A control method for grain boundary liquefaction cracks in heat-affected zone of iron-nickel-based alloy welded joints

Abstract

The invention relates to the field of iron-nickel-based alloy welding, in particular to a method for controlling grain boundary liquefaction cracks in the heat-affected zone of an iron-nickel-based precipitation-strengthened austenitic alloy (J75) joint, which solves the problem of easy formation of iron-nickel-based alloy joints in the prior art Problems with wider γ′-poor regions and grain boundary liquefaction cracks. Vacuum electron beam welding is adopted, and its process flow is: pre-welding treatment of the base metal → clamping and fixing in the vacuum welding room → vacuuming the welding room → positioning welding → single-cycle welding with electron beam deflection scanning → post-weld modification welding → post-weld electron beam welding Beam defocus scans the process route of the weld. With the iron-nickel base alloy joint welded by the invention, the heat-affected zone of the joint has no poor gamma' zone and grain boundary liquefaction cracks. The surface of the iron-nickel-based alloy joint welded by the method of the present invention is well formed, the joint strength is above 980MPa, even reaching above 1030MPa, the strength coefficient with the base metal can reach above 0.9, and the joint impact toughness αkU is above 980KJ / m2, even reaching 1020KJ / m2 or more.

Description

technical field

[0001] The invention relates to the field of iron-nickel-based alloy welding, in particular to a method for controlling grain boundary liquefaction cracks in a heat-affected zone of an iron-nickel-based precipitation-strengthened austenitic alloy (J75) joint. Background technique

[0002] With the development of high-tech fields such as aviation, aerospace and nuclear energy utilization, higher requirements are placed on the materials and devices used. Due to the low strength, single-phase austenitic stainless steels such as 304, 310, 316 and 316L no longer meet the requirements of various fields. Precipitation-strengthened austenitic stainless steel is developed on the basis of single-phase austenitic stainless steel through the alloying of elements such as Ti and Al. This type of alloy is used in the aging state and strengthened by precipitation with a coherent relationship with the matrix. Phase γ′-Ni 3 (Al,Ti) to obtain high strength and good plasticity...

Examples

Embodiment 1

[0031] Vacuum electron beam welding of J75 alloy plates with specifications of 180mm (length) × 60mm (width) × 4.0mm (thickness), the specific implementation process is as follows:

[0032] 1. The J75 alloy plate blanks are all hot-rolled plates, and the chemical composition and mechanical properties of the hot-rolled plates meet the requirements of GJB 5724-2006 "Specification for Hydrogen-resistant Steel Bars". The J75 plate was treated at 980°C / 1h, water quenched +740°C / 8h, and air-cooled. The plate after heat treatment is machined to 3.5-4.5 mm (4.0 mm in this embodiment), and the length direction is machined to roughness Ra1.6 μm by grinding machine.

[0033] 2. Carry out decontamination treatment on the base metal after polishing treatment in step 1. During the treatment, petroleum ether is first used to degrease, and then alcohol is used to scrub. The decontamination treatment needs to be carried out within 30 minutes before welding;

[0034] 3. Clamp and fix the J75 a...

Embodiment 2

[0046] The vacuum electron beam welding of the J75 alloy plate with a specification of 120mm (length) × 60mm (width) × 11mm (thickness), differs from Example 1 in that the thickness of the welded J75 alloy plate is 11mm, and the welding process parameters are adjusted accordingly , Post-weld modification welding process parameters and electron beam scanning times.

[0047] The J75 alloy plate blank with the same heat treatment as in Example 1 was adopted, machined to a thickness of 11 mm after heat treatment, and processed to a roughness of Ra1.6 μm by a grinder in the length direction; petroleum ether was used to degrease 30 minutes before welding, and the grinding was scrubbed with alcohol. The base metal after light treatment; then use the butt joint and tight fit method to clamp and fix the two J75 alloy plates in the welding room, and keep the two base metals placed horizontally; close the vacuum welding room and pump the vacuum to 8×10 -3 After Pa, the positioning weldin...

Embodiment 3

[0052] The vacuum electron beam welding of the J75 alloy plate with a specification of 150mm (length) × 80mm (width) × 19mm (thickness), differs from Example 1 in that the thickness of the welded J75 alloy plate is 19mm, and the welding process parameters are adjusted accordingly , Post-weld modification welding process parameters and electron beam scanning times.

