Nb: 0.02%–0.045%; V: 0.03%–0.05%; Ti: 0.007%–0.02%; Alt: 0.01%–0. 0.3%; O≤0.001%; ​​N≤0.005%, balance being Fe and unavoidable impurities, Ceq≤0.38%, solving the problem of difficult matching and harmonizing the strength, plasticity, low-temperature toughness (-60℃) and hydrogen-induced cracking resistance of FH36 steel plate. The produced steel plate has a yield strength ≥355MPa, tensile strength 490~630MPa, elongation at section ≥21%, Z-direction reduction of area ≥65%, Charpy impact energy of the steel plate core at -60℃ ≥100J, and hydrogen-induced cracking resistance CSR≤2%, CLR≤15%, CTR≤5%.

Description

Technical Field

[0001] This invention belongs to the field of steel material preparation technology, specifically relating to an FH36 marine steel with excellent resistance to hydrogen-induced cracking and its manufacturing method. Background Technology

[0002] Steel, as a key structural material for marine engineering equipment, is widely used in offshore wind power, production platforms, and subsea pipelines. Marine engineering equipment typically has a service life of 30 years, 50% longer than traditional ships. The operating environment of marine engineering equipment is extremely harsh, subject not only to its own weight but also to the effects of service conditions. This necessitates that marine engineering steel designs and material selections consider specific sea conditions. How to simultaneously achieve ultra-high strength, high toughness, and high resistance to hydrogen-induced cracking has become a core issue and technical challenge in the development of deep-sea engineering steel. To ensure the safe operation of marine engineering platforms in complex environments, there is an urgent need to develop high-strength marine engineering steel with excellent resistance to hydrogen-induced cracking.

[0003] Patent CN111492083B, entitled "High-strength steel with excellent resistance to hydrogen-induced cracking and low-temperature impact toughness and its manufacturing method," provides a high-strength steel with excellent resistance to hydrogen-induced cracking and low-temperature impact toughness and its manufacturing method, employing a TMCP + normalizing production process. However, its yield strength cannot be guaranteed to reach 355 MPa, failing to meet the high-strength requirements of marine engineering steel. Patent CN106521332A, entitled "A steel plate resistant to stress-directed hydrogen-induced cracking and its manufacturing method," proposes a steel plate resistant to stress-directed hydrogen-induced cracking, characterized by high purity, excellent low-temperature impact toughness at -20℃, excellent resistance to lamellar tearing, and excellent resistance to stress-directed hydrogen-induced cracking. However, it cannot guarantee low-temperature toughness at -60℃. The patent with publication number CN105803327B, entitled "An economical HIC-resistant X90 pipeline steel plate and its manufacturing method", proposes an X90-level pipeline steel plate, an HIC-resistant steel with a maximum thickness of 20mm and its manufacturing method. However, its thickness is relatively small and cannot meet the large thickness requirements of ultra-high strength marine engineering steel for marine engineering platform equipment.

[0004] The patent comparison above shows that the marine steels currently available with excellent resistance to hydrogen-induced cracking have the following shortcomings: 1. The product thickness is relatively small, the strength level is relatively low, and the application range is narrow; 2. The product has a low ultra-low temperature toughness level, which cannot meet the requirements of marine steel to have both high strength and high toughness. Summary of the Invention

[0005] To address the problems existing in the background technology, the purpose of this invention is to provide an FH36 marine engineering steel with excellent resistance to hydrogen-induced cracking and its manufacturing method. This invention, through optimized alloy content design and a coupled design of smelting-controlled rolling-controlled cooling processes, ultimately obtains an FH36 marine engineering steel with excellent resistance to hydrogen-induced cracking up to 60 mm thick. The steel plate of this invention possesses high strength (yield strength ≥355 MPa, tensile strength 490~630 MPa, elongation after fracture ≥21%), excellent low-temperature toughness (impact absorption energy at -60℃ ≥100 J), excellent Z-direction reduction of area (≥60%), excellent resistance to hydrogen-induced cracking (CSR≤2%, CLR≤15%, CTR≤5%), and uniform microstructure and properties.

