JP6024865B2 - Laser arc hybrid weld cracking test method - Google Patents

Description

  The present invention relates to a laser arc hybrid weld cracking test method used for managing the quality of welded joints in large structures such as bridges and ships, particularly welded joints by laser arc hybrid welding.

Conventionally, as a weld crack test method used for managing the quality of the weld joint as described above, for example, there is a weld crack test method described in Patent Document 1.
In this weld crack test method, a set of test pieces are placed facing each other, and a gap setting block is interposed between them to form a root gap between the test pieces, and the test pieces are pressed against the gap setting block from both sides. Laser welding is performed between the test pieces in a held state, that is, in an externally constrained state.

  On the other hand, as a conventional weld crack test method that does not require external restraint, for example, there is a weld crack test method described in Non-Patent Document 1. This weld crack test method is an H-shaped constrained weld crack test method defined in JIS Z3159, and two slits are formed in the center so as to be parallel to each other. This is a test method using a test piece on which is formed, and is a weld crack test method for covering arc welding and gas shielded arc welding.

JP 2011-036911

JIS Z3159

  However, in the welding crack test method described in Patent Document 1 described above, the route gap between the test pieces can be strictly managed for laser welding, but at the time of laser welding, the test piece is not attached to the gap setting block. Since the pressing is performed from both sides, the degree of restraint may change depending on the pressing force of the test piece.

  On the other hand, the H-type constrained weld cracking test method described in Non-Patent Document 1 described above is a test method for covered arc welding and gas shielded arc welding, and therefore the root gap of the groove of the test piece is large. There is a problem that it cannot be used for the evaluation of weld cracks in laser arc hybrid welding in which a thin laser beam is irradiated, and it has been a conventional problem to solve these problems.

  The present invention has been made by paying attention to the above-described conventional problems, and can appropriately evaluate the weld cracking of laser arc hybrid welding. As a result, the quality of the welded joint portion in a large structure is controlled and It is an object of the present invention to provide a laser arc hybrid weld crack test method that can be guaranteed.

The invention according to claim 1 of the present invention is a laser arc hybrid weld cracking test method using a test piece in which a slit is formed at the center, and corresponds to the actual degree of restraint of the structure and this degree of restraint. The step of determining the outer dimensions and the slit length of the test piece reflecting the strain, and cutting out the plate material with the outer dimensions determined in this step, and the slit in the center of the cut out plate material in the step A step of producing the test piece formed with a determined length, a welding step of performing laser arc hybrid welding on the slit of the produced test piece, and the test piece after welding in this welding step A plurality of cross sections at positions where the value of the strain is relatively large based on the strain distribution obtained by analysis from the cross section of the test piece obtained in this cutting step. By calculating the average of a cross-sectional cracking rate of crack rates occurring in cross-section, the length of the plate thickness and the slit upon fixed without changing the welding material used in the laser arc hybrid welding the plate It is characterized by having a process of evaluating the risk of weld cracking by comparing the cross-sectional crack rates of the plurality of test pieces with different combinations of welding conditions. The laser arc hybrid weld cracking test method is used as a means for solving the above-described conventional problems.

  The laser arc hybrid weld cracking test method according to claim 2 of the present invention is configured such that the penetration depth of the weld metal into the slit of the test piece in the welding step is limited to half or less of the thickness of the test piece.

  In the laser arc hybrid weld cracking test method according to claim 3 of the present invention, the slit is formed between a pair of through holes formed in a central portion of the test piece, and the slit of the test piece in the welding step is formed. The laser arc hybrid welding is performed while avoiding the pair of through holes.

In the laser arc hybrid weld cracking test method according to the present invention, the slit at the center of the test piece is preferably formed by, for example, electric discharge machining, and the slit width is preferably 0.05 to 1.00 mm.
In the laser arc hybrid weld cracking test method according to the present invention, the outer dimensions of the test piece are, for example, a length, a width, and a plate thickness in the case of a rectangular shape, and these dimensions and slit length. Is obtained using FEM (finite element method) based on the actual degree of restraint of the structure and the strain corresponding to this degree of restraint. In addition, the shape of a test piece is not limited to a rectangle.

In the laser arc hybrid weld cracking test method according to the present invention, a test piece reflecting the degree of restraint measured in an actual structure and the strain corresponding to the degree of restraint is manufactured, and a laser is applied to the slit of the test piece. Arc hybrid welding is performed, and the average crack rate that occurs at the weld joint cross section is calculated at that time, so the risk of weld cracking can be evaluated more closely, and laser arc hybrid welding is performed. It is possible to feed back a combination of steel, weld metal, and welding conditions to an actual structure that is difficult to cause weld cracks.

