CN101402159B - A test device and test method for weldability of marine steel - Google Patents

Abstract

The invention discloses a test device and a test method for the weldability of marine steel, belonging to the technical field of material connection. The test device consists of a test plate and a stiffener welded along the width direction of the test plate and perpendicular to the test plate. The steps of the test method are: first select the material to make the test device; then paste the ceramic liner on the back of the test plate; weld the welding gap set by the test plate according to the set welding specification parameters; place it at room temperature for 24 hours after welding, Then use the coloring flaw detection method to inspect the test weld. In the present invention, because the size of the test plate of the test device is large, it is closer to the actual situation than the test plate size of the commonly used weldability test method. The ribs simulate the structure of the ship, with small spacing and high rigidity. Since the ceramic liner is pasted on the back of the test plate of the test device, the welding gap can be set, so it can completely simulate the real situation of ship plate welding. It has practicality and popularization and application value.

Description

A test device and test method for weldability of marine steel

technical field

The invention belongs to the technical field of metal material connection. The invention relates to a test of weldability of steel, and more specifically relates to a test device and a test method of weldability of marine steel.

Background technique

The definition of metal weldability is whether the metal can adapt to the welding process to form a complete welded joint with certain performance. This has two meanings. One is that the metal material cannot have cracks (cold cracks, hot cracks), pores and other defects that affect the integrity of the metal after welding. This is usually verified by a weldability test. The second is that after the metal material is welded, the performance of the weld seam, heat-affected zone and other areas cannot be significantly reduced, which will affect future use. This is usually verified by testing mechanical properties.

There are many types of metals, their properties are also very different, and the mechanism of defects is also different, so each weldability test method has its applicable range. So far, welding workers at home and abroad have invented nearly a hundred welding test methods for different materials, different application occasions and specific welding defects that need to be tested. For example, the commonly used weldability test methods are: 1) Inclined Y-groove welding crack test method; it is mainly applicable to the cold crack sensitivity assessment of the welding heat-affected zone of carbon steel and low-alloy high-strength steel. 2) Plug test; the purpose is to evaluate the cold crack sensitivity of steel welding heat-affected zone. This is a quantitative method with less steel consumption and stable and reliable test results. It can also be used to determine reheat crack sensitivity and lamellar tear sensitivity . 3) Pressure plate butt welding crack test method (Fisco test); the purpose is to evaluate the thermal crack sensitivity (proposed by Swiss welding engineers). 4) Adjustable restraint crack test method; the purpose is to evaluate the thermal crack sensitivity (proposed by American welding expert Savage in 1965). 5) Rigid fixed butt joint crack test (Badong test); the purpose is to evaluate the sensitivity of hot cracks and cold cracks (proposed by the Ukrainian Padang Welding Institute). And tensile restraint crack test (TRC); rigid restraint crack test (RRC); window restraint crack test and so on.

With the continuous development of shipbuilding technology, the tonnage of shipbuilding has also grown from the largest 10,000-ton ship in the 1960s to today's 500,000-ton oil tanker. The length of its ships has grown from tens of meters to nearly 400 meters today. This brings new problems. The wavelength of the waves in the Pacific Ocean is usually about 200 meters. Ships less than 200 meters will bump up and down in the wind and waves, and sometimes there is a danger of sinking the ship. When the length of the ship is greater than 200 meters, the ups and downs will be reduced a lot, and the safety of sailing in wind and waves is also higher. But at this time, new requirements are put forward for the construction quality of the ship. Because the length of the ship is greater than the length of the waves, there are often two waves acting on the hull at the same time, which is a typical three-point bending in mechanics. If there is a welding defect at the point of maximum force, it is easy to cause damage and cause a major accident. In recent years, there have been reports of 175,000-ton ships breaking in half. The weldability of steel used in large ships, such as DH32 and DH36, is generally good, and almost no welding defects can be detected by the above-mentioned existing conventional weldability test methods. However, during the welding process of the medium and thick plate structure in the shipyard, longitudinal cracks are often found in the bottom weld, and transverse cracks are also found in individual structures with a lot of restraint, and the cracking position is not fixed, and there are cracks on the surface as well as on the surface. Cracks below 3-4mm. The reason for this problem is that the existing weldability test methods do not truly simulate the actual situation of shipbuilding. For example, when welding in shipbuilding, ceramic liners are pasted on the back of the steel plate to achieve the purpose of single-sided welding and double-sided forming. However, all weldability test methods do not have ceramic liners. In addition, all current weldability test methods have a weld gap of 2 to 3 mm. The shipyard’s regulation is 6mm, and the construction site often reaches 10mm, and some even reach 18mm. The welding current of the existing welding test method is usually 180-220A, but in fact, the shipyard often increases the welding current to 250A or even 280A in order to catch up with the schedule.