[0006] The objective of this invention is achieved through the following means:

[0007] This invention provides an FH36 marine engineering steel with excellent resistance to hydrogen-induced cracking. The chemical composition and mass percentage of the FH36 marine engineering steel are as follows: C: 0.05%~0.10%; Si: 0.10%~0.35%; Mn: 0.90%~1.20%; P: ≤0.012%; S≤0.002%; Cu: 0.15%~0.40%; Ni: 0.30%~0.60%; Cr: 0.1 0%~0.20%; Nb: 0.02%~0.045%; V: 0.03~0.05%; Ti: 0.007%~0.02%; Alt: 0.01%~0.03%; O≤0.001%; ​​N≤0.005%, with the balance being Fe and unavoidable impurities, Ceq≤0.38%, where Ceq=C+Mn / 6+(Cu+Ni) / 15+(Cr+Mo+V) / 5.

[0008] The mechanisms of action of each alloy component in the FH36 marine steel of this invention are as follows:

[0009] Carbon (C) is an essential element for ensuring strength and hardenability. It plays a significant role in improving the strength of steel through solid solution strengthening and precipitation strengthening. However, an increase in carbon content seriously affects the weldability and low-temperature toughness of steel. From the perspective of product performance, it is preferable to control the C content between 0.05% and 0.10%.

[0010] Si is a solid solution strengthening element and also the main deoxidizing component in the steelmaking process. In order to obtain a sufficient deoxidation effect, it must contain more than 0.10%. However, if the content is too high, it will seriously damage the low-temperature toughness, elongation and weldability of ultra-high strength steel plates. Considering the economy and operability of steelmaking, the preferred Si content is 0.10% to 0.35%.

[0011] Mn: As the most important alloying element in steel, in addition to improving the strength of steel plates, it also has the functions of expanding the austenite phase region, lowering the Ar3 point temperature, refining ferrite grains, and improving the low-temperature toughness of steel plates. However, when the quality of Mn is too high, Mn segregation and strip-shaped MnS are easily formed, which makes the low-temperature toughness and resistance to hydrogen-induced cracking in the core of the thick plate poor, and the performance of the weld heat-affected zone decreases. Therefore, the preferred Mn content range is 0.90% to 1.20%.

[0012] P: is an element that has an adverse effect on the impact value. It can impair low-temperature toughness by segregating in the center of the slab and agglomerating at grain boundaries. The material content of this invention is controlled to be no higher than 0.012%.

[0013] S: is an element that has an adverse effect on the impact value and can form sulfide inclusions, which can become crack initiation sites. The material in this invention is controlled to be no higher than 0.002%.

[0014] Cu: ε-Cu precipitation strengthening can significantly improve the strength of steel; appropriate amounts of Cu can increase strength without compromising impact toughness. Cu is also an austenite-forming element, expanding the austenite phase region while promoting austenite formation and stability during tempering. Cu precipitates can increase the density of effective hydrogen traps, resulting in smaller hydrogen-induced cracks. When used in conjunction with Ni, it can not only significantly reduce Ar3 but also prevent hot brittleness. However, excessive Cu content can cause hot brittleness, which is detrimental to the toughness of the base material and the heat-affected zone. Therefore, the Cu content in this invention ranges from 0.15% to 0.40%.

[0015] Ni: Nickel dissolves in austenite, inhibiting austenite recrystallization, refining austenite grains, and improving the low-temperature toughness of steel plates. Ni can reduce the diffusion rate of various elements in steel, thus delaying the decomposition and transformation of austenite, thereby improving the hardenability of steel. However, excessive Ni content will increase Ceq, affecting weldability; therefore, the Ni content in this invention is controlled at 0.30%–0.60%.

[0016] Cr: It can improve the hardenability and strength of steel plates. Cr can also inhibit the transformation of proeutectoid ferrite and pearlite, which is beneficial to obtaining acicular ferrite structure. Cr has a similar solid solution strengthening effect to Mn and is less prone to segregation. However, if the Cr content is too high, it will increase the tendency for temper brittleness and increase the difficulty of welding, while if the content is too low, it cannot effectively exert its strengthening effect. In this invention, the Cr content is controlled at 0.10% to 0.20%.

