Automatic flux-cored wire vertical position welding process for 9Ni steel

Abstract

The invention discloses a flux-cored wire automatic vertical position welding process for 9Ni steel, which comprises the following steps of: S1, according to the technical requirements of the 9Ni steel, smelting the 9Ni steel by an oxygen converter, and performing external refining; the delivery state of the steel plate is quenching and tempering; s2, technical model selection of a matched flux core: selecting a flux-cored wire with the diameter of 1.2 mm; s3, automatic welding equipment is adopted, a welding joint is an X-shaped groove, the depth of a first welding surface accounts for 2 / 3 of the thickness of the steel plate, the angle of the groove is that the first welding surface is 60 degrees, the later welding surface is 60 degrees, the truncated edge is 2 mm, the root gap is 0-3 mm, after welding of the first welding surface of the X-shaped groove is completed, an angle grinder is immediately adopted for cleaning a reverse welding seam, and then welding continues to be conducted; according to the process, flux-cored wire automatic vertical position welding of 9Ni steel is carried out, the welding process is stable and reliable, formed welding seams are attractive and uniform, nondestructive testing and mechanical property testing results of welded joints meet the specification requirements of classification societies, and the stable and reliable welded joints can be obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of welding technology, and in particular relates to a 9Ni steel flux-cored wire automatic vertical welding technology. Background Art

[0002] Commonly used welding methods for 9Ni storage tanks mainly include SMAW and SAW. The welding method using flux-cored wire is not widely used in storage tanks at present. Compared with conventional SMAW and SAW, flux-cored wire has advantages and disadvantages such as high efficiency and low skill level requirements for welders. However, the current performance level of flux-cored wire is lower than that of SMAW and SAW. For this reason, the present invention proposes an automatic vertical welding process for flux-cored wire of 9Ni steel. Summary of the invention

[0003] The object of the present invention is to provide a 9Ni steel flux-cored wire automatic vertical welding process to solve the problems raised in the above background technology.

[0004] To achieve the above object, the present invention provides the following technical scheme: a flux-cored wire automatic vertical welding process for 9Ni steel, S1: technical requirements of 9Ni steel: 9Ni steel is smelted by an oxygen converter and should be refined outside the furnace; the steel plate is delivered in a quenched and tempered state; the chemical composition of 9Ni steel is in accordance with the following requirements (wt%): C≤0.08, Mn0.30-0.80, Si≤0.30, P≤0.008, S≤0.005, Ni8.50-10.00, Mo≤0.10, V≤0.01;

[0005] S2: Technical selection of matching flux core: The diameter of the flux cored wire is 1.2 mm, and the chemical composition of the flux cored wire includes: 0.01 parts of C, 0.3 parts of Mn, 0.4 parts of Si, 0.02 parts of P, 0.001 parts of S, 57.2 parts of Ni, 15.8 parts of Cr, 15.8 parts of Mo, 0.06 parts of Cu, 0.3 parts of Co, 6 parts of Fe, 0.07 parts of V, 3.7 parts of W;

[0006] S3: Automatic welding equipment is used, the welding joint is an X-shaped groove, the depth of the first weld surface accounts for 2 / 3 of the thickness of the steel plate, the groove angle: the first weld surface is 60°, the rear weld surface is 60°, the blunt edge is 2mm, the root gap is 0-3mm, and the X-shaped groove first weld surface is welded immediately after the reverse weld is cleaned with an angle grinder, and then continue welding until the reverse welding is completed. The welding heat input of the base and filler cap welds is controlled to be 1.1-2.4KJ / mm;

[0007] S4: Post-weld inspection: After welding is completed, the surface forming of the weld and the internal quality of the weld are inspected.

[0008] Preferably, the chemical composition of 9Ni steel needs to satisfy Cr+Mo+Cu≤0.50%.

[0009] Preferably, during welding, 100% CO2 shielding gas is used for welding.