[0053] The J75 alloy plate blank with the same heat treatment as in Example 1 was adopted, machined to a thickness of 19 mm after heat treatment, and processed to a roughness of Ra1.6 μm by a grinder in the length direction; petroleum ether was used to degrease 30 minutes before welding, and the grinding was scrubbed with alcohol. The base metal after light treatment; then two pieces of J75 alloy plates are clamped and fixed in the welding room by means of butt joint and tight fit, and the two base metals are placed horizontally; the vacuum welding room is closed and the vacuum degree is evacuated to 5×10 -3 After ...

technical field

[0001] The invention relates to the field of iron-nickel-based alloy welding, in particular to a method for controlling grain boundary liquefaction cracks in a heat-affected zone of an iron-nickel-based precipitation-strengthened austenitic alloy (J75) joint. Background technique

[0002] With the development of high-tech fields such as aviation, aerospace and nuclear energy utilization, higher requirements are placed on the materials and devices used. Due to the low strength, single-phase austenitic stainless steels such as 304, 310, 316 and 316L no longer meet the requirements of various fields. Precipitation-strengthened austenitic stainless steel is developed on the basis of single-phase austenitic stainless steel through the alloying of elements such as Ti and Al. This type of alloy is used in the aging state and strengthened by precipitation with a coherent relationship with the matrix. Phase γ′-Ni 3 (Al,Ti) to obtain high strength and good plasticity...

Examples

Embodiment 1

[0031] Vacuum electron beam welding of J75 alloy plates with specifications of 180mm (length) × 60mm (width) × 4.0mm (thickness), the specific implementation process is as follows:

[0032] 1. The J75 alloy plate blanks are all hot-rolled plates, and the chemical composition and mechanical properties of the hot-rolled plates meet the requirements of GJB 5724-2006 "Specification for Hydrogen-resistant Steel Bars". The J75 plate was treated at 980°C / 1h, water quenched +740°C / 8h, and air-cooled. The plate after heat treatment is machined to 3.5-4.5 mm (4.0 mm in this embodiment), and the length direction is machined to roughness Ra1.6 μm by grinding machine.

[0033] 2. Carry out decontamination treatment on the base metal after polishing treatment in step 1. During the treatment, petroleum ether is first used to degrease, and then alcohol is used to scrub. The decontamination treatment needs to be carried out within 30 minutes before welding;

[0034] 3. Clamp and fix the J75 a...

Embodiment 2

[0046] The vacuum electron beam welding of the J75 alloy plate with a specification of 120mm (length) × 60mm (width) × 11mm (thickness), differs from Example 1 in that the thickness of the welded J75 alloy plate is 11mm, and the welding process parameters are adjusted accordingly , Post-weld modification welding process parameters and electron beam scanning times.

[0047] The J75 alloy plate blank with the same heat treatment as in Example 1 was adopted, machined to a thickness of 11 mm after heat treatment, and processed to a roughness of Ra1.6 μm by a grinder in the length direction; petroleum ether was used to degrease 30 minutes before welding, and the grinding was scrubbed with alcohol. The base metal after light treatment; then use the butt joint and tight fit method to clamp and fix the two J75 alloy plates in the welding room, and keep the two base metals placed horizontally; close the vacuum welding room and pump the vacuum to 8×10 -3 After Pa, the positioning weldin...

Embodiment 3

[0052] The vacuum electron beam welding of the J75 alloy plate with a specification of 150mm (length) × 80mm (width) × 19mm (thickness), differs from Example 1 in that the thickness of the welded J75 alloy plate is 19mm, and the welding process parameters are adjusted accordingly , Post-weld modification welding process parameters and electron beam scanning times.

[0053] The J75 alloy plate blank with the same heat treatment as in Example 1 was adopted, machined to a thickness of 19 mm after heat treatment, and processed to a roughness of Ra1.6 μm by a grinder in the length direction; petroleum ether was used to degrease 30 minutes before welding, and the grinding was scrubbed with alcohol. The base metal after light treatment; then two pieces of J75 alloy plates are clamped and fixed in the welding room by means of butt joint and tight fit, and the two base metals are placed horizontally; the vacuum welding room is closed and the vacuum degree is evacuated to 5×10 -3 After ...

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