[0017] Niobium (Nb) is added to promote grain refinement of the steel rolling microstructure, simultaneously improving strength and toughness. During controlled rolling, niobium effectively refines the microstructure by inhibiting austenite recrystallization and strengthens the matrix through precipitation. Simultaneously, the presence of Nb precipitates increases the density of effective hydrogen traps, resulting in smaller hydrogen-induced cracks. However, when the Nb content exceeds a certain range, MA islands will form in the welded HAZ, which is detrimental to toughness. In this invention, the Nb content is preferably controlled between 0.02% and 0.045%.

[0018] V: Adding V to steel can refine the grain structure, improve strength and toughness, and enhance the steel plate's resistance to tempering softening during tempering. Too little V will have little effect; too much V will reduce the steel's toughness and weldability. With an appropriate nitrogen content, V can fully precipitate, significantly reducing the particle size and spacing in the steel, resulting in precipitation strengthening and thus improving strength. Therefore, this invention controls the V content to be between 0.03% and 0.05%.

[0019] Ti: Ti, when present in trace amounts, forms nitrides, carbides, or carbonitrides, which can refine grains and improve the toughness of the base material. However, when the Ti content is too high, excess Ti easily precipitates as TiC on bainitic laths and grain boundaries, severely degrading the low-temperature toughness of the steel plate. Therefore, in this invention, the Ti content is controlled at 0.007% to 0.02%.

[0020] Alt (Al): A deoxidizing and grain-refining element. At high temperatures, Al forms fine AlN precipitates, which inhibit austenite grain growth during the austenitization process of slabs / steel plates, thus refining the austenite grains and improving the toughness of the steel at low temperatures. Excessive Al content leads to the formation of larger Al oxides, reducing the low-temperature impact resistance of the steel plate. Additionally, it makes the slab prone to edge and corner cracks during continuous casting. The preferred Alt content is controlled between 0.01% and 0.03%.

[0021] O: An element that has an adverse effect on impact toughness. It combines with other elements in steel to form non-metallic inclusions, which become crack initiation sites. In this invention, the O content is controlled to be no higher than 0.001%.

[0022] N: N element will form coarse ALN with AL and precipitate along the original austenite grain boundary, affecting the hardenability and low temperature impact toughness of steel. In this invention, the N content is controlled to be no higher than 0.005%.

[0023] Based on the above technical solution, the FH36 marine steel further has a yield strength ≥355MPa, tensile strength 490~630MPa, elongation at section ≥21%, Z-direction reduction of area ≥65%, Charpy impact energy of steel plate core at -60℃ ≥100J, and resistance to hydrogen-induced cracking CSR≤2%, CLR≤15%, and CTR≤5%.

[0024] The present invention also provides a method for manufacturing the above-mentioned FH36 marine steel with excellent resistance to hydrogen-induced cracking, which mainly includes the following steps: smelting step → continuous casting and billet slow cooling step → rolling step → rapid cooling step → slow cooling step.

[0025] Based on the above technical solution, further, the molten iron is desulfurized before the smelting process, and the smelting process includes converter smelting, ladle refining and vacuum treatment.

[0026] Based on the above technical solution, further, in the continuous casting and billet slow cooling process, the superheat of the molten steel in the ladle is 25-30℃, the casting is protected throughout the process, the light reduction is 6-9mm, the thickness of the continuous casting billet is 250-300mm, the continuous casting billet is stacked and slow cooled after leaving the line, the stacking temperature is ≥650℃, and the stacking slow cooling rate is 5-6℃ / h.

[0027] Based on the above technical solution, furthermore, in the rolling process, the continuously cast billet adopts a 4-stage heating process, namely a preheating stage, heating stage 1, heating stage 2, and soaking stage. The heating temperature of the preheating stage is 750-820℃, the heating temperature of heating stage 1 is 900-1080℃, the heating temperature of heating stage 2 is 1130-1180℃, the heating temperature of the soaking stage is 1080-1130℃, the heating time of the preheating stage is 0.1-0.2 min / mm, the heating time of heating stage 1 is 0.2-0.4 min / mm, the heating time of heating stage 2 is 0.1-0.3 min / mm, and the heating time of the soaking stage is 0.3-0.5 min / mm.

