CN106702261B

CN106702261B - Rare earth-containing welding transition steel for high-speed rail and preparation method thereof

Info

Publication number: CN106702261B
Application number: CN201611120914.7A
Authority: CN
Inventors: 夏明许; 李建国; 张浩凡
Original assignee: Qinhuangdao Nine Clean Energy Technology Co Ltd; GONGHUI METALLURGICAL EQUIPMENT TECHNOLOGY (SUZHOU) Co Ltd
Current assignee: Qinhuangdao Nine Clean Energy Technology Co Ltd; GONGHUI METALLURGICAL EQUIPMENT TECHNOLOGY (SUZHOU) Co Ltd
Priority date: 2016-12-08
Filing date: 2016-12-08
Publication date: 2020-02-07
Anticipated expiration: 2036-12-08
Also published as: CN106702261A

Abstract

The invention relates to a rare earth-containing welding transition steel for high-speed rail and a preparation method thereof, which comprises the chemical components, content and manufacturing process of the welding transition steel. The chemical composition range is as follows: c: 0.05-0.2%, Si: less than or equal to 0.5 percent, Cr: 15-18%, Mn: 2.0-6.0%, Ni: 6-13%, Mo: 0.7-1.2%, S + P: less than or equal to 0.025 percent, rare earth silicon iron: 0.5-1.5% and the balance Fe. The manufacturing process flow comprises the following steps: selecting a chemical composition range, formulating a batching scheme, performing power frequency or medium frequency vacuum induction melting, performing vacuum semi-continuous casting, annealing, forging, performing heat treatment, machining and inspecting. The invention provides a welding medium which can adapt to various welding means and is suitable for the connection of high manganese steel and high carbon steel so as to adapt to the complex operating environment of high-speed rail and meet the use requirement of higher operating reliability.

Description

Rare earth-containing welding transition steel for high-speed rail and preparation method thereof

Technical Field

The invention relates to the technical field of metallurgical manufacturing, in particular to rare earth-containing welding transition steel for high-speed rails and a preparation method thereof.

Background

In recent years, the rapid development of high-speed railways and the gradual development of the international market of high-speed rails in China enable the use amount of welding materials for high-speed rails in China to be increased sharply. However, the welding performance of materials such as steel rails, high-manganese turnouts and the like is poor, and the mixed welding technology and process are a worldwide problem due to the large use amount and mixed use on high-speed rails. The high manganese steel and the high carbon steel have larger difference in chemical composition, physical property and mechanical property. When high manganese steel is welded, carbides are easily precipitated in a thermal stress area, and the phenomenon of thermal cracking is also caused by enriched sulfur and phosphorus on a grain boundary; in the welding process of high-carbon steel, due to the hardening phenomenon, the welding stress is large, and cold cracks can also be generated. The welding processes required for these two materials are therefore also different. Generally, the high manganese steel is welded by cold welding in water and chilling after welding, while the high carbon steel is generally preheated to more than 400 ℃ during welding and is welded by hot welding. In addition to the welding process, the two materials also have large differences in their coefficients of thermal expansion, and therefore direct welding also causes large stress deformations, reducing the quality of the welded joint.

In order to solve the problems, the mixed welding of high manganese steel and high carbon steel generally adopts a welding medium with a specific composition. Early steels such as austria (CN1058556A, AT-PS350881) used CrNi steels containing Nb or Ti, such as X10CrNiTi189, X10CrNiNb189, X10CNiTi1810 or X5CrNiNb 1810. German patent (DE-PS2962070) proposes the use of Ni-containing alloys, such as conventional CrNi steels or manganese-containing CrNi steels, as joining materials. Considering that the phenomenon of grain growth and carbide precipitation of the duplex stainless steel is not easy to occur in the heating process, and the melting point, the expansion coefficient and the heat conductivity coefficient of the duplex stainless steel are close to those of high manganese steel with higher requirements on welding, Yanshan university (CN1275463A) proposes that CrMnNiMo series austenite-ferrite duplex steel is used as a connecting medium. In order to overcome the manufacturing problem of the welding medium and reduce the production cost, the medium iron Bao bridge (CN101474713A) adopts the national standard grade stainless steel (0Cr18Ni12Mo2Ti) as the welding medium, so that the cost is low and the practicability is strong. On the basis of the Ni content, the Mo content is reduced, Ti is added in the material, and the constraint P is less than or equal to 0.02 by Shandong far-large die material Co Ltd (hereinafter referred to as Shandong far-large); s is less than or equal to 0.01(CN 101748344A). The latter is required to be subjected to intermediate frequency smelting, electroslag remelting, annealing, blanking, forging, hydrogen diffusion treatment, solution treatment, machining and the like in the manufacturing process, and finally becomes a qualified welding medium, and Shandong is largely defined as welding steel. The welding process of the materials adopts a flash welding method for welding, avoids the influence of temperature on the quality of a welding joint in the welding process, has high welding quality, is efficient and quick, but has high cost and poor portability of welding equipment, and is difficult to meet the requirements of field construction.