[0010] Preferably, before welding, a wire brush or grinder is used to clean the rust and oil stains on the groove surface and both sides of the X-shaped groove until the metallic luster is exposed.

[0011] Preferably, the welding process parameters of the base weld are welding current 150A, welding voltage 26V, welding speed 156mm / min, and the welding current of the filling and capping weld is 160A, welding voltage 26V, and welding speed 114-219mm / min.

[0012] Preferably, the mechanical properties of the 9Ni steel are: tensile strength 680-820N / mm 2 , yield strength ≥585N / mm 2 ; Elongation ≥ 18%, transverse Charpy (V-notch) impact energy meets the test temperature of -196°C, average value 50J, single value 49 / 50 / 51J.

[0013] Preferably, the mechanical properties of the core are: tensile strength 753N / mm 2 , yield strength 484N / mm 2 , elongation 38%, transverse Charpy (V-notch) impact energy meets the test temperature of -196℃, average value ≥80J, single value ≥56J.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: according to the process of the present invention, the flux-cored wire automatic vertical welding of 9Ni steel is carried out, the welding process is stable and reliable, the weld formation is beautiful and uniform, the non-destructive testing and mechanical property testing results of the welded joint meet the specifications of the classification society, and a stable and reliable welded joint can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the process of the present invention;

[0016] Figure 2 It is a structural schematic diagram of the X-shaped groove of the present invention; DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] Example 1

[0019] See also Figure 1 to Figure 2 , which is the first embodiment of the present invention, and provides a technical solution: a flux-cored wire automatic vertical welding process for 9Ni steel, S1: Technical requirements for 9Ni steel: 9Ni steel is smelted by an oxygen converter and should be refined outside the furnace; the steel plate is delivered in a quenched and tempered state; the chemical composition of the smelting analysis of 9Ni steel is in accordance with the following requirements (wt%):

[0020] C Mn Si P S Ni Mo V ≤0.08 0.30-0.80 ≤0.30 ≤0.008 ≤0.005 8.50-10.00 ≤0.10 ≤0.01

[0021] Cr+Mo+Cu≤0.50%, and other grain refining elements may be added in appropriate amounts.

[0022] The mechanical properties of 9Ni steel are as follows:

[0023]

[0024] S2: Technical selection of matching flux core: DW-N609SV flux cored wire is selected, with a diameter of 1.2mm and chemical composition as shown in the following table:

[0025] C Mn Si P S Ni Cr Mo Cu Co Fe V W 0.01 0.3 0.4 0.02 0.001 57.2 15.8 15.8 0.06 0.3 6 0.07 3.7

[0026] The mechanical properties are as follows:

[0027]

[0028] S3: The welding equipment is Kobelco's KI-700 automatic welding equipment, and 100% CO2 shielding gas is used for welding; before welding, the rust and oil stains on the groove surface and both sides of the X-shaped groove are cleaned with a wire brush and grinder until the metallic luster is exposed; the welding joint is an X-shaped groove, the depth of the first welding surface accounts for 2 / 3 of the thickness of the steel plate, the groove angle: the first welding surface is 60°, the rear welding surface is 60°, the blunt edge is 2mm, and the root gap is 0-3mm. After the X-shaped groove first welding surface is completed, the reverse weld is immediately cleaned with an angle grinder, and then welding is continued. Figure 2 As shown, until the reverse side welding is completed, in this embodiment, preferably, the welding process parameters of the base weld are welding current 150A, welding voltage 26V, welding speed 156mm / min, and the welding current of the filling and capping weld is 160A, welding voltage 26V, and welding speed 114-219mm / min; the welding heat input of the base and filling and capping welds is controlled to be 1.1-2.4KJ / mm;

[0029] S4: Post-weld inspection: After welding is completed, the surface forming of the weld and the internal quality of the weld are inspected. The surface forming of the weld meets the technical requirements of ISO 5817. At the same time, the weld is X-rayed and the mechanical properties are tested.