[0028] The rolling process is carried out in two stages. The first stage rolling temperature is 950-1000℃, and the single-pass reduction rate is ≥15% except for the widening pass. The thickness of the intermediate billet is ≥2 times the thickness of the finished product. The intermediate billet is water-cooled with a cooling rate of ≥2℃ / s. The second stage rolling temperature is 760-820℃, the single-pass reduction rate is ≥11%, and the final rolling temperature is 720-790℃.

[0029] Based on the above technical solution, the billet is further subjected to high-pressure water descaling 1 to 5 times after being heated and tapped out of the furnace, which removes the iron oxide scale on the surface and reduces the temperature of the continuous casting billet.

[0030] Based on the above technical solution, the final rolled steel plate directly enters the rapid cooling process, with an average cooling rate of ≥5℃ / s and a reddening temperature of 480~550℃.

[0031] Based on the above technical solution, the rapid cooling process further adopts the DQ+ACC rapid cooling system.

[0032] Based on the above technical solution, further, in the slow cooling process, the temperature of the tank entering the tank is not lower than 350℃, and the slow cooling time is not less than 24 hours.

[0033] The advantages of this invention over the prior art are as follows:

[0034] (1) This invention manufactures marine engineering steel with good comprehensive mechanical properties through alloy composition design-smelting, continuous casting-controlled rolling-controlled cooling process coupling design. It solves the problem of difficulty in matching and harmonizing the strength, plasticity, low temperature toughness (-60℃) and resistance to hydrogen-induced cracking of FH36 steel plate. The produced steel plate has a yield strength ≥355MPa, tensile strength 490~630MPa, elongation at section ≥21%, Z-direction reduction of area ≥65%, Charpy impact energy of steel plate core at -60℃ ≥100J, and resistance to hydrogen-induced cracking CSR≤2%, CLR≤15%, and CTR≤5%.

[0035] (2) This invention fully leverages the technical equipment advantages of the heavy plate rolling mill and heat treatment unit, and combines 250-300mm thick continuous casting slabs to develop ultra-high strength and high toughness marine engineering steel thick plates with a maximum thickness of 60mm.

[0036] (3) The microstructure of the steel plate is a mixture of bainite, ferrite and a small amount of pearlite. Attached Figure Description

[0037] To more clearly illustrate the embodiments of the present invention, the accompanying drawings involved in the embodiments will be briefly described below.

[0038] Figure 1 Metallographic image (200x magnification) of the marine steel prepared in Example 2. Detailed Implementation

[0039] The present invention will be described in detail below with reference to the embodiments. However, the implementation of the present invention is not limited thereto. Obviously, the embodiments described below are only some embodiments of the present invention. For those skilled in the art, other similar embodiments can be obtained without creative effort and all fall within the protection scope of the present invention.

[0040] Examples 1-13

[0041] This embodiment provides a method for preparing FH36 marine engineering steel with excellent resistance to hydrogen-induced cracking. The chemical composition and weight percentage of the marine engineering steel in this embodiment are shown in Table 1:

[0042] Table 1 shows the chemical composition and weight percentage (wt%) of FH36 marine steel in the examples.

[0043] Example C Si Mn P S Cu Ni Cr Nb V Ti Alt O N Ceq 1 0.071 0.25 1.19 0.008 0.002 0.26 0.48 0.19 0.041 0.041 0.014 0.016 0.0009 0.0031 0.365 2 0.066 0.31 1.09 0.007 0.002 0.22 0.51 0.15 0.039 0.046 0.012 0.018 0.0008 0.0024 0.336 3 0.081 0.17 0.99 0.01 0.001 0.19 0.41 0.18 0.031 0.039 0.016 0.024 0.001 0.0033 0.330 4 0.094 0.14 0.91 0.009 0.002 0.22 0.46 0.17 0.036 0.036 0.013 0.019 0.0007 0.0035 0.332 5 0.061 0.16 1.17 0.011 0.002 0.34 0.55 0.14 0.029 0.049 0.010 0.014 0.0008 0.0042 0.353 6 0.079 0.26 1.08 0.008 0.001 0.16 0.38 0.13 0.024 0.044 0.009 0.021 0.0009 0.0041 0.330 7 0.069 0.21 1.16 0.009 0.002 0.29 0.44 0.18 0.034 0.032 0.008 0.025 0.0007 0.0034 0.353 8 0.087 0.19 1.01 0.012 0.002 0.18 0.36 0.16 0.026 0.031 0.009 0.019 0.0009 0.0028 0.330 9 0.074 0.29 0.96 0.008 0.001 0.28 0.31 0.19 0.021 0.038 0.017 0.023 0.0007 0.0035 0.319 10 0.079 0.16 0.97 0.007 0.001 0.23 0.47 0.11 0.037 0.034 0.011 0.018 0.0007 0.0033 0.316 11 0.055 0.33 0.98 0.008 0.002 0.35 0.55 0.18 0.042 0.041 0.016 0.014 0.0008 0.0032 0.323 12 0.091 0.15 1.09 0.006 0.002 0.17 0.51 0.15 0.031 0.042 0.015 0.018 0.0009 0.0041 0.356 13 0.078 0.19 0.99 0.009 0.001 0.31 0.41 0.16 0.024 0.033 0.012 0.024 0.0007 0.0043 0.330