The above situation shows that the existing weldability test method cannot truly reflect the actual situation of ship construction, and the welding materials and marine steel plates that have no problems after using the existing weldability test method will still have defects during actual shipbuilding , which brings a lot of repair work to the manufacturer, and also brings great hidden dangers to the safe navigation of the ship. Therefore, it is necessary to re-focus on the actual situation of shipyard production, combined with the habits of shipyard production, to formulate a weldability test method and welding test device that conform to the actual situation of shipyard production, truly reflect the structure, stress, and welding state of actual production, and serve as a reference for shipbuilding. Provide a safe and reliable acceptance criteria.

Contents of the invention

Technical problem: The purpose of the present invention is to overcome the existing problems and deficiencies in the prior art, solve the technical problem of being able to truly simulate the weldability test of marine steel, and provide a test device and test method for the weldability of marine steel.

Technical scheme: in order to achieve above-mentioned purpose, the technical scheme that the present invention solves its technical problem is:

A test device for the weldability of marine steel, consisting of a test plate and reinforcing ribs welded along the width direction of the test plate and perpendicular to the test plate, wherein the test plates are 2 pieces; the reinforcing ribs are 4 strips; the opposite edges of adjacent test panels are respectively processed with a slope, and there is a welding gap between two adjacent test panels and a V-shaped notch of 45 ^{± 5o} is formed; the side of the rib corresponding to the V-shaped notch is opened There is a gap; the two adjacent test plates are also pasted with a ceramic liner on the side of the gap corresponding to the reinforcing rib.

The dimensions of the above-mentioned test panels are 700-1000mm in length and 260-300mm in width; the opposite edges of adjacent test panels are processed with a slope of 22.5 ^{± 2.5o} .

The dimensions of the above-mentioned reinforcing ribs are 520-600 mm in length, 70-200 mm in width, and 8-20 mm in thickness; the gaps described above are rectangular, and the dimensions are 40-60 mm in length and 10-20 mm in depth.

The distance between two adjacent ribs mentioned above is 200-300 mm; the height of the welding leg is 0.7 times the thickness of the rib plate.

Another technical scheme that the present invention solves its technical problem is:

A test method for the weldability of marine steel products, comprising the steps of:

(1) Select the steel plate consistent with the actual production for cutting and blanking, and process the groove with a slope of 22.5 ^{± 2.5o} and the rectangular notch with a length of 40-60mm and a depth of 10-20mm for the test plate and the reinforcing rib respectively;

(2) Assemble the 2 test panels, reserve the set welding gap, and weld the 4 ribs evenly spaced on the back of the test panel on both sides, and the height of the welding foot is 0.7 times the thickness of the rib plate;

(3) Paste a ceramic liner on the back of the test plate;

(4) Weld the welding gap set by the test plate according to the set welding specification parameters;

(5) Place it at room temperature for 24 hours after welding, and inspect the test weld by coloring flaw detection method.

Wherein, the welding described in the above step (4) is performed by pure CO ₂ gas shielded welding, and the welding material is a flux cored wire with a diameter of 1.2mm.