  At this time, if the penetration depth of the weld metal with respect to the slit of the test piece in the welding process is limited to less than half of the thickness of the test piece, it is possible to create a condition where a weld crack is likely to occur. For example, when it is formed by electric discharge machining, it is possible to create a more realistic welding situation by performing laser arc hybrid welding while avoiding the through holes formed at both ends of the slit.

  The laser arc hybrid weld cracking test method according to the present invention has the above-described configuration, so that it is possible to appropriately and more accurately evaluate the weld crack of laser arc hybrid welding, and therefore, a welded joint in a large structure. This provides an excellent effect that the quality of the parts can be managed and guaranteed.

It is plane | planar explanatory drawing (a) and front explanatory drawing (b) of the test piece used for the laser arc hybrid welding crack test which concerns on one Example of this invention. It is plane explanatory drawing (a) of the state which performed the laser arc hybrid welding with respect to the test piece shown in FIG. 1, and plane explanatory drawing (b) which specifies the cutting location after welding. It is a graph showing the relationship between the plate | board thickness of the test piece shown in FIG. 1, a restraint degree, and the distortion | strain corresponding to this restraint degree. It is a graph showing the weld crack test result with respect to the test piece shown in FIG.

Hereinafter, the present invention will be described with reference to the drawings.
1 and 2 show an embodiment of a laser arc hybrid weld cracking test method according to the present invention.

This laser arc hybrid weld crack test method is a laser arc hybrid weld crack test method using a test piece 1 having a slit 4, as shown in FIG. A step of determining the external dimensions of the test piece 1 and the length of the slit 4 reflecting the corresponding strain, and cutting out the plate material with the external dimensions determined in this step, and determining the slit 4 at the center of the cut plate material and a step of making a test strip 1 forms the shape length that is.

The test piece 1 has a pair of through holes 3 and 3 formed at the center of a test piece main body 2 made of a rectangular steel plate, and the slit 4 is formed between these through holes 3 and 3. The test piece body 2 is located at the center in the longitudinal direction.
The external dimensions of the rectangular test piece 1 are a length L, a width B, and a plate thickness t. These dimensions L, B, t and the length Ls of the slit 4 are the degree of restraint of the actual structure. And based on the strain corresponding to this degree of restriction, it is obtained using FEM (finite element method).

  In this case, the slit 4 is formed by electric discharge machining, the width W of the slit 4 is 0.05 to 1.0 mm, and the diameters of the through holes 3 and 3 for passing the wire are about 6 mm.

  Thus, the test piece 1 is manufactured by cutting out from the steel plate with the outer dimensions L, B, and t determined by FEM, and forming the slit 4 with the determined length Ls at the center of the cut out plate material. The

In addition, as shown in FIG. 2A, this laser arc hybrid weld cracking test method includes a welding process in which laser arc hybrid welding is performed on the slit 4 of the manufactured test piece 1, and FIG. Thus, the process of cutting the weld bead 5 in the test piece 1 after welding at a plurality of locations, and calculating the average of the respective crack rates occurring in the plurality of cross sections of the test piece 1 obtained in this cutting process, It has a process to evaluate the risk of cracking. At this time, from the strain distribution in the weld bead 5 obtained by the analysis, a plurality of cross sections at positions where the strain value is relatively large are selected to calculate the average crack rate.

  In this embodiment, the weld metal penetration depth with respect to the slit 4 of the test piece 1 in the welding process is limited to half or less of the plate thickness t of the test piece 1 to create a condition in which a weld crack is likely to occur. It is made to be able to.

  In addition, by avoiding the through holes 3 and 3 located at both ends of the slit 4 and performing laser arc hybrid welding, heat input through the through holes 3 is prevented and a welding situation that is more realistic is achieved. It can be produced.

As described above, in the laser arc hybrid weld cracking test method of this embodiment described above, the test piece 1 reflecting the degree of restraint measured in the actual structure and the strain corresponding to this degree of restraint is manufactured, and this test is performed. Since the laser arc hybrid welding is performed on the slit 4 of the piece 1 and the average of the crack rate generated in the weld bead 5 is calculated at that time, the risk of weld cracking can be evaluated (corresponding to the degree of restraint) It is possible to evaluate more precisely by reflecting the strain to be applied), and it is difficult to generate weld cracks when laser arc hybrid welding is performed. The combination of steel, welding material, and welding conditions is applied to the actual structure. You can get feedback.

