RU2429307C2 - Welding material - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: material contains, wt %: carbon 0.03 - 0.05, silicon 0.2-0.3, manganese 1.0 - 1.5, chromium 11.0 - 14.0, nickel 1.3 - 1.5, molybdenum 0.8 -1.0, vanadium 0.1 - 0.2, niobium 0.04 - 0.08, titanium 0.1 - 0.2, nitrogen 0.010 - 0.015, calcium from over 0.01 to 0.05, iron and impurities - the rest. As impurities material contains, wt %: arsenic 0,005 - 0.010, antimony 0.001 - 0.005, tin 0.001 - 0.005, sulphur 0.006 - 0.010 and phosphorus 0.006 - 0.010. Summary contents of titanium and niobium does not exceed 0.24, while summary contents of arsenic, antimony and tin does not exceed 0.02.

EFFECT: usage of welding material facilitates production of added metal of martensite or martensite-ferrite class possessing high corrosion resistance in steam-water medium and high long-duration strength.

2 cl, 2 tbl

Description

The invention relates to the field of production of welding materials used in nuclear energy, in particular, for welding the bodies of steam generators of a promising installation BN-1200 from 12% chromium steel type 07X12NMFBR.

An analogue in the chemical composition of the proposed welding material is steel grade 07X12NMFBR [1], containing (wt.%):

Carbon 0.05-0.08 Silicon no more than 0.2 Manganese 0.3-0.8 Chromium 11.5-13.0 Nickel 0.8-1.3 Molybdenum 0.8-1.0 Niobium 0.05-0.2 Vanadium 0.05-0.2 Nitrogen no more than 0,035 Aluminum no more than 0,15 Boron calculated 0.001-0.005 Sulfur no more than 0,020 Phosphorus no more than 0,020 Iron rest

However, this material cannot be used as a welding material due to the fact that:

- the chromium content below 12% leads to a loss of corrosion properties of the deposited metal in the operational steam-water environment of the steam generator;

- a high niobium content (0.1-0.2)% contributes to the formation of cracks during welding and embrittlement of the weld metal during heat treatment;

- a low silicon content (not more than 0.2%) with a low manganese content (0.3-0.8%) can lead to the formation of pores during welding due to the low degree of deoxidation of the weld metal;

- the introduction of boron (up to 0.005% by calculation) can lead to cracking during welding, a decrease in the ductility and viscosity of the weld metal.

The closest in composition to the claimed is a corrosion-resistant welding material [2], adopted for the prototype, containing (wt.%):

Carbon + Nitrogen ≤0.3 Silicon ≤1.0 Manganese ≤2.5 Chromium 10.5-21.5 Nickel ≤8.0 Molybdenum ≤3.5 Vanadium ≤0.2 Niobium ≤0.2 Titanium ≤0.3 Calcium ≤0.01 Iron and impurities rest.

The chemical composition of the specified welding wire can vary over a wide range and ensure the production of deposited metal of various structural classes (austenitic, austenitic-ferritic, martensitic, martensitic-ferritic, ferritic, etc.), with various service characteristics of the weld metal and providing high strength and plastic characteristics, corrosion resistance and high long-term strength of the deposited metal at a temperature of 550 ° C may not be provided. To achieve the required properties of the deposited metal in a steam-water medium at a temperature of 550 ° C, it is necessary to give more stringent regulation of the content of chemical elements to ensure that the deposited metal has a martensitic, martensitic-ferritic structure.

The technical result of the invention is the creation of a welding material that provides a deposited metal of martensitic (martensitic-ferritic) class, which has a combination of corrosion resistance in a steam-water medium and high long-term strength while maintaining a high level of resistance to brittle fracture, including during operational aging.

Based on the analysis, a material is proposed as a welding material with high corrosion and long-term strength of the deposited metal at a temperature of 550 ° С, the composition of which strictly regulates the main chemical elements: chromium (11-14)%, carbon (0.03-0.05 )%, manganese (1.0-1.5)%, nickel (1.3-1.5)%, niobium (0.04-0.08)%, vanadium (0.1-0.2)% and calcium (0.01-0.05)%.

The technical result is achieved in that the welding material containing carbon, silicon, manganese, chromium, nickel, molybdenum, titanium, nitrogen and iron additionally contains vanadium, niobium, calcium, arsenic, antimony, tin, sulfur, phosphorus in the following ratio of components ( mass%):

Carbon 0.03-0.05 Silicon 0.2-0.3 Manganese 1.0-1.5 Chromium 11.0-14.0 Nickel 1.3-1.5 Molybdenum 0.8-1.0 Vanadium 0.1-0.2 Niobium 0.04-0.08 Titanium 0.1-0.2 Arsenic 0.005-0.010 Antimony 0.001-0.005 Tin 0.001-0.005 Sulfur 0.006-0.010 Phosphorus 0.006-0.010 Nitrogen 0.010-0.015 Calcium from more than 0.01 to 0.05 Iron rest,

wherein:

- the total content of Ti and Nb should not exceed 0.24;

- the total content of As, Sb, Sn should not exceed 0.02.

The limitation of the chromium content in the range of (11-14)% in combination with Ni (1.3-1.5)% will make it possible to obtain the martensitic (martensitic-ferritic) structure of the deposited metal and provide corrosion resistance of the deposited metal in the steam-water medium, taking into account its burnout in welding process, as well as resistance to thermal embrittlement at a temperature of 550 ° C.

