Steel for welding high-speed rail bogie and manufacturing method thereof

Abstract

The invention discloses steel for welding an iron bogie and a manufacturing method of the steel, and relates to the field of welding materials, and the steel for welding comprises the following components in percentage by weight: 0.04 to 0.08 percent of C, 0.45 to 0.60 percent of Si, 1.40 to 1.60 percent of Mn, less than or equal to 0.015 percent of P, 0.010 to 0.018 percent of S, 0.40 to 0.60 percent of Cr, 0.35 to 0.50 percent of Ni, 0.22 to 0.35 percent of Cu, 0.025 to 0.050 percent of Ti, less than or equal to 0.015 percent of Al, less than or equal to 0.012 percent of As, Sn and Pb, and the balance of Fe and inevitable impurity elements. The manufacturing method sequentially comprises the following steps: carrying out primary smelting; performing LF refining; performing RH refining; continuous casting; rolling the wire rod; and carrying out online destressing treatment. According to the invention, deposited metal based on a welding wire made of steel for welding can meet high strength and excellent low-temperature toughness at the same time, and good welding manufacturability and metallurgical purity are taken into account.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of welding materials, in particular to a high-speed rail bogie welding steel and a manufacturing method thereof. BACKGROUND

[0002] As a core component of modern transportation system, the safety and reliability of high-speed trains are of great importance. As the core load-bearing and running part of high-speed trains, the bogie directly bears the weight of the car body, transmits traction / braking force, and guides the train to run safely and smoothly along the track. Due to its critical function, the structural integrity of the bogie, especially the performance of its welded joints, is directly related to the safety of train operation and the safety of passengers' life and property.

[0003] In the manufacturing and maintenance process of high-speed train bogies, welding is an essential key process. The performance of welding materials is a basic factor that determines the final quality of the welded joints. In order to meet the stringent safety requirements of high-speed trains for bogie welding structures, the welding materials not only need to have high purity (very low content of harmful elements and inclusions) and high process stability (to ensure stable welding process, less spatter, and beautiful forming), but also must achieve equal or even superior matching of the weld metal (deposited metal) with the base material of the bogie, and have excellent weather resistance (ability to resist atmospheric corrosion, stress corrosion, etc.), in order to cope with complex alternating loads and harsh environmental conditions in high-speed operation.

[0004] Currently, vehicle manufacturers have clear technical index requirements for welding wires used for high-speed rail bogie welding: the deposited metal of the welding wire must meet the requirements of tensile strength ≥500MPa and impact toughness ≥60J at extremely low temperature environment (-40℃). These indicators aim to ensure that the welded joints can maintain sufficient strength and resistance to brittle fracture under high-speed operation, low temperature environment and complex stress state. However, at the same time, achieving such high strength and excellent low temperature toughness, especially ensuring the stability and consistency of the deposited metal in mass production, poses a great challenge to the composition design and metallurgical process of the wire rod for welding wire (welding wire raw material). Existing conventional welding materials often cannot meet both indicators at the same time, or sacrifice welding process performance (such as molten pool fluidity, slag removal, etc.) or purity requirements while meeting the indicators. For example, in order to improve the fluidity of the molten pool metal during welding and improve the weld forming (ensure smooth weld), a certain amount of sulfur needs to be designed and added to the steel, but this may have a negative impact on toughness and purity control. How to accurately balance these mutually restrictive factors is a technical difficulty.

[0005] Therefore, how to develop a high-speed rail bogie welding steel and a manufacturing method thereof, so that the deposited metal of the welding wire made of the high-speed rail bogie welding steel can stably and reliably meet the core performance indicators of high strength (tensile strength ≥ 500 MPa) and excellent low temperature toughness (impact toughness ≥ 60 J at-40 ℃ temperature), and also consider good welding process and metallurgical purity, is an important technical problem to be solved in the field. SUMMARY

[0006] To solve the above-mentioned technical problems in the prior art, the present application provides a high-speed rail bogie welding steel and a manufacturing method thereof.

[0007] The technical scheme of the present application is as follows:

[0008] In a first aspect, a high-speed rail bogie welding steel is provided, comprising the following components in percentage by weight:

[0009] C: 0.04-0.08%, Si: 0.45-0.60%, Mn: 1.40-1.60%, P: ≤0.015%, S: 0.010-0.018%, Cr: 0.40-0.60%, Ni: 0.35-0.50%, Cu: 0.22-0.35%, Ti: 0.025-0.050%, Al: ≤0.015%, As+Sn+Pb ≤0.012%, the balance being Fe and inevitable impurity elements.