[0044] Includes the following steps:

[0045] 1) Smelting, continuous casting and slow cooling of billet: The production process is carried out by deep desulfurization of molten iron, converter smelting, ladle refining, vacuum treatment and continuous casting. The superheat of molten steel in the tundish is shown in Table 2. The casting process is protected throughout, and electromagnetic stirring is turned on and combined with a light reduction process. The amount of light reduction is shown in Table 2. After continuous casting, a continuous casting billet is obtained with a thickness of 250-300 mm. After the continuous casting billet is removed from the line, it is stacked and slow cooled. The stacking temperature and stacking slow cooling rate are shown in Table 2.

[0046] Table 2 shows the continuous casting and billet slow cooling stacking process parameters for FH36 marine steel in the embodiments.

[0047]

[0048] 2) Rolling process: The continuously cast billet is heated in 4 stages, namely the preheating stage, heating stage 1, heating stage 2, and soaking stage. The heating temperature and time of the preheating stage, heating stage 1, heating stage 2, and soaking stage are shown in Table 3. After the billet exits the furnace, it is descaled with high-pressure water 2-3 times to remove the surface iron oxide scale and reduce the temperature of the continuously cast billet. Two-stage rolling is adopted. The starting rolling temperature, minimum single-pass reduction rate (except for the widening pass), and intermediate billet thickness of the first stage are shown in Table 4 to improve the as-cast structure of the slab, reduce the billet thickness waiting for heating, and shorten the waiting time of the steel plate. The thickness of the intermediate billet is twice the thickness of the finished product. The intermediate billet is water-cooled, and the cooling rate is shown in Table 4. The starting rolling temperature, minimum single-pass reduction rate, and final rolling temperature of the second stage are shown in Table 4. The first stage of rolling fully realizes the recrystallization of austenite at the 1 / 4 and 1 / 2 thickness positions of the steel plate, while avoiding the growth of austenite grains after recrystallization. The second stage introduces strain at 30-50℃ below Ar3, which promotes the generation of a large number of ferrite nucleation particles in the austenite grains. The microstructure after the phase transformation consists of low-carbon bainitic ferrite grains, ultrafine ferrite, or a small amount of pearlite or MA, and is significantly refined. These refined grains have large-angle grain boundaries, which increases the length of the crack propagation path, improves the fracture resistance and energy dissipation of the material, and thus enhances the crack arrest ability of the material.

[0049] 3) Cooling process: The steel plate is directly cooled after final rolling using the DQ+ACC rapid cooling system. The average cooling rate and reddening temperature are shown in Table 4. The microstructure is controlled by controlling the post-rolling cooling.

[0050] Table 3 shows the slab heating process parameters for FH36 marine steel in the embodiments.

[0051]

[0052] Table 4 shows the rolling and cooling process parameters of FH36 marine steel in the examples.

[0053]

[0054] 4) Slow cooling process: After cooling, the steel plate is immediately placed in a slow cooling tank with an inlet temperature of not less than 350℃ and a slow cooling time of not less than 24 hours to obtain the finished steel plate. The mechanical properties and hydrogen-induced cracking resistance of the finished steel plate are shown in Table 5-6.