In order to adapt to the national conditions of China, a Tangshan railway turnout factory and Harbin industry university (CN1442265A) jointly provide a high-carbon steel rail and high-manganese steel fork-removing welding process method. Aiming at different materials of the steel rail and the removing fork, Cr-Ni-Mo welding materials are respectively adopted on the steel rail side, Mn-Cr-Ni welding materials are respectively adopted on the removing fork side, manual resistance welding is respectively used for surfacing on two sides, and then surfacing welding media are welded to meet the connecting requirements of connecting the steel rail and the removing fork.

However, the welding medium still lacks an effective means for suppressing the welding crack phenomenon of the welding base metal, and the preparation means of the welding material is difficult to meet the increasingly high-iron joint quality requirement, or the manufacturing process is too complicated and the cost is too high. The welding material is closely connected with the welding means, and the flexibility is poor.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides a welding medium which can adapt to various welding means and is suitable for the connection of high manganese steel and high carbon steel so as to adapt to the complex operating environment of high-speed rails and meet the use requirement of higher operating reliability.

The rare earth-containing welding transition steel for the high-speed rail mainly comprises the following components in proportion and a manufacturing process, and is characterized in that: according to the characteristics of the steel for high-speed rail, rare earth components are introduced into the welding transition steel, and the chemical component range is as follows: c: 0.05-0.2%, Si: less than or equal to 0.5 percent, Cr: 15-18%, Mn: 2.0-6.0%, Ni: 6-13%, Mo: 0.7-1.2%, S + P: less than or equal to 0.025 percent, rare earth silicon iron: 0.5-1.5% and the balance Fe.

Furthermore, the manufacturing process adopts a vacuum induction melting in-situ casting method, and comprises the following process steps of proportioning according to chemical components, vacuum induction melting, vacuum in-situ casting, annealing, blanking, forging, solution treatment, machining and checking to prepare the finished welded transition steel.

Further, the vacuum induction melting process mainly comprises 1) adopting a vacuum melting and casting method, wherein the vacuum degree is 10 < -2 > to 102Pa, and the inert gas is refilled to 102 < -103 > Pa so as to reduce the volatilization of Mn; 2) the melt is stirred by adopting power frequency or intermediate frequency smelting to improve the temperature and the components of the melt to be uniform.

Further, the in-situ casting method 1) places a casting mold or a semi-continuous casting tundish in the same vacuum cavity; 2) according to the size of the cast ingot, single-ladle or multi-ladle induction melting and in-situ casting can be selected; 3) the semi-continuous casting adopts a scheme of a tundish and a water-cooled crystallizer to form in a vacuum cavity, and the ingot can be led out of the vacuum cavity by a down-drawing method or a horizontal continuous casting method.

A preparation method of rare earth-containing welding transition steel for high-speed rail comprises the following steps:

step one, determining a batching scheme according to chemical components, and batching at low S, P to obtain pure material blocks with moderate size;

step two, adopting a vacuum single-ladle or multi-ladle induction melting casting scheme, wherein the vacuum degree meets 10 < -2 > -102Pa, selecting single-station or multi-station power frequency or medium frequency induction melting according to the size of the cast ingot, and refilling inert gas to 102-103Pa to reduce the volatilization of Mn;

thirdly, when charging, the large blocks lean against the crucible wall, the small blocks are arranged in the middle and at the bottom, the power is firstly switched on with small power (40-60%), after 10 minutes, the large power is used, and after most of the large blocks are melted, a small amount of slagging material is added;

step four, finishing smelting and standing, and arranging a slag blocking dam at a crucible discharge port or a tundish feed port to block slag;

and step five, pouring the refined molten steel into a casting mould or a semi-continuous casting tundish in the same vacuum chamber according to a set casting process, and solidifying and forming. The semi-continuous casting method can lead out the vacuum cavity by a down-drawing method or a horizontal casting method and carry out secondary cooling outside the vacuum cavity;

and step six, after annealing, blanking, forging and solution treatment, the welding shape and quality requirements are met.