[0010] In some optional embodiments, the high-speed rail bogie welding steel comprises the following components in percentage by weight:

[0011] C: 0.065%, Si: 0.50%, Mn: 1.50%, P: ≤0.010%, S: 0.012%, Cr: 0.45%, Ni: 0.38%, Cu: 0.27%, Ti: 0.035%, Al: ≤0.012%, As+Sn+Pb ≤0.010%, the balance being Fe and inevitable impurity elements.

[0012] In a second aspect, a manufacturing method of the above-mentioned high-speed rail bogie welding steel is also provided, the method comprising at least the following steps:

[0013] Rough smelting: adding molten iron and scrap steel into a converter to smelt into rough molten steel, and then tapping, wherein P ≤0.010% when tapping, the tapping temperature is >1650℃, and aluminum pellets 3.5-4.0 kg / ton of steel, lime 7-7.5 kg / ton of steel, synthetic slag 2.5-3.0 kg / ton of steel, silicon-manganese alloy, manganese iron and chromium iron are added with the steel flow when tapping;

[0014] LF refining: the crude steel water is added into the LF ladle refining furnace for refining, the molten slag is adjusted to be alkaline slag in the LF ladle refining furnace, and manganese iron, chromium iron, nickel iron, copper plate, sulfur iron, titanium iron are added to finely adjust the composition of the steel water, and the chemical composition of the refined steel water is controlled to be: C 0.05-0.07%, Si 0.47-0.58%, Mn 1.45-1.60%, P≤0.015%, S 0.011-0.015%, Cr 0.42-0.55%, Ni 0.36-0.45%, Al≤0.012%, Cu 0.23-0.30%, Ti 0.030-0.045%, and the balance is Fe and inevitable impurity elements;

[0015] RH refining: after the LF refining is completed, the ladle is transported to the RH vacuum station for vacuum treatment, during the vacuum treatment, the vacuum degree is controlled to be≤4mbar and maintained for more than 10 minutes, after breaking the vacuum, the on-line [H] is controlled to be≤2.0ppm, and argon gas soft stirring is performed for 10-15 minutes, and the RH outlet station temperature is controlled to be 1545-1555℃;

[0016] Continuous casting: after the RH refining is completed, the continuous casting is performed, the continuous casting billet is a square billet, during the continuous casting, argon protection is adopted, the tundish pouring temperature is 1540-1550℃, the ladle pouring temperature is 1530-1545℃, the casting billet casting speed is 0.85±0.05m / min, the crystallizer liquid level fluctuation is≤±3mm, the crystallizer adopts electromagnetic stirring, the electromagnetic stirring current is 200±5A, the frequency is 3.5±0.1Hz, the terminal electromagnetic stirring current is 450±5A, the frequency is 4.5±0.1Hz, the commutation period is 14-16 seconds, and the continuous casting is followed by air cooling;

[0017] Wire rod rolling: after the continuous casting billet is heated at a heating temperature of 1100-1150℃ for more than 2 hours, rough rolling and finish rolling are sequentially performed, and the continuous casting billet is rolled into a wire rod with a thickness specification of 5.5-6.5mm;

[0018] On-line stress relief treatment: the rolled wire rod is transported to the roller hearth furnace for on-line annealing treatment, the wire rod inlet temperature is≥450℃, the wire rod is heated to 600-650℃ in the roller hearth furnace and is maintained for 1.0-1.5 hours, and the wire rod is discharged below 600℃ after the maintaining treatment and is air cooled.

[0019] In some optional embodiments, in the step of rough refining, the addition amounts of the silicon-manganese alloy, the manganese iron and the chromium iron are controlled, so that the C, Si, Mn, P, S and Cr in the crude steel water are controlled to be: C 0.04-0.08%, Si 0.30-0.40%, Mn 1.45-1.60, P≤0.015%, S≤0.030%, and Cr 0.40-0.50% by weight percentage.

[0020] In some alternative embodiments, in the step of LF refining, the refining slag basicity is adjusted to 1.82±0.02, the ladle is stirred by bottom blowing argon, and the bottom blowing argon flow is 1100±50 L / min.

[0021] In some alternative embodiments, in the step of LF refining, the chemical composition of the refining molten steel is controlled as follows in terms of percentage by weight: C 0.065%, Si 0.50%, Mn 1.50%, P≤0.010%, S 0.012%, Cr 0.45%, Ni 0.38%, Al≤0.012%, Cu 0.27%, Ti 0.035%, and the balance being Fe and inevitable impurity elements.