  FIG. 3 is a graph illustrating the outer dimensions of the test piece 1 and the lengths of the slits 4 reflecting the actual degree of restraint of the structure and the restraint strain corresponding to the degree of restraint. In the test piece 1 (test piece a, test piece b, test piece c) used in the laser arc hybrid weld cracking test method, the degree of restraint increases as the thickness t increases, that is, the degree of restraint is quantified. In addition, it is possible to evaluate the weld crack more precisely if it is understood that the change in the restraint strain deviates from the change in the restraint degree according to the change in the plate thickness as in the test piece a. Will get.

  FIG. 4 shows a weld crack test result for the test piece 1. As shown in FIG. 4, the thickness of the test piece a (width B = 150 mm, length L = 200 mm, slit length Ls = 80 mm) manufactured corresponding to a constraint Rp of about 30000 N / mm · mm is 25 mm. In this case, it can be seen that both the combination of the steel material Sb and the welding material Y and the combination of the steel material Sa and the welding material X have a high cross-sectional crack rate, and the combination of the steel material Sa and the welding material Y has a low cross-sectional crack rate.

  In addition, when the plate thickness of the test piece a to be manufactured corresponding to the constraint degree Rp of about 14000 N / mm · mm is 12 mm, the combination of the steel material Sb and the welding material Y has a very high cross-sectional crack rate, and the steel material Sa It can be seen that the combination of the welding material X and the steel material Sa and the welding material Y all have low cross-sectional crack rates.

On the other hand, when the plate thickness of the test piece b (width B = 150 mm, length L = 200 mm, slit length Ls = 120 mm) manufactured corresponding to the constraint degree Rp of about 14000 N / mm · mm is 25 mm, the steel material It can be seen that the combination of Sa and welding material Y has a low cross-sectional crack rate.
Here, when the plate thickness of the test piece a to be manufactured corresponding to the restraint degree Rp of about 14000 N / mm · mm is 12 mm, although the cross-section crack ratio is very high in the combination of the steel material Sb and the welding material Y, If the slit length Ls is set to 120 mm as in the case of the test piece b and the restraint degree is lowered, it can be seen that even when the steel material Sb and the welding material Y are combined, the cross-sectional crack rate decreases.

  As described above, if the steel materials Sa and Sb used for the test pieces a and b, the plate thickness t of the test pieces a and b, and the welding materials X and Y are appropriately selected and determined and fed back to the actual structure, a large structure The quality of the welded joint part in the object can be managed and guaranteed.

  The configuration of the laser arc hybrid weld crack test method according to the present invention is not limited to the configuration of the above-described embodiment.

DESCRIPTION OF SYMBOLS 1 Test piece 2 Test piece main body 3 Through-hole 4 Slit 5 Weld bead B Width L Length Ls Slit length t Plate thickness W Slit width

Claims (3)

A laser arc hybrid weld cracking test method using a test piece having a slit formed in the center,
Determining the outer dimensions of the test piece and the slit length reflecting the degree of constraint of the actual structure and the strain corresponding to the degree of constraint;
Cutting out the plate material with the outer dimensions determined in this step, and forming the test piece by forming the slit with the length determined in the step in the central portion of the cut plate material;
A welding process in which laser arc hybrid welding is performed on the slit of the manufactured test piece;
Cutting the test piece after welding in this welding step at a plurality of locations;
A cross section that is an average of the crack rates occurring in the cross section by selecting a plurality of cross sections at positions where the strain value is relatively large based on the strain distribution obtained by analysis from the cross section of the test piece obtained in this cutting step A plurality of the test pieces in which the crack rate is calculated, the plate thickness and the slit length are fixed without being changed, and the combination of the plate material, the welding material used in the laser arc hybrid welding, and the welding conditions are changed. A laser arc hybrid weld cracking test method characterized by comprising a step of evaluating the risk of weld cracking by comparing the cross-section crack ratios of each other.   2. The laser arc hybrid weld cracking test method according to claim 1, wherein a penetration depth of the weld metal into the slit of the test piece in the welding step is limited to half or less of a thickness of the test piece.   The slit is formed between a pair of through holes formed in the center of the test piece, and laser arc hybrid welding to the slit of the test piece in the welding process is performed avoiding the pair of through holes. The laser arc hybrid weld cracking test method according to claim 1 or 2.

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