Compared with the prior art, the invention has the following beneficial effects:

the invention can recover the terephthalic acid which is difficult to degrade, saves the treatment cost, combines the multi-effect catalytic oxidation and the biomembrane technology to remove the organic matters in the wastewater, realizes the recycling of sodium sulfate and the recycling of pure water, and really realizes comprehensive step recycling.

Drawings

FIG. 1 is a schematic view of a vacuum power-frequency smelting and in-situ tilt casting apparatus in embodiment 1 of the present invention.

FIG. 2 is a schematic view of a double-ladle vacuum melting and semi-continuous casting apparatus in example 2 of the present invention.

Detailed Description

The invention is further explained with reference to the drawings.

EXAMPLE 1 vacuum line frequency melting Single ladle casting (as shown in FIG. 1)

The welding steel comprises the following components in percentage by weight: c: 0.05-0.2%, Si: less than or equal to 0.5 percent, Cr: 15%, Mn: 6.0%, Ni: 6%, Mo: 0.9%, S + P: less than or equal to 0.025 percent, rare earth silicon iron: 1% and the balance Fe.

Smelting raw materials: electrolytic Mn with the purity not less than 99.9%; electrolyzing Cr; a pure Ni plate; pure Mo rod, industrial pure iron and rare-earth ferrosilicon. Wherein the rare earth ferrosilicon comprises the following components:

Si	Fe	Mn	Ti	Ce	La	Pr	Nd	Sm
									40%	20%	5%	3%	15%	8%	3%	5.1%	0.9%

welding base materials: high carbon steel after forging: u71Mn, water toughening high manganese steel: ZGMn 13.

Vacuum smelting: vacuum power frequency smelting is adopted, a mechanical pump and a roots pump are combined for vacuumizing to 10-2Pa, and inert gas is refilled to 103 Pa. The smelting crucible uses an alkaline furnace lining, and is baked before use at the baking temperature of 250-350 ℃ for 6-8 hours. Except electrolytic manganese and rare earth ferrosilicon, other raw materials are put into a furnace. After the line frequency furnace is electrified for 10 minutes at 60%, the temperature is raised at full power. And keeping the temperature for 30 minutes after the temperature reaches the casting temperature, and keeping the stirring state to ensure that the melt temperature and the components are uniform. Before discharging, putting the electrolytic manganese and the rare earth ferrosilicon into a furnace. And keeping the temperature for 10 minutes, and keeping the melt temperature and the components uniform. Sampling and analyzing the components before discharging, and when the components meet the requirements, retaining the sample and then casting.

Casting: the casting equipment and the vacuum smelting are in the same vacuum cavity, and after the vacuum smelting is finished, in-situ tilting casting is carried out. The casting temperature is 1600-1650 ℃. The mold temperature is controlled at 200-400 ℃.

Forging heat treatment: and blanking the cast ingot, preserving heat and forging. The initial forging temperature is 1100-1200 ℃, and the final forging temperature is 900-950 ℃. After the forging is completed, solution heat treatment is performed.

And (3) machining: and (4) processing and forming the raw material subjected to heat treatment according to the appearance of the workpiece to be welded, and cleaning.

And (4) checking: including profile inspection and performance inspection.

The welding process comprises the following steps: preheating a high-carbon steel joint and welding steel at 400 ℃, carrying out conventional resistance welding or flash welding, then welding the high-manganese steel at the other end, and carrying out forced cooling in the welding process.

EXAMPLE 2 vacuum intermediate frequency melting two-ladle semicontinuous casting (as shown in FIG. 2)

The welding steel comprises the following components in percentage by weight: c: 0.05-0.2%, Si: less than or equal to 0.5 percent, Cr: 15-18%, Mn: 2.0-6.0%, Ni: 6-13%, Mo: 0.7-1.2%, S + P: less than or equal to 0.025 percent, rare earth silicon iron: 0.5-1.5% and the balance of Fe.