[0030] The weld metal tensile test data is shown in the following table

[0031]

[0032] The impact toughness test results of welded joints are shown in the following table.

[0033]

[0034] Taking the above theories into consideration, the automatic vertical welding of 9Ni steel flux-cored wire is carried out according to the above process. The welding process is stable and reliable, the weld is beautiful and uniform, the non-destructive testing and mechanical properties test results of the welded joints meet the requirements of the classification society, and a stable and reliable welded joint can be obtained.

[0035] Although embodiments of the present invention have been shown and described (see the above detailed description for details), it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A 9Ni steel flux-cored wire automatic vertical welding process, characterized in that: S1: Technical requirements of 9Ni steel: 9Ni steel is smelted by oxygen converter and shall be refined outside the furnace; the steel plate is delivered in the state of quenching and tempering; the chemical composition of 9Ni steel shall be as follows (wt%): C≤0.08, Mn0.30-0.80, Si≤0.30, P≤0.008, S≤0.005, Ni8.50-10.00, Mo≤0.10, V≤0.01; S2: Technical selection of matching flux core: The diameter of the flux cored wire is 1.2 mm, and the chemical composition of the flux cored wire includes: 0.01 parts of C, 0.3 parts of Mn, 0.4 parts of Si, 0.02 parts of P, 0.001 parts of S, 57.2 parts of Ni, 15.8 parts of Cr, 15.8 parts of Mo, 0.06 parts of Cu, 0.3 parts of Co, 6 parts of Fe, 0.07 parts of V, 3.7 parts of W; S3: Automatic welding equipment is used, the welding joint is an X-shaped groove, the depth of the first weld surface accounts for 2 / 3 of the thickness of the steel plate, the groove angle: the first weld surface is 60°, the rear weld surface is 60°, the blunt edge is 2mm, the root gap is 0-3mm, and the X-shaped groove first weld surface is welded immediately after the reverse weld is cleaned with an angle grinder, and then continue welding until the reverse welding is completed. The welding heat input of the base and filler cap welds is controlled to be 1.1-2.4KJ / mm; S4: Post-weld inspection: After welding is completed, the surface forming of the weld and the internal quality of the weld are inspected.

2. The 9Ni steel flux-cored wire automatic vertical welding process according to claim 1 is characterized in that: The chemical composition of 9Ni steel must satisfy Cr+Mo+Cu≤0.50%.

3. The 9Ni steel flux-cored wire automatic vertical welding process according to claim 1 is characterized in that: When welding, 100% CO2 shielding gas is used.

4. The 9Ni steel flux-cored wire automatic vertical welding process according to claim 1 is characterized in that: Before welding, use a wire brush or grinder to clean the rust and oil stains on the groove surface and both sides of the X-shaped groove until the metallic luster is exposed.

5. The 9Ni steel flux-cored wire automatic vertical welding process according to claim 1 is characterized in that: The welding process parameters of the base weld are welding current 150A, welding voltage 26V, welding speed 156mm / min, and the welding current of the filling and capping weld is 160A, welding voltage 26V, and welding speed 114-219mm / min.

6. The 9Ni steel flux-cored wire automatic vertical welding process according to claim 1 is characterized in that: Mechanical properties of the 9Ni steel: tensile strength 680-820N / mm 2 , yield strength ≥585N / mm 2 ; Elongation ≥ 18%, transverse Charpy (V-notch) impact energy meets the test temperature of -196°C, average value 50J, single value 49 / 50 / 51J.

7. The 9Ni steel flux-cored wire automatic vertical welding process according to claim 1 is characterized in that: Mechanical properties of the core: tensile strength 753N / mm 2 , yield strength 484N / mm 2 , elongation 38%, transverse Charpy (V-notch) impact energy meets the test temperature of -196℃, average value ≥80J, single value ≥56J.

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