A welding method for improving ultra-low temperature toughness of 304ln austenitic stainless steel submerged arc welding joints

A technology of austenitic stainless steel and welded joints, which is applied in the direction of welding/welding/cutting articles, welding equipment, welding accessories, etc., which can solve the problems of failing to meet the requirements, unable to improve the ultra-low temperature toughness of 304LN welded joints, and reduce the ultra-low temperature toughness of welded joints, etc.

Active Publication Date: 2021-09-14
WUHAN YIYE STEEL STRUCTURE
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, for some high-end, precision, cutting-edge projects or military products, the low-temperature impact energy of the welded joints at -196°C is required to reach more than 50J or even higher, and the conventional submerged arc welding process cannot meet the requirements.
At the same time, for medium and thick plates, in order to ensure structural stability, post-weld heat treatment is generally used to eliminate residual stress, and heat treatment will greatly reduce the ultra-low temperature toughness of welded joints. If 308L welding wire and supporting flux and conventional welding processes are used, 304LN welded joints cannot be improved. Excellent ultra-low temperature toughness to meet the ultra-low temperature performance of the product
At present, there are almost no domestic research results in this area. In view of this situation, it is necessary to study the welding process to improve the ultra-low temperature toughness of 304LN austenitic stainless steel submerged arc welding joints.

Method used

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  • A welding method for improving ultra-low temperature toughness of 304ln austenitic stainless steel submerged arc welding joints
  • A welding method for improving ultra-low temperature toughness of 304ln austenitic stainless steel submerged arc welding joints
  • A welding method for improving ultra-low temperature toughness of 304ln austenitic stainless steel submerged arc welding joints

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0053] The new submerged arc welding process, the process steps are as follows:

[0054] (1) Preparation before welding

[0055] The 500×150×40mm (2 pieces) 304LN austenitic stainless steel test plate was prepared with a double-sided symmetrical V-V combined bevel using a beveling machine. The bevel angle is as follows: image 3 As shown; use a grinder (stainless steel grinding wheel) to grind and clean the groove and the 20mm range on both sides to remove oil and impurities; use oxyacetylene neutral flame to quickly clean the 304LN groove and the 30mm range on both sides of the base metal Heat to remove moisture; assemble the two test plates to be welded in pairs, with a blunt edge of 0mm and a gap of 3mm, using double-sided argon tungsten arc welding and double-sided filler wire for spot welding, welding materials for spot welding , The welding process is the same as that of double-sided argon tungsten arc welding and double-sided filler wire backing welding. After the spo...

Embodiment 2

[0065] Traditional submerged arc welding welding process, the steps are as follows:

[0066] (1) Preparation before welding

[0067] A 500×150×40mm (2 pieces) 304LN austenitic stainless steel test plate was prepared with a beveling machine to prepare an asymmetrical X-shaped bevel. The bevel angle is as follows: Figure 4 As shown; use a grinder (stainless steel grinding wheel) to grind and clean the groove and the 20mm range on both sides to remove oil and impurities; use oxyacetylene neutral flame to quickly clean the 304LN groove and the 30mm range on both sides of the base metal Heat to remove moisture; assemble the two test plates to be welded in pairs, the blunt edge is 4mm, the gap is 0mm, and E308L-16 welding rod is used for spot welding at both ends of the test plate.

[0068] (2) Welding

[0069]Submerged arc welding is used for bottom filling and cover welding, welding current is 400-450A, welding voltage is 29-33V, welding speed is 360-560mm / min, and line energy ...

Embodiment 3

[0075] Groove form and angle such as Figure 5 As shown, a symmetrical X-shaped groove is used. φ2.4mm double-sided tungsten argon arc welding double-sided filler wire is used for backing, the welding arc voltage is 12V, the welding current is 160A, the welding speed is 60-80mm / min, and the line energy is 14.4-19.2KJ / cm; The welding process is consistent with the first embodiment.

[0076] After testing, 2 of the 4 side bending samples are intact, and 2 have cracks, and the cracks are all at the bottom weld of argon arc welding. The length of a single crack is less than 3mm, which meets the qualified standard of NB / T 47014-2011, but the existing cracks also indicate that the double-sided argon arc welding must not use too much heat input, otherwise the shape of the weld will be reduced.

[0077] The weld structure of embodiment 1 is as figure 1 shown. The weld structure is composed of dendritic austenite and trace ferrite, which is the A solidification mode. The trace ferr...

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Abstract

The invention discloses a welding method for improving the ultra-low temperature toughness of 304LN austenitic stainless steel submerged arc welding joints. Arc welding is used for filling and covering welding, and the welding wire is ER317L Mod with a diameter of 3.2-4.0mm. The submerged arc welding wire model is ER317L modified type, which increases the lower and upper limits of Mn and Ni content, and is a fully austenitic welding wire. The groove adopts double-sided symmetrical V-V combined groove or double-sided symmetrical single V-single V combined groove to reduce the groove angle. During the welding process, the temperature between the passes is controlled below 80°C, and Ar+1~3%N is used as the shielding gas for argon arc welding. 2 . Using the above process can increase the impact energy of welded joints after heat treatment at ‑196 °C from the original dozen of joules to more than 50J.

Description

technical field [0001] The invention belongs to the field of welding technology and relates to a stainless steel welding technology, in particular to a welding method for improving the ultra-low temperature toughness of a 304LN austenitic stainless steel submerged arc welding joint. Background technique [0002] 304LN austenitic stainless steel has high strength and excellent ultra-low temperature toughness and plasticity, and has excellent corrosion resistance due to low carbon content. Compared with 304L, 0.1-0.16% N is added to improve the strength, especially in low temperature environment, and more importantly, it increases the resistance to pitting corrosion and crevice corrosion. 304LN was included in the national standard (GB / T4237-2015 and GB / T 3280-2015) for the first time in 2015. The grade is 022Cr19Ni10N. 304LN is often used as nuclear grade ultra-low temperature steel, and the service temperature is usually -196~-183℃ , the lowest temperature can reach -269℃. ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B23K9/167B23K9/18B23K9/32B24B9/04B23K103/04
CPCB23K9/167B23K9/182B23K9/32B24B9/04B23K2103/05
Inventor 闵晓峰邹大军潘伍覃吴梦先林德钰候华东郭则明祝强
Owner WUHAN YIYE STEEL STRUCTURE
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