CN110270775B

CN110270775B - Metal powder core type flux-cored wire for neutron irradiation resistant steel

Info

Publication number: CN110270775B
Application number: CN201910329508.9A
Authority: CN
Inventors: 郭纯; 陈丰; 魏宝丽; 苑风霞
Original assignee: Anhui University of Science and Technology
Current assignee: Anhui University of Science and Technology
Priority date: 2019-04-23
Filing date: 2019-04-23
Publication date: 2020-12-29
Anticipated expiration: 2039-04-23
Also published as: CN110270775A

Abstract

A metal powder core type flux-cored wire for neutron irradiation resistant steel, which comprisesThe flux-cored wire comprises a flux-cored wire and a flux core, wherein the flux-cored wire is made of low-carbon steel, the diameter of the flux-cored wire is 1.0-1.4mm, the flux-cored filling rate is 14% -17%, and the flux core is formed by mixing the following materials in percentage by mass: 55-60% of chromium powder, 8-12% of tungsten powder, 2-4% of ferrovanadium, 2-5% of low-carbon ferromanganese, 1-2% of tantalum pentoxide, 0.05-1% of ferroboron, 2-6% of rutile, 0.5-2% of feldspar and the balance of iron powder. The metal powder core type flux-cored wire for the neutron irradiation resistant steel is suitable for adopting 75-85% of Ar and 15-25% of CO₂The mixed gas (M21) protects the welding of the neutron irradiation resistant steel, and has good welding manufacturability and stable mechanical property.

Description

Metal powder core type flux-cored wire for neutron irradiation resistant steel

Technical Field

The invention relates to a metal powder core type flux-cored wire for neutron irradiation resistant steel.

Background

With the rapid development of the world economy, the demand of human beings on energy is increasing. The energy field generally holds that nuclear power is the only basic energy source capable of replacing thermal power on a large scale. Compared with a thermal power generation mode, nuclear power has the advantages of no emission of pollution gas, high energy conversion efficiency and the like, and compared with energy sources such as water, electricity and wind power, the nuclear power has the advantages of no influence of seasons and climate, high-efficiency and stable power generation and the like.

At present, nuclear energies which have been utilized are mainly nuclear fission energy and nuclear fusion energy. Nuclear fission and nuclear fusion are reactions generated by atomic nuclei under specific conditions, wherein the nuclear fusion has the advantages of abundant nuclear fuel resources, safety, cleanness, no pollution and the like compared with the nuclear fission, and becomes the focus of the current nuclear energy research. The construction of nuclear reactors in nuclear energy utilization processes must have special requirements on the materials used, with resistance to neutron irradiation being one of the required performance requirements for the materials.

The anti-neutron irradiation steel has the advantages of good geometric dimension stability, low irradiation swelling rate and thermal expansion coefficient, excellent thermal conductivity and mechanical property and the like, and is internationally and generally considered to be a preferred structural material for a cladding experiment module of an international thermonuclear fusion experiment reactor and a first wall and a cladding module of a commercial fusion demonstration reactor. The nuclear energy safety of Chinese institute of nuclear fertilizer and material science in Chinese academy of sciences has made an important progress in the research aspect of Chinese anti-neutron irradiation steel (CLAM steel), and can be applied to advanced nuclear energy systems such as fusion reactors, fusion and fission mixed reactors, fission lead-based reactors and the like.

The successful application of any material depends not only on its own unique properties, but also on the solution of secondary processing (e.g., joining, machining, etc.) problems, and the range of applications is greatly limited if not eliminated.