[0022] In some alternative embodiments, in the step of continuous casting, the mold submerged entry nozzle insertion depth is 120±5 mm, the mold cooling water amount is 1800±20 L / min, and the secondary cooling specific water amount is 0.2±0.05 L / Kg.

[0023] In some alternative embodiments, in the step of continuous casting, the billet specification is 220±5×220±5 mm.

[0024] In some alternative embodiments, in the step of wire rod rolling, the rough rolling opening rolling temperature is≥1050℃, the finish rolling inlet temperature is≥950℃, the finish rolling outlet temperature is 800-850℃, the wire drawing temperature is 750-850℃, and the rolling controlled cooling mode is: fan full off, and heat preservation cover full closed, and the air cooling roller speed is 0.10-0.25 m / s.

[0025] In some alternative embodiments, the tensile strength of the manufactured wire rod is 500-600 MPa.

[0026] The main advantages of the technical scheme of the present application are as follows:

[0027] The high-speed rail bogie welding steel and the manufacturing method thereof can make the deposited metal of the welding wire made of the high-speed rail bogie welding steel to stably and reliably meet the core performance indexes of high strength (tensile strength≥500 MPa) and excellent low-temperature toughness (impact toughness≥60 J at-40℃), and also consider good welding process and metallurgical purity. BRIEF DESCRIPTION OF DRAWINGS

[0028] The drawings described herein are used to provide further understanding of the embodiments of the present application, and form a part of the present application. The schematic embodiments of the present application and the descriptions thereof are used to explain the present application, and do not constitute improper limitation on the present application. In the drawings:

[0029] Figure 1A schematic diagram of a metallographic structure of a wire rod prepared by the manufacturing method of the high-speed rail bogie welding steel provided by the embodiment of the present application;

[0030] Figure 2 A schematic diagram of a metallographic structure of a deposited metal of a welding wire made of the wire rod prepared by the embodiment of the present application. DETAILED DESCRIPTION

[0031] In order to make the objectives, technical solutions and advantages of the present application clearer, the technical solutions of the present application will be described below in detail with reference to the specific embodiments of the present application and corresponding drawings. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0032] The technical solutions provided by the embodiments of the present application will be described in detail below with reference to the drawings.

[0033] In a first aspect, the embodiments of the present application provide a high-speed rail bogie welding steel, which comprises the following components in terms of weight percentage:

[0034] C: 0.04-0.08%, Si: 0.45-0.60%, Mn: 1.40-1.60%, P: ≤0.015%, S: 0.010-0.018%, Cr: 0.40-0.60%, Ni: 0.35-0.50%, Cu: 0.22-0.35%, Ti: 0.025-0.050%, Al: ≤0.015%, As+Sn+Pb ≤0.012%, and the balance being Fe and inevitable impurity elements.

[0035] In the high-speed rail bogie welding steel provided by the embodiments of the present application, the content of the above elements is controlled to be in the above range, which is a key factor to realize that the deposited metal of the welding wire made of the high-speed rail bogie welding steel can stably and reliably meet the core performance indexes of high strength (tensile strength of 500-600 MPa) and excellent low-temperature toughness (impact toughness ≥60 J at -40 ℃ temperature), and also take into account good welding process and metallurgical purity. The action mechanism of each element is as follows:

[0036] Carbon is a basic strengthening element, which improves the strength of the deposited metal by solid solution strengthening, and when the carbon content is too low, it will lead to insufficient strength, which is difficult to meet the tensile strength requirement of ≥500MPa; when the carbon content is too high, it will damage the weldability, specifically, it will increase the hardening tendency of the weld heat-affected zone (HAZ), leading to cold crack risk, reducing low temperature toughness, and when the carbon content is greater than 0.10%, it may cause strength mismatch between the deposited metal and the bogie base material, leading to stress concentration. Therefore, in the embodiments of the present application, the carbon content is controlled to be 0.04-0.08%, preferably 0.065%.

[0037] Silicon is a strong deoxidizing agent, which can reduce the oxygen content in steel, improve the purity of the deposited metal, improve the strength by solid solution strengthening, and improve the fluidity of the molten pool; however, excessive silicon will deteriorate toughness, specifically, it will promote the formation of high-hardness silicate inclusions, become a crack source, inhibit the transformation of acicular ferrite, coarsen the microstructure, leading to an increase in welding spatter, affecting process stability. Therefore, in the embodiments of the present application, the silicon content is controlled to be 0.45-0.60%, preferably 0.50%.