Beneficial effects: the beneficial effects and advantages of a test device and test method for the weldability of marine steel products of the present invention are mainly reflected in:

One is that the gap of the welding groove of the test plate of the test device can be set, so the difference in weldability under different gaps can be evaluated;

The second is to paste a ceramic liner on the back of the test plate of the test device, which can completely simulate the real situation of ship steel plate welding;

The third is that the size of the test plate of the test device is large, and the spacing of the reinforcing ribs is small, so the overall restraint is large. Welding materials and processes that do not produce cracks under the conditions of the existing conventional weldability test methods can produce cracks in this test device and test method, and its laws are completely consistent with the actual situation, which can truly simulate the actual production process. Weldability of marine steels.

Description of drawings

Fig. 1 is the front view of the present invention,

Fig. 2 is a side view of the present invention,

In the figure: 1. Welding test plate, 2. Rib, 3. Ceramic liner.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

Shown in Fig. 1 and Fig. 2, the test device of the weldability of a kind of marine steel of the present invention is made up of two test plates 1 and the stiffener 2 that is welded on test plate, the edge processing of every test plate 1 has 22.5 ^± With a slope of ^2.5o , two test panels 1 form a V-shaped notch 4 with a welding gap of 45 ^{± 5o} . There is a rectangular notch 5 with a depth of 10-20 mm and a width of 40-60 mm in the middle of the reinforcing rib 2. A ceramic liner 3 is pasted on the back of the test plate corresponding to the notch 5 of the reinforcing rib. The reinforcing rib is welded on the back of the test plate and is Double-sided welding and fixing; 4 reinforcing ribs 2 are arranged in the length direction of the entire weldability test device, the spacing is 200-300mm, the direction of the reinforcing ribs 2 is perpendicular to the direction of the weld, and the height of the welding leg is 0.7 times the thickness of the reinforcing rib plate.

The test procedure of the weldability of a kind of marine steel of the present invention is:

(1) Select the thickness of the plate consistent with the actual production. The test plate is cut and blanked according to the length of 700-1000mm; the width is 260-300mm; Process the groove with a slope of 22.5 ^{± 2.5o} and the rectangular notch with a length of 40-60mm and a depth of 10-20mm for the test plate and the rib respectively;

(2) Make a pair of the two test panels that were cut out, set the welding gap to 3-18 mm, and weld four reinforcing ribs 2 on the back of the test panel 1 with a spacing of 200-300 mm. The height of the welding foot is 0.7 times the thickness of the reinforcement rib 2, and double-sided welding is adopted;

(3) Paste a ceramic liner on the back of the test plate 1;

(4) _CO2 gas shielded welding is used to weld the welding gap of the paired test plates, and the welding material is flux-cored wire with a diameter of 1.2mm or copper-plated solid wire; among them, the welding specification parameters are: welding current 250A, The welding voltage is 27V, and the welding speed is 8-25mm/min. When the welding gap is 3mm, the welding speed is 25mm/min; when the welding gap is 18mm, the welding speed is 8mm/min. The welding gap corresponding to other gaps can be selected by interpolation. The welding method can be selected according to the size of the welding gap, and the swing method can be selected to ensure that both sides of the welding groove have good fusion, and the root of the groove can ensure penetration, so as to achieve single-sided welding and double-sided forming;

(5) Regardless of the thickness of the plate, only one test pass is to be welded. Place it at room temperature for 24 hours after welding, and check the test weld. The inspection is carried out by coloring flaw detection method.

The following are application examples of the present invention:

In the application example of the present invention, DH36 low-alloy high-strength steel was used as the steel type for the test. Six groups of steel plates with the same specification of 700mm×260mm×26mm were used in the experiment, and TWE produced by Tiantai Welding Material (Kunshan) Co., Ltd. was selected as the welding material. -711 flux-cored welding wire, and the welding machine adopts the _CO2 welding machine produced by Tangshan Panasonic Company. In the experiment, the same welder uses the same welding equipment to carry out welding under different welding parameters and gap conditions. A series of data are shown in Table 1. Photographs of post-weld testing.