Welding is a necessary connection technology in the process of nuclear reactor construction, but nuclear power technology belongs to high-end technology, so at present, the literature and patent reports about the welding research of the anti-neutron irradiation steel at home and abroad are less, and the literature and patent reports about the special welding material for the anti-neutron irradiation steel are more rarely reported. Chinese patent CN 106312268A discloses a welding process of a low-activity martensitic steel and 316L stainless steel dissimilar steel joint, which adopts argon arc welding technology, and uses a filler wire which is a common ER309 stainless steel solid argon arc welding wire. Chinese patent CN 102259241A discloses a filler wire for low-activation martensitic steel fusion welding and a use method thereof, and the invention provides a solid wire applied to CLAM steel argon arc welding. The welding wire is a solid welding wire for argon arc welding (TIG) as well as a special welding wire for Chinese anti-neutron irradiation steel developed by the institute of science and technology for combined fertilizer substance science, the components of the solid welding wire are almost the same as the chemical components of a CLAM steel plate, the solid welding wire is different from the CLAM steel plate in that the processing mode of a steel ingot after smelting is different, the production process flow of the CLAM steel plate is mainly that the steel ingot is rolled into a plate, the production process flow of the special welding wire for CLAM steel is mainly that the steel ingot is drawn into a wire, the raw materials used by the plate and the wire are the same as the processing mode in the early stage.

At present, the anti-neutron irradiation steel is generally welded by argon arc welding (TIG), and the argon arc welding (TIG) has the advantages of flexible operation, good molten pool protection effect and the like. However, argon arc welding has low welding efficiency, and particularly for welding a thick-wall reactor, a long welding construction period and more welders are needed.

The metal powder core type flux-cored wire is one of flux-cored wires, has the advantages of both solid wires and flux-cored wires, and is the main direction for the development of filling wires in the future. Compared with the solid welding wire metal powder core type flux-cored wire for argon arc welding (TIG), the solid welding wire metal powder core type flux-cored wire has higher current density on the cross section, thereby bringing higher welding efficiency, and has the advantages of no need of slag removal in multilayer and multi-pass welding and greatly improving the working efficiency. The metal powder core type flux-cored wire has better wettability, permeability and side wall fusion performance, can reduce the tendency of unfused defects particularly in the aspects of V-shaped welding seams and fillet welding seams, and has smooth and attractive welding seam surfaces and high welding joint quality. In addition, the flux-cored wire and the solid wire are produced by completely different raw materials and production processes, the flux-cored wire is produced by adopting powder and steel strips as raw materials, and the special welding wire with different components and properties from the neutron irradiation resistant steel plate can be designed according to requirements.

Disclosure of Invention

The invention aims to solve the technical problem of providing a metal powder core type flux-cored wire for neutron irradiation resistant steel, which has good welding manufacturability and stable mechanical property.

In order to solve the technical problems, the invention provides a metal powder core type flux-cored wire for neutron irradiation resistant steel, wherein the outer skin of the flux-cored wire is made of low-carbon steel, the diameter of the flux-cored wire is 1.0-1.4mm, the filling rate of a flux core is 14-17%, and the flux core is formed by mixing the following materials in percentage by mass: 55-60% of chromium powder, 8-12% of tungsten powder, 2-4% of ferrovanadium, 2-5% of low-carbon ferromanganese, 1-2% of tantalum pentoxide, 0.05-1% of ferroboron, 2-6% of rutile, 0.5-2% of feldspar and the balance of iron powder.

Rutile is added into the flux-cored powder of the metal powder core type flux-cored wire, the solidification temperature of rutile slag is high, the all-position weldability can be improved, the addition amount is preferably 2-6%, the all-position weldability is poor when the addition amount is too low, and a large amount of welding slag can be generated on the surface of a welding seam when the addition amount is too high.

The chromium powder is added into the flux core powder of the metal powder core type flux-cored wire, so that the toughness-brittleness transition temperature of the neutron irradiation resistant steel welding joint is mainly reduced, and meanwhile, the strength of the welding joint and the stability under high-temperature neutron irradiation can be improved by adding the chromium. The toughness and brittleness transition temperature of the welding joint is too high when the addition amount is too low, the toughness of the welding joint is not favorable when the addition amount is too high, and a large amount of ferrite is generated in the welding joint when the addition amount of chromium is too large, wherein the addition amount is preferably 55-60%.

The feldspar is added into the flux core powder of the metal powder core type flux-cored wire, and the feldspar can adjust the viscosity of molten iron and slag, so that the all-position welding is facilitated. However, too high an amount of addition causes an increase in smoke and spatter. Therefore, the addition amount of the feldspar is controlled to be between 1 and 3 percent.