[0038] Manganese is a core strengthening and toughening element, which improves strength by solid solution strengthening, refines grains and promotes the formation of acicular ferrite, significantly improves low temperature toughness (-40℃ impact energy ≥60J), and can reduce FeS thermal brittleness by forming MnS with sulfur; however, excessive manganese will damage weldability, specifically, it will increase hardenability, leading to HAZ hardening, promoting the formation of high-carbon martensite, reducing impact toughness, and manganese is a major alloying element, with high cost. Therefore, in the embodiments of the present application, the manganese content is controlled to be 1.40-1.60%, preferably 1.50%.

[0039] Sulfur can improve welding processability, form MnS to improve molten pool fluidity, make the weld smooth and beautiful, and reduce welding spatter; however, excessive sulfur will seriously damage toughness, form long strip-shaped MnS inclusions, become a crack propagation path, cause sulfur segregation, lead to anisotropy of the deposited metal, and reduce low temperature impact energy. Therefore, in the embodiments of the present application, the sulfur content is controlled to be 0.010-0.018%, preferably 0.012%.

[0040] Chromium can improve corrosion resistance (and Cu cooperates to enhance weather resistance), adapt to outdoor service environment of bogie, and improve strength by solid solution strengthening and carbide formation; however, excessive chromium will deteriorate low temperature toughness, specifically, it will promote the precipitation of carbides, become a brittle fracture source, increase hardenability, and increase cold crack sensitivity. Therefore, in the embodiments of the present application, the chromium content is controlled to be 0.40-0.60%, preferably 0.45%.

[0041] Nickel is a low-temperature toughness core element, which can stabilize austenite, refine grains, inhibit brittle phase precipitation, and significantly improve the impact energy at-40 DEG C; however, excessive nickel can reduce the Ac1 point, affect the post-weld heat treatment process, and nickel is an expensive alloy element with high cost. Therefore, in the embodiment of the application, the nickel content is controlled to be 0.35-0.50%, preferably 0.38%.

[0042] Copper is a key element for weather resistance, which can form a dense oxide film (such as CuO) on the surface to resist atmospheric corrosion and assist solid solution strengthening; however, excessive copper can cause hot brittleness, easily segregate at the grain boundary in the welding thermal cycle, induce microcracks, and possibly cause 'copper contamination' on the weld surface. Therefore, in the embodiment of the application, the copper content is controlled to be 0.22-0.35%, preferably 0.27%.

[0043] Titanium is a structure refining agent, which can form TiN particles to pin the grain boundary, inhibit HAZ grain growth, promote the generation of acicular ferrite, and improve strength and toughness; however, excessive titanium can damage the welding quality, form coarse TiC / TiN inclusions, become a crack source, cause the weld surface to oxidize and turn black, and reduce the purity of the deposited metal. Therefore, in the embodiment of the application, the titanium content is controlled to be 0.025-0.050%, preferably 0.035%.

[0044] Phosphorus, aluminum, arsenic, tin, and lead are harmful elements, and in the embodiment of the application, the phosphorus content is controlled to be ≤0.015%, preferably ≤0.010%, the aluminum content is controlled to be ≤0.015%, preferably ≤0.012%, and the content of arsenic + tin + lead is controlled to be ≤0.012%, preferably ≤0.010%, which can avoid the adverse effects of the above elements.

[0045] In a second aspect, the embodiment of the application also provides a manufacturing method of the high-iron bogie welding steel as described above, which at least includes the following steps:

[0046] Coarse smelting: the molten iron and scrap steel are added to the converter to smelt into coarse molten steel, and the P≤0.010% when tapping, the tapping temperature is >1650 DEG C, and the aluminum shot 3.5-4.0 kg / ton of steel, lime 7-7.5 kg / ton of steel, synthetic slag 2.5-3.0 kg / ton of steel, silicon-manganese alloy, manganese iron and chromium iron are added with the steel flow when tapping;

[0047] LF refining: the crude molten steel is added into the LF ladle refining furnace for refining, the slag in the LF ladle refining furnace is adjusted to be alkaline slag, and manganese iron, chromium iron, nickel iron, copper plate, sulfur iron, titanium iron are added to finely adjust the composition of the molten steel, and the chemical composition of the refined molten steel is controlled to be: C 0.05-0.07%, Si 0.47-0.58%, Mn 1.45-1.60%, P≤0.015%, S 0.011-0.015%, Cr 0.42-0.55%, Ni 0.36-0.45%, Al≤0.012%, Cu 0.23-0.30%, Ti 0.030-0.045%, and the balance is Fe and inevitable impurity elements;