The carbon content (0.03-0.05)%, manganese (1.0-1.5)% with a nickel content (1.3-1.5)% will provide a low content of ferritic component in the martensitic (martensitic-ferritic) structure (not more than 18%) and, accordingly, an increase in the plastic and viscous properties of the weld metal.

The niobium content in the range of (0.04-0.08)% and vanadium (0.1-0.2)% with a titanium content of up to 0.2% with a carbon content of (0.03-0.05)% will provide a high long-term strength of martensitic (martensitic-ferritic) deposited metal at a temperature of 550 ° C.

The total limitation of the content of non-ferrous impurities - arsenic, antimony and tin to 0.02% allows to increase the resistance of the deposited metal against temper brittleness during the manufacturing of the steam generator.

The regulated nitrogen content (0.010-0.015)% helps to increase the resistance to brittle fracture of the surfacing metal by reducing the content of non-metallic inclusions of the nitride type in it.

Keeping calcium (> 0.01-0.05)% in the welding material contributes to the globulation of carbides, providing increased resistance to brittle fracture of the weld metal.

FSUE CRI KM "Prometey" smelted three 100 steel melts for a welding wire of the claimed composition in a 100-kilogram open furnace. Steel was smelted on pure charge materials in terms of sulfur, phosphorus, and color impurities. The casting was carried out in ingots, which were then forged on billets 16 × 16 mm in size with the further manufacture of wire rod with a diameter of 8 mm and drawing it onto a welding wire with a diameter of 3 mm.

Samples for research were made from technological samples with a thickness of 20 mm with a weld made by argon-arc welding with a non-consumable electrode with filler wire of various compositions. In order to exclude the influence of the base metal, welding was performed through preliminary surfacing of edges with a thickness of at least 10 mm, made by the corresponding welding wire. Technological samples were subjected to heat treatment - high tempering at a temperature of 720 ° C.

To study the mechanical properties of the weld metal, the following samples were made:

- for static tension with a diameter of 6 mm and a length of the working part of 30 mm (type II according to GOST 6996);

- on impact bending with a sharp notch 10 × 10 × 55 mm (type IX according to GOST 6996);

- for long-term strength with a diameter of 6 mm and a length of the working part of 30 mm;

- for corrosion resistance - plates 1.5 × 10 × 60 mm.

As a well-known welding material, a corrosion-resistant welding material was chosen [2].

Tensile tests were carried out on a UMD-10 apparatus in air at a strain rate of 3 · 10 ^-3 s ^-1 at a temperature of 550 ° C. Corrosion resistance tests were carried out in an autoclave at a temperature of 550 ° C for 3000 hours. Long-term strength tests were carried out in air in accordance with the requirements of GOST 10145-81 at T = 550 ° C.

The chemical composition of the claimed and known welding material is shown in table 1, mechanical properties in table 2.

The expected technical and economic effect due to the combination of corrosion resistance and high long-term strength of the weld metal of welded joints from 12% chromium steels of type 07X12NMFBR of promising steam generators of the new BN-1200 installation will result in an increase in reliability, safe operation and service life of welded joints.

table 2 The mechanical properties of the weld metal of the claimed and known material Conditional batch number Mechanical properties Deposited metal structure σ _in σ _0.2 δ ψ σ _in σ _0.2 δ ψ Resistance to brittle fracture Corrosion resistance σ for others, MPa MPa % MPa % At 550 ° С, 3 × 10 ⁵ h. + 20 ° C + 550 ° C one 670 615 23 57 450 358 fifteen 58 Provided by Provided by Provides -
Xia (≥122) Martensitic (Martensitic-Ferritic) 2 690 640 23 58 452 360 fourteen 56 3 720 650 25 60 460 365 12 55 four Provided by Provided by Not provided (≤122) Austenitic 5 Not provided Provided by Ferritic Note: 1. The table shows the average values of 3 samples when tested for static tensile

LITERATURE

1. Passport for steel grade 0712NMFB.

2. JP 2003-071589 A, B23K 35/30, 03/11/2003, abstract, formula, description [0028] - [0033].

Claims (2)

1. Corrosion-resistant welding material containing carbon, silicon, manganese, chromium, nickel, molybdenum, titanium, nitrogen and iron, characterized in that it additionally contains vanadium, niobium and calcium in the following ratio, wt.%:
carbon 0.03-0.05 silicon 0.2-0.3 manganese 1.0-1.5 chromium 11.0-14.0 nickel 1.3-1.5 molybdenum 0.8-1.0 vanadium 0.1-0.2 niobium 0.04-0.08 titanium 0.1-0.2 nitrogen 0.010-0.015 calcium from more than 0.01 to 0.05 iron and impurities rest,
the total content of titanium and niobium does not exceed 0.24. 2. Corrosion-resistant welding material according to claim 1, characterized in that it contains arsenic, antimony, tin, sulfur and phosphorus as impurities at the following content, wt.%:
arsenic 0.005-0.010 antimony 0.001-0.005 tin 0.001-0.005 sulfur 0.006-0.010 phosphorus 0.006-0.010,
while the total content of arsenic, antimony and tin does not exceed 0.02.