The tungsten powder is added into the flux-cored powder of the metal powder-cored flux-cored wire, so that the welding joint has enough strength, and the addition of the tungsten can inhibit the generation of intermetallic compound phases in a heat affected zone of the welding joint. The addition amount is preferably 8-12%, the strength of the welding joint is low when the addition amount is too small, the generation of intermetallic compounds cannot be inhibited, the strength of the welding joint is too high when the addition amount is too large, and the toughness is reduced.

The tantalum pentoxide is added into the flux-cored powder of the metal powder-cored flux-cored wire, and the main purpose is to decompose the tantalum pentoxide and react with carbon to generate a large amount of dispersed carbides in the welding process, control the growth of crystal grains, refine the crystal grains and improve the strength and toughness of the material. The addition amount of tantalum pentoxide is preferably 1% -2%, too low addition amount generates less carbide, the effect of grain refinement is not achieved, too high addition amount can cause decomposition in the welding process to generate a large amount of smoke, and the oxygen content in the weld metal can be increased.

The low-carbon ferromanganese is added into the flux-cored powder of the metal powder-cored flux-cored wire, the main purpose is to improve the tensile strength and toughness of weld metal while deoxidizing the manganese and carbon in the low-carbon ferromanganese, in addition, the formed carbide can play a role in refining crystal grains, the strength of the weld metal with too low content is too low, and the strength and toughness of the weld metal with too high content are reduced. Therefore, the adding amount of the low-carbon ferromanganese is 2 to 5 percent.

According to the metal powder core type flux-cored wire, ferroboron is added into the flux-cored powder, boron is used as a moderator for stopping nuclear reaction in a nuclear reactor, and can absorb neutrons to reduce the reactivity of a welding joint under neutron irradiation and reduce the anti-irradiation expansion performance of the welding joint. The addition amount of the ferroboron is preferably 0.05-1%, boron is a low-melting-point substance, and the excessive addition amount of the ferroboron is easy to precipitate in the weld metal at the grain boundary and easily causes the generation of thermal cracks.

The vanadium iron is added into the powder core powder of the metal powder core type flux-cored wire, vanadium can be deoxidized, weld structure crystal grains can be refined, the strength and toughness of a welding joint are improved, the hydrogen corrosion resistance of the welding joint at high temperature in the nuclear reaction process can be improved by vanadium carbide, and the addition amount is 2-4%.

The invention has the advantages that: the metal powder core type flux-cored wire for the neutron irradiation resistant steel is suitable for adopting 75-85% of Ar and 15-25% of CO₂The mixed gas (M21) protects the welding of the neutron irradiation resistant steel, and has good welding manufacturability and stable mechanical property.

Detailed Description

The first embodiment is as follows:

the utility model provides a metal powder core type flux-cored wire for anti neutron irradiation steel, flux-cored wire crust be low carbon steel, the diameter of flux-cored wire be 1.2mm, the flux-cored filling rate is 15%, the flux core form by the material mixture of following mass ratio: 55% of chromium powder, 10% of tungsten powder, 3% of ferrovanadium, 5% of low-carbon ferromanganese, 1.5% of tantalum pentoxide, 0.08% of ferroboron, 4% of rutile, 1% of feldspar and the balance of iron powder.

Example two:

the utility model provides a metal powder core type flux-cored wire for anti neutron irradiation steel, flux-cored wire crust be low carbon steel, the diameter of flux-cored wire be 1.0mm, the flux-cored filling rate is 17%, the flux core form by the material mixture of following mass ratio: 57% of chromium powder, 8% of tungsten powder, 2% of ferrovanadium, 2% of low-carbon ferromanganese, 1% of tantalum pentoxide, 0.05% of ferroboron, 2% of rutile, 2% of feldspar and the balance of iron powder.

Example three:

the metal powder core type flux-cored wire for the neutron irradiation resistant steel is characterized in that the sheath of the flux-cored wire is made of low-carbon steel, the diameter of the flux-cored wire is 1.4mm, the flux-cored filling rate is 14%, and the flux core is formed by mixing the following materials in percentage by mass: 60% of chromium powder, 12% of tungsten powder, 4% of ferrovanadium, 3% of low-carbon ferromanganese, 2% of tantalum pentoxide, 1% of ferroboron, 6% of rutile, 0.5% of feldspar and the balance of iron powder.