[0048] RH refining: after the LF refining is completed, the ladle is transported to the RH vacuum station for vacuum treatment, during the vacuum treatment, the vacuum degree is controlled to be≤4mbar and maintained for more than 10 minutes, after breaking the vacuum, the on-line [H] is controlled to be≤2.0ppm, and argon gas soft stirring is performed for 10-15 minutes, and the RH outlet station temperature is controlled to be 1545-1555℃;

[0049] Continuous casting: after the RH refining is completed, continuous casting is performed, the continuous casting billet is a square billet, during the continuous casting process, argon protection is adopted, the tundish pouring temperature is 1540-1550℃, the ladle pouring temperature is 1530-1545℃, the casting billet casting speed is 0.85±0.05m / min, the crystallizer liquid level fluctuation is≤±3mm, the crystallizer adopts electromagnetic stirring, the electromagnetic stirring current is 200±5A, the frequency is 3.5±0.1Hz, the terminal electromagnetic stirring current is 450±5A, the frequency is 4.5±0.1Hz, the commutation period is 14-16 seconds, and the continuous casting is air cooled after the continuous casting;

[0050] Wire rod rolling: after the continuous casting billet is heated at a heating temperature of 1100-1150℃ for more than 2 hours, rough rolling and finish rolling are sequentially performed, and the continuous casting billet is rolled into a wire rod with a thickness specification of 5.5-6.5mm;

[0051] On-line stress relief treatment: the rolled wire rod is transported to the roller hearth furnace for on-line annealing treatment, the wire rod enters the furnace at a temperature of≥450℃, is heated to 600-650℃ in the roller hearth furnace and is maintained for 1.0-1.5 hours, and is air cooled after the maintaining treatment at a temperature of≤600℃.

[0052] In the embodiment of the present application, by controlling the phosphorus content to be ≤0.010% and the temperature to be >1650℃ when the crude steel is refined, the oxidation can be reduced, the risk of cold brittleness is reduced, and the purity is laid for subsequent refining; by adding aluminum pellets, lime, synthetic slag, silicon manganese alloy, manganese iron and chromium iron into the steel stream when the steel is tapped, the slag can be quickly deoxidized and formed, the oxidation of the molten steel is reduced, the inclusions are adsorbed by the synthetic slag, and the cleanliness of the molten steel is improved; by adjusting the composition in the LF refining, the strength and low-temperature toughness can be improved, the sulfide morphology can be improved, the anisotropy can be reduced, the TiC / N precipitated phase can be formed, the grain can be refined and the strength can be improved; by using the above-mentioned RH refining treatment, the composition homogenization can be promoted and the segregation can be reduced; by using the above-mentioned continuous casting treatment, the center segregation can be reduced, the solidification structure can be refined, the internal cracks can be reduced, the homogeneity of the casting blank can be improved, and the secondary oxidation of the molten steel can be prevented; by using the above-mentioned rolling treatment, fine and uniform ferrite-pearlite structure can be obtained; by using the above-mentioned on-line stress relief treatment, the rolling internal stress can be eliminated, the wire rod hardness can be reduced, the tensile strength of the wire rod can be controlled to be 500-600MPa, the cold drawing workability can be improved, and the drawing into welding wire is facilitated.

[0053] Further, in the embodiment of the present application, in the step of crude refining, the addition amounts of silicon manganese alloy, manganese iron and chromium iron are controlled, so that the C, Si, Mn, P, S and Cr in the crude molten steel are controlled to be: C 0.04-0.08%, Si 0.30-0.40%, Mn 1.45-1.60, P≤0.015%, S≤0.030%, and Cr 0.40-0.50% by weight percentage.

[0054] In the embodiment of the present application, by controlling the composition of the crude molten steel, excessive carbon / silicon increase in the crude refining stage can be avoided, the refining adjustment difficulty is reduced, and the subsequent fine-tuning efficiency is ensured by pre-controlling the chromium content.

[0055] Further, in the embodiment of the present application, in the step of LF refining, the refining slag basicity is adjusted to be 1.82±0.02, the ladle is stirred and reduced by bottom blowing argon, and the bottom blowing argon flow is 1100±50L / min.

[0056] In the embodiment of the present application, by controlling the basicity to be 1.82±0.02, deep desulfurization and inclusion adsorption can be achieved, and by bottom blowing argon at a flow rate of 1100±50L / min, the slag-steel reaction can be strengthened and the composition / temperature homogenization can be promoted.