[0055] Table 5 shows the mechanical properties of FH36 marine steel in the examples.

[0056]

[0057] Table 6 shows the hydrogen-induced cracking resistance of FH36 marine steel in the examples.

[0058]

[0059] Note: The solution used was NACEA, which, according to relevant standards, consisted of 5% NaCl + 0.5% CH3COOH + saturated H2S aqueous solution and was continuously soaked for 96 hours.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An FH36 marine steel with excellent resistance to hydrogen-induced cracking, characterized in that, The chemical composition and mass percentage of the FH36 marine engineering steel are as follows: C: 0.071%~0.10%; Si: 0.10%~0.35%; Mn: 0.90%~0.99%; P: ≤0.012%; S≤0.002%; Cu: 0.28%~0.40%; Ni: 0.31%~0.60%; Cr: 0.10%~0.20%; Nb: 0.02%~0.045%; V：0.03~0.05%； Ti: 0.007%~0.02%; Alt: 0.01%~0.03%; O≤0.001%; ​​N≤0.005%, balance is Fe and unavoidable impurities, Ceq≤0.38%, where Ceq=C+Mn / 6+(Cu+Ni) / 15+(Cr+Mo+V) / 5; The FH36 marine steel has a yield strength ≥355MPa, tensile strength 490~630MPa, elongation at section ≥21%, Z-direction reduction of area ≥65%, Charpy impact energy of the steel plate core at -60℃ ≥100J, and resistance to hydrogen-induced cracking CSR≤2%, CLR≤15%, and CTR≤5%. The microstructure of the FH36 marine steel plate is a mixed structure of bainite, ferrite, and a small amount of pearlite; the thickness is 45~60mm. The manufacturing method of the FH36 marine steel with excellent resistance to hydrogen-induced cracking mainly includes the following steps: smelting process → continuous casting and billet slow cooling process → rolling process → rapid cooling process → slow cooling process; In the rolling process, the continuously cast billet is heated in four stages: preheating stage, heating stage 1, heating stage 2, and soaking stage. The heating temperature of the preheating stage is 750-820℃, the heating temperature of heating stage 1 is 900-1080℃, the heating temperature of heating stage 2 is 1130-1180℃, and the heating temperature of the soaking stage is 1080-1130℃. The heating time of the preheating stage is 0.1-0.2 min / mm, the heating time of heating stage 1 is 0.2-0.4 min / mm, the heating time of heating stage 2 is 0.1-0.3 min / mm, and the heating time of the soaking stage is 0.3-0.5 min / mm. The rolling process is carried out in two stages. The first stage rolling temperature is 950-980℃, and the single-pass reduction rate is ≥15% except for the widening pass. The thickness of the intermediate billet is ≥2 times the thickness of the finished product. The intermediate billet is water-cooled with a cooling rate of ≥2℃ / s. The second stage rolling temperature is 760-820℃, the single-pass reduction rate is ≥11%, and the final rolling temperature is 720-790℃. In the continuous casting and billet slow cooling process, the superheat of molten steel in the tundish is 25~30℃, the casting is protected throughout the process, the light reduction is 6~9mm, the thickness of the continuous casting billet is 250~300mm, the continuous casting billet is stacked and slow cooled after it leaves the line, the stacking temperature is ≥650℃, and the stacking slow cooling rate is 5~6℃ / h. The steel plate after final rolling directly enters the rapid cooling process, with an average cooling rate of ≥5℃ / s and a reddening temperature of 480~550℃. The rapid cooling process uses the DQ+ACC rapid cooling system; During the slow cooling process, the temperature of the tank entering the tank shall not be lower than 350℃, and the slow cooling time shall not be less than 24 hours.

2. The FH36 marine steel with excellent resistance to hydrogen-induced cracking as described in claim 1, characterized in that, The molten iron undergoes deep desulfurization before the smelting process, which includes converter smelting, ladle refining, and vacuum treatment.

3. The FH36 marine steel with excellent resistance to hydrogen-induced cracking as described in claim 1, characterized in that, After being heated and tapped from the furnace, the billet is descaled by high-pressure water for 1 to 5 times to remove the surface iron oxide scale and reduce the temperature of the continuously cast billet.

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