In the above embodiment, the preparation method of the flux-cored wire comprises the following steps: the low-carbon steel strip is used as a sheath, the flux-cored wire is prepared by on-line synchronous addition of the flux-cored powder, and the sheath steel strip added with the flux-cored powder is subjected to roll forming and diameter reduction treatment.

The rutile procurement manufacturer in the above embodiment: tronox Mineral salts Pty Ltd;

feldspar manufacturers in the above embodiments: hebei Lingshouxuexingmica GmbH, product name is baked potash feldspar.

In the above examples, the outer skin was made of a common low carbon steel strip, and the chemical composition and properties are shown in tables 2 and 3. The chemical composition and mechanical properties of the welding wire deposited metal are shown in tables 4 and 5. The welding process parameters used in the examples of the present invention are shown in table 6.

TABLE 1 chemical composition (% by weight) of flux-cored powder for metal powder-cored wire according to example of the present invention

	Chromium powder	Tungsten powder	Vanadium iron	Low-carbon ferromanganese	Tantalum pentoxide	Ferroboron	Rutile type	Feldspar	Iron powder
										Example one	55	10	3	5	1.5	0.08	4	1	Balance of
Example two	57	8	2	2	1.0	0.05	2	2	Balance of
										EXAMPLE III	60	12	4	3	2	1	6	0.5	Balance of

Table 2 chemical components (wt%) of a steel strip used for a metal powder cored flux-cored wire according to an embodiment of the present invention

Chemical composition

C

Si

Mn

S

P

Fe

By weight%

0.035

0.02

0.22

0.005

0.01

Balance of

TABLE 3 Properties of steel strips selected for use in the metal powder cored flux cored wire of the present invention

Performance of	Microhardness (HV)	Tensile strength (MPa)	Elongation (%)
				Guaranteed value	188	340	44

Table 4 chemical composition (% by weight) of deposited metal in metal powder cored type flux cored wire according to example of the present invention

	C	Si	Mn	S	P	Cr	W	Ta	V	B	Fe
												Example one	0.12	0.03	0.60	0.005	0.012	8	1.5	0.17	0.12	0.012	Bal.
Example two	0.10	0.04	0.30	0.005	0.011	9.5	1.6	0.16	0.15	0.008	Bal.
												EXAMPLE III	0.11	0.02	0.35	0.005	0.012	8.5	1.36	0.20	0.22	0.014	Bal.

TABLE 5 mechanical properties (710 ℃ C.. times.2 h heat treatment) of metal deposited by the metal powder cored type flux cored wire according to the embodiment of the present invention

Performance index	Yield strength (MPa)	Tensile strength (MPa)	20 ℃ Charpy impact (J)
				Example 1	510	613	58
Example 2	570	630	50
				Example 3	562	623	54

TABLE 6 welding process parameters of metal powder cored flux-cored wire of the present invention

	Diameter of welding wire/mm	Welding current/A	Welding voltage/V	Dry elongation/mm	Gas flow/(L/min)	Preheating temperature	Temperature between layers	Protective gas
									Example 1	1.2	220	28	15-25	20-25	120	≤150℃	M21
Example 2	1.0	180	24	15-25	20-25	120	≤150℃	M21
									Example 3	1.4	280	32	15-25	20-25	120	≤150℃	M21

Note: current polarity (DCEP).

Claims

1. The utility model provides a metal powder core type flux-cored wire for anti neutron irradiation steel which characterized in that: the flux-cored wire is characterized in that the sheath of the flux-cored wire is made of low-carbon steel, the diameter of the flux-cored wire is 1.0mm, the flux-cored filling rate is 17%, and the flux core is formed by mixing the following materials in percentage by mass: 57% of chromium powder, 8% of tungsten powder, 2% of ferrovanadium, 2% of low-carbon ferromanganese, 1% of tantalum pentoxide, 0.05% of ferroboron, 2% of rutile, 2% of feldspar and the balance of iron powder.