[0057] Further, in the embodiment of the present application, in the step of LF refining, the chemical composition of the refined molten steel is controlled as follows in terms of percentage by weight: C 0.065%, Si 0.50%, Mn 1.50%, P≤0.010%, S 0.012%, Cr 0.45%, Ni 0.38%, Al≤0.012%, Cu 0.27%, Ti 0.035%, and the balance of Fe and inevitable impurities.

[0058] In the embodiment of the present application, by precisely controlling the composition in the step of LF refining, the mechanical property stability of the final product can be ensured, and the performance of the final product can meet the requirements.

[0059] Further, in the embodiment of the present application, in the step of continuous casting, the immersion nozzle insertion depth of the crystallizer is 120±5mm, the crystallizer cooling water amount is 1800±20L / min, and the secondary cooling specific water amount is 0.2±0.05L / Kg.

[0060] In the embodiment of the present application, by controlling the immersion nozzle insertion depth of the crystallizer and the crystallizer cooling water amount, the crystallizer flow field can be stabilized, and the risk of slag entrapment can be reduced, and by controlling the secondary cooling specific water amount, the hot stress crack of the casting blank can be reduced.

[0061] Further, in the embodiment of the present application, in the step of continuous casting, the specification of the bloom is 220±5×220±5mm.

[0062] In the embodiment of the present application, the specification of the bloom is set to 220±5×220±5mm, which can match the subsequent rolling compression ratio, and the compactness of the wire rod structure can be ensured.

[0063] Further, in the embodiment of the present application, in the step of wire rod rolling, the rough rolling opening rolling temperature is≥1050℃, the finish rolling inlet temperature is≥950℃, the finish rolling outlet temperature is 800-850℃, the wire drawing temperature is 750-850℃, and the rolling and cooling mode is: fan full off, heat preservation cover full closed, and the air cooling roller speed is 0.10-0.25m / s.

[0064] In the embodiment of the present application, by the above temperature control rolling, the austenite grain growth can be inhibited, and the ferrite-pearlite structure can be refined, and by the above cooling treatment, the martensite phase change can be avoided, and the high plasticity can be ensured.

[0065] Further, in the embodiment of the present application, the tensile strength of the wire rod manufactured is 500-600MPa.

[0066] In order to make the above technical solutions of the present application clearer, the technical solutions of the present application will be described clearly and completely below in combination with the specific embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, but not all the embodiments.

[0067] Example 1

[0068] The φ5.5mm rod was prepared in Example 1, and the welding wire was made based on the prepared rod, and the deposition test was carried out, and the specific steps were as follows:

[0069] Rough refining: 72.3 tons of molten iron and 13.5 tons of scrap steel were added to the converter, oxygen was blown, phosphorus was oxidized, and the molten steel was smelted into rough molten steel, and the tapping temperature was >1650℃, and the chemical composition of the molten steel (by weight percent) was: C 0.05%, Si 0.03%, Mn 0.08%, P 0.008%, S≤0.010%, and the rest was Fe and unavoidable impurities; 300kg of aluminum pellets, 600kg of silicon-manganese alloy, 510kg of low-manganese alloy, 600kg of chromium iron, 550kg of lime, and 210kg of synthetic slag were added to the steel stream during tapping.

[0070] LF refining: the rough molten steel was added to the LF ladle refining furnace for refining, the slag in the LF ladle refining furnace was adjusted to be basic slag, the refining slag basicity was 1.82, and the argon gas was stirred at a flow rate of 1100L / min; then, the molten steel composition was fine-tuned by adding manganese iron, chromium iron, nickel iron, copper plate, sulfur iron, and titanium iron, and the chemical composition of the refined molten steel (by weight percent) was: C 0.06%, Si 0.48%, Mn 1.53%, P 0.01%, S 0.012%, Cr 0.47%, Ni 0.38%, Al 0.010%, Cu 0.26%, Ti 0.030%, and the balance was Fe and unavoidable impurities;

[0071] RH refining: after the LF refining was completed, the ladle was transferred to the RH vacuum station, vacuum was extracted, the vacuum degree reached 4mbar, and was maintained for 15 minutes, the air was broken, the online [H] was 0.8ppm, the argon gas was stirred for 12 minutes, and after the covering agent was added, the station was discharged at 1552℃;