Si	Fe	Mn	Ti	Ce	La	Pr	Nd	Sm
									40%	20%	5%	3%	15%	8%	3%	5.1%	0.9%

Vacuum smelting: smelting in a vacuum intermediate frequency furnace, vacuumizing to 10-2Pa by adopting a mechanical pump and roots pump combination, and refilling inert gas to 103 Pa. The smelting crucible uses an alkaline furnace lining, and is baked before use at the baking temperature of 250-350 ℃ for 6-8 hours. Except electrolytic manganese and rare earth ferrosilicon, other raw materials are put into a furnace. And after 50 percent of the intermediate frequency furnace is electrified for 10 minutes, the temperature is raised at full power. And keeping the temperature for 30 minutes after the temperature reaches the casting temperature, and keeping the stirring state to ensure that the melt temperature and the components are uniform. Before discharging, putting the electrolytic manganese and the rare earth ferrosilicon into a furnace. And keeping the temperature for 10 minutes, and keeping the melt temperature and the components uniform. Sampling and analyzing the components before discharging, and semi-continuously casting after sample retention when the components meet the requirements.

Semi-continuous casting: the semi-continuous casting equipment and the vacuum smelting are in the same vacuum cavity, and semi-continuous casting is carried out after the vacuum smelting is finished. The casting temperature is 1600-1650 ℃. The water temperature of the semi-continuous casting crystallizer is controlled between 40 and 60 ℃.

And (4) checking: including profile inspection and performance inspection.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the technical principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims

1. The rare earth-containing welding transition steel for the high-speed rail mainly comprises the following components in proportion and a manufacturing process, and is characterized in that: according to the characteristics of the steel for high-speed rail, rare earth components are introduced into the welding transition steel, and the chemical component range of the welding transition steel containing the rare earth is as follows: c: 0.05-0.2%, Si: less than or equal to 0.5 percent, Cr: 15-18%, Mn: 2.0-6.0%, Ni: 6-13%, Mo: 0.7-1.2%, S + P: less than or equal to 0.025 percent, rare earth silicon iron: 1-1.5% and the balance Fe;

the manufacturing process adopts a vacuum induction melting in-situ casting method and comprises the following process steps of proportioning according to chemical components, vacuum induction melting, vacuum in-situ casting, annealing, blanking, forging, solution treatment, machining and checking to prepare a finished welded transition steel product;

the vacuum induction melting process comprises the following steps: 1) vacuum melting and casting method is adopted, and the vacuum degree is 10^-2-10²Pa, refilling inert gas to 10²-10³Pa to reduce volatilization of Mn; 2) the melt is stirred by adopting power frequency or intermediate frequency smelting to promote the temperature and the components of the melt to be uniform; the vacuum in-situ casting method comprises the following steps: 1) a casting mould or a semi-continuous casting tundish is arranged in the same vacuum cavity; 2) according to the size of the cast ingot, single-ladle or multi-ladle induction melting and in-situ casting can be selected; 3) the semi-continuous casting adopts a scheme of a tundish and a water-cooled crystallizer to form in a vacuum cavity, and a cast ingot can be led out of the vacuum cavity by a down-drawing method or a horizontal continuous casting method;

the preparation method of the rare earth-containing welding transition steel for the high-speed rail comprises the following steps: step one, determining a batching scheme according to chemical components, and batching at low S, P to obtain pure material blocks with moderate size;

step two, adopting a vacuum single-ladle or multi-ladle induction melting casting scheme, wherein the vacuum degree meets 10^-2-10²Pa, selecting single station orMulti-station industrial frequency or medium frequency induction smelting, back filling inert gas to 10²-10³Pa to reduce volatilization of Mn;

thirdly, when charging, the large lump material is close to the crucible wall, the small lump material is arranged in the middle and at the bottom, the power is firstly switched on with small power, after 10 minutes, the large power is used, and after most of the small lump material is melted, a small amount of slagging material is added;

pouring the refined molten steel into a casting mold or a semi-continuous casting tundish in the same vacuum chamber according to a set casting process, solidifying and forming, wherein the semi-continuous casting method can lead out a vacuum chamber by a down-drawing method or a horizontal casting method, and carrying out secondary cooling outside the vacuum chamber;