Table 1 Data obtained by different welding process parameters

After comparing and analyzing the data in Table 1 and the photo distribution characteristics of the post-weld flaw detection, it is concluded that the welding gap is from 3mm to 18mm under the actual production welding current of 250A and welding voltage of 27V using the weldability test method of the present invention. , different welding parameters produce different degrees of welding cracks, and the welding cracks of 3mm are the most obvious; 6mm has no welding cracks, which is the welding gap specified by the shipyard; 9mm welding cracks have begun to increase, 12mm has many and long cracks, and 15mm It has been reduced, and the 18mm has almost no cracks. This rule is very consistent with the actual situation of welding production in shipyards, indicating that this test method truly reproduces the actual conditions of welding in shipyards. Therefore, the weldability evaluation of marine steel plates and welding materials can be carried out by adopting a test device and test method for the weldability of marine steel products of the present invention.

Claims (7)

1. the experimental rig of a weldability for rolled steel for vessel, it is characterized in that: this experimental rig is formed by test plate (panel) (1) with along test plate (panel) (1) width and with the perpendicular reinforcement that is welded to connect of this test plate (panel) (2), wherein said test plate (panel) (1) is 2, and described reinforcement (2) is 4; The opposite edges of adjacent two test plate (panel)s (1) are processed with a gradient respectively, leave welded gaps between two test plate (panel)s and form 45 ± 5 V-arrangement shape recesses (4) of spending; The one side of described reinforcement (2) corresponding V-arrangement shape recess (4) position offers a breach (5); Also be pasted with ceramic substrate (3) on the one side of the breach (5) of the described two corresponding reinforcements of adjacent test plate (panel) (1) (2).

2. the experimental rig of a kind of weldability for rolled steel for vessel according to claim 1 is characterized in that described breach (5) is rectangle, and dimensions is long 40～60mm, dark 10～20mm.

3. the experimental rig of a kind of weldability for rolled steel for vessel according to claim 1 is characterized in that: the dimensions of described test plate (panel) (1) is long 700～1000mm, wide 260～300mm; The gradient that the opposite edges of adjacent test plate (panel) (1) are processed with respectively is 22.5 ± 2.5 °.

4. the experimental rig of a kind of weldability for rolled steel for vessel according to claim 1 is characterized in that: the dimensions of described reinforcement (2) is long 520～600mm, wide 70～200mm, and thick 8～20mm, two adjacent spacings are 200～300mm.

5. the experimental rig of a kind of weldability for rolled steel for vessel according to claim 2 is characterized in that: described test plate (panel) (1) is that with being welded to connect of reinforcement (2) welding by both sides, foot welding height are 0.7 times of reinforcement (2) thickness of slab.

6. the test method of the experimental rig of a kind of weldability for rolled steel for vessel according to claim 1, it is characterized in that: this test method comprises the steps:

(1) selecting the steel plate consistent with actual production to carry out cutting stock, is 22.5 to the test plate (panel) processing gradient ^{± 2.5}° groove and reinforcement added section chief 40～60mm, the rectangle breach of dark 10～20mm;

(2) 2 test plate (panel) groups are right, as reserve to set welded gaps, simultaneously with 4 reinforcement spacings in uniform way welding by both sides be connected on the back side of test plate (panel), foot welding height is 0.7 times of reinforcement thickness of slab;

(3) paste ceramic substrate at the back side of test plate (panel);

(4) be welding current 250A by the welding variables of setting, weldingvoltage 27V, speed of welding 8～25mm/min, the welded gaps that test plate (panel) is set is that 3～18mm welds;

(5) postwelding normal temperature was placed 24 hours down, adopted the dye penetrant inspection method that pilot seam is checked.

7. the test method of the experimental rig of a kind of weldability for rolled steel for vessel according to claim 6 is characterized in that: the described pure CO of employing that is welded as of described step (4) ₂Gas shielded arc welding, welding material are the flux-cored wire of selecting diameter 1.2mm for use.

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