[0072] Continuous casting: after the RH refining was completed, continuous casting was carried out, the continuous casting billet was a square billet with a cross-sectional size of 220x220mm, the tundish baking temperature was greater than 1150℃, argon protection was used throughout the continuous casting process, the ladle casting temperature was 1550℃, the tundish casting temperature was 1545℃, the crystallizer immersion type nozzle insertion depth was 120mm, the stable casting speed of the billet was 0.85m / min, the crystallizer cooling water amount was 1800L / min, the secondary cooling water amount was 0.2L / Kg, the crystallizer used electromagnetic stirring, the current was 200A, the frequency was 3.5Hz, the end electromagnetic stirring current was 450A, the frequency was 4.5Hz, the commutation was 15 seconds, and the continuous casting billet was naturally cooled in air (avoiding air cooling or water cooling);

[0073] Rod rolling: after heating the continuous casting billet at 1120 DEG C for 2.5 hours, rough rolling and finish rolling are carried out in sequence, the rough rolling opening rolling temperature is 1070 DEG C, the finish rolling inlet temperature is 960 DEG C, the finish rolling outlet temperature is 840 DEG C, the wire feeding temperature is 830 DEG C, the rolling and cooling mode is: fan full off, heat preservation cover full close, the air cooling roller speed is 0.15 m / s, the continuous casting billet is rolled into a rod with a thickness of 5.5 mm;

[0074] Online stress relief treatment: the rolled rod is transported to the roller hearth furnace for online annealing treatment, the rod inlet temperature is 510 DEG C, the coal gas is heated to 650 DEG C in the roller hearth furnace for 1.0 hours, and the rod is discharged at 540 DEG C for air cooling after the heat preservation treatment.

[0075] Reference Figures 1-2 , Figure 1 The microstructure schematic diagram of the rod prepared by the manufacturing method of the high-speed rail bogie welding steel provided by the embodiment of the present application; Figure 2 The microstructure schematic diagram of the deposited metal of the welding wire made of the rod prepared by the embodiment of the present application. In the embodiment of the present application, the mechanical properties of the manufactured rod are detected, and the properties are shown in the following table:

[0076]

[0077] Further, in the embodiment of the present application, the rod is coarsely drawn to φ5.5 mm, then finely drawn to φ2.35 mm, and finally finely drawn to φ1.2 mm under normal temperature, and then copper plating is performed to complete the manufacturing of the welding wire, the welding wire with φ1.2 mm is used to carry out the deposition test according to GB / T8110, and the properties of the deposited metal are shown in the following table:

[0078]

[0079] It can be seen that the high-speed rail bogie welding steel and the manufacturing method thereof provided by the embodiment of the present application can make the deposited metal of the welding wire made of the high-speed rail bogie welding steel meet the core performance indexes of high strength (tensile strength ≥500 MPa) and excellent low temperature toughness (impact toughness ≥60 J at-40 DEG C) stably and reliably, and good welding process and metallurgical purity are also considered.

[0080] It should be noted that, in this article, relational terms such as "first" and "second", and the like, are used solely to distinguish one entity or action from another, without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus. In addition, "front", "rear", "left", "right", "upper", "lower", and the like, are all referred to the placement state shown in the drawings.

[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not limited thereto; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can still be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A high-speed railway bogie welding steel, characterized in that, Comprises the following ingredients by weight percentage: C: 0.04-0.08%, Si: 0.45-0.60%, Mn: 1.40-1.60%, P: ≤0.015%, S: 0.010-0.018%, Cr: 0.40-0.60%, Ni: 0.35-0.50%, Cu: 0.22-0.35%, Ti: 0.025-0.050%, Al: ≤0.015%, As+Sn+Pb ≤0.012%, the balance of Fe and inevitable impurity elements.

2. Steel for high-speed railway bogie welding according to claim 1, characterized in that, Comprises the following ingredients by weight percentage: C: 0.065%, Si: 0.50%, Mn: 1.50%, P: ≤0.010%, S: 0.012%, Cr: 0.45%, Ni: 0.38%, Cu: 0.27%, Ti: 0.035%, Al: ≤0.012%, As+Sn+Pb ≤0.010%, the balance of Fe and inevitable impurity elements.

3. A method of manufacturing a high-iron bogie welding steel according to claims 1-2, characterized in that, At least the following steps: Rough smelting: the molten iron and scrap steel are added into the converter to smelt into the crude molten steel, and the P≤0.010% when tapping, the tapping temperature is >1650℃, and the aluminum shot 3.5-4.0kg / ton of steel, lime 7-7.5kg / ton of steel, synthetic slag 2.5-3.0kg / ton of steel, silicon manganese alloy, manganese iron and chromium iron are added with the steel flow when tapping; LF refining: the crude molten steel is added into the LF ladle refining furnace for refining, the molten slag is adjusted to be alkaline slag in the LF ladle refining furnace, and the manganese iron, chromium iron, nickel iron, copper plate, sulfur iron, titanium iron are added to fine-tune the composition of the molten steel, and the chemical composition of the refined molten steel is controlled to be: C 0.05-0.07%, Si 0.47-0.58%, Mn 1.45-1.60%, P≤0.015%, S 0.011-0.015%, Cr 0.42-0.55%, Ni 0.36-0.45%, Al≤0.012%, Cu 0.23-0.30%, Ti 0.030-0.045%, the balance of Fe and inevitable impurity elements by weight percentage; RH refining: after the LF refining is completed, the ladle is transported to the RH vacuum station for vacuum treatment, when the vacuum treatment is performed, the vacuum degree is controlled to be ≤4mbar and maintained for more than 10 minutes, the on-line [H] after breaking the vacuum is ≤2.0ppm, the argon gas is blown for soft stirring for 10-15 minutes, and the RH station temperature is controlled to be 1545-1555℃; Continuous casting: after the RH refining is completed, the continuous casting is performed, the continuous casting billet is square billet, in the continuous casting process, the argon gas protection is adopted, the tundish casting temperature is 1540-1550℃, the middle ladle casting temperature is 1530-1545℃, the casting billet speed is 0.85±0.05m / min, the crystallizer liquid level fluctuation is ≤±3mm, the crystallizer adopts electromagnetic stirring, the electromagnetic stirring current is 200±5A, the frequency is 3.5±0.1Hz, the terminal electromagnetic stirring current is 450±5A, the frequency is 4.5±0.1Hz, the commutation period is 14-16 seconds, and the continuous casting is air cooled. The continuous casting billet is heated at a heating temperature of 1100-1150℃ for more than 2 hours, and then rough rolling and finish rolling are sequentially performed to roll the continuous casting billet into a wire rod with a thickness specification of 5.5-6.5mm; The wire rod after rolling is transported to a roller hearth furnace for online annealing treatment, the wire rod enters the furnace at a temperature of ≥450℃, is heated to 600-650℃ in the roller hearth furnace for 1.0-1.5 hours, and is discharged at a temperature below 600℃ for air cooling after the heat preservation treatment.

4. The method of producing a high-speed railway bogie welding steel according to claim 3, characterized by, In the rough refining step, the addition amounts of the silicon-manganese alloy, the manganese iron and the chromium iron are controlled so that the C, Si, Mn, P, S and Cr in the rough molten steel are controlled to be: C 0.04-0.08%, Si 0.30-0.40%, Mn 1.45-1.60, P≤0.015%, S≤0.030%, and Cr 0.40-0.50% by weight percentage.

5. The method of manufacturing a high-speed railway bogie welding steel according to claim 3, characterized in that, In the LF refining step, the refining slag basicity is adjusted to be 1.82±0.02, and the ladle is stirred and reduced by bottom blowing argon gas, and the bottom blowing argon gas flow is 1100±50L / min.

6. The method of manufacturing a high-speed railway bogie welding steel according to claim 3, characterized in that, In the LF refining step, the chemical composition of the refined molten steel is controlled to be: C 0.065%, Si 0.50%, Mn 1.50%, P≤0.010%, S 0.012%, Cr 0.45%, Ni 0.38%, Al≤0.012%, Cu 0.27%, Ti 0.035%, and the balance is Fe and inevitable impurity elements by weight percentage.

7. The method of manufacturing a high-speed railway bogie welding steel according to claim 3, characterized in that, In the continuous casting step, the mold immersion nozzle insertion depth is 120±5mm, and the mold cooling water amount is 1800±20L / min, and the secondary cooling water amount is 0.2±0.05L / Kg.

8. The method of manufacturing a high-speed railway bogie welding steel according to claim 3, characterized in that, In the continuous casting step, the billet specification is 220±5×220±5mm.

9. The method of manufacturing a high-speed railway bogie welding steel according to claim 3, characterized in that, In the wire rod rolling step, the rough rolling opening rolling temperature is ≥1050℃, the finish rolling inlet temperature is ≥950℃, the finish rolling outlet temperature is 800-850℃, the wire drawing temperature is 750-850℃, and the rolling controlled cooling mode is: fan full-off, heat preservation cover full-closed, and the air cooling roller speed is 0.10-0.25m / s.

10. The method of manufacturing a high-speed railway bogie welding steel according to claim 3, characterized in that, The tensile strength of the manufactured wire rod is 500-600MPa.

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