rus
Issue #3/2025
M. V. Kuznetsov, M. V. Larin, D. A. Kuznetsova, A. A. Popovich
Aluation of Residual Deformations of a Welded Joint Generated by Various Welding Methods
Aluation of Residual Deformations of a Welded Joint Generated by Various Welding Methods
DOI: 10.22184/1993-7296.FRos.2025.19.3.192.209
This paper presents the comparison results of laser and arc welding methods. The modes for laser welding, hybrid laser-arc welding and laser welding with filler wire for the St3 plates with the thickness of 10 mm were developed. Three test joints were welded by each welding method using the developed modes. The metallographic studies were conducted demonstrating stable formation of the welded joint and absence of internal defects. The residual deformations were assessed for the following types of welding: laser welding, hybrid laser-arc welding, laser welding with filler wire, single-sided and double-sided manual arc welding, single-sided and double-sided mechanized welding in the active gases and mixtures. The test samples for each welding type were analyzed in terms of the level of residual deformations after welding by comparing geometric dimensions and using the 3D scanning procedure. A comparative technical and economic analysis of welding methods was performed.
This paper presents the comparison results of laser and arc welding methods. The modes for laser welding, hybrid laser-arc welding and laser welding with filler wire for the St3 plates with the thickness of 10 mm were developed. Three test joints were welded by each welding method using the developed modes. The metallographic studies were conducted demonstrating stable formation of the welded joint and absence of internal defects. The residual deformations were assessed for the following types of welding: laser welding, hybrid laser-arc welding, laser welding with filler wire, single-sided and double-sided manual arc welding, single-sided and double-sided mechanized welding in the active gases and mixtures. The test samples for each welding type were analyzed in terms of the level of residual deformations after welding by comparing geometric dimensions and using the 3D scanning procedure. A comparative technical and economic analysis of welding methods was performed.
Теги: 3d scanning 3d сканирование hybrid laser-arc welding laser-beam welding laser welding with filler wire residual deformations гибридная лазерно-дуговая сварка лазерная сварка лазерная сварка с присадочной проволокой остаточные деформации
Evaluation of Residual Deformations of a Welded Joint Generated by Various Welding Methods
M. V. Kuznetsov, M. V. Larin, D. A. Kuznetsova, A. A. Popovich
Peter the Great St. Petersburg Polytechnic University, Saint-Petersburg, Russia
This paper presents the comparison results of laser and arc welding methods. The modes for laser welding, hybrid laser-arc welding and laser welding with filler wire for the St3 plates with the thickness of 10 mm were developed. Three test joints were welded by each welding method using the developed modes. The metallographic studies were conducted demonstrating stable formation of the welded joint and absence of internal defects. The residual deformations were assessed for the following types of welding: laser welding, hybrid laser-arc welding, laser welding with filler wire, single-sided and double-sided manual arc welding, single-sided and double-sided mechanized welding in the active gases and mixtures. The test samples for each welding type were analyzed in terms of the level of residual deformations after welding by comparing geometric dimensions and using the 3D scanning procedure. A comparative technical and economic analysis of welding methods was performed.
Keywords: laser-beam welding, hybrid laser-arc welding, laser welding with filler wire, residual deformations, 3D scanning
Article received: April 07, 2025
Article accepted: April 28, 2025
INTRODUCTION
In the Russian Federation, the issue of innovative domestic industrial development is extremely relevant. The welding and related technologies play an important role in the creation of innovative products: up to 50% of the gross output in heavy engineering is obtained using the welding and related technologies, and up to 67% of rolled metal products are used to produce the welded structures [1].
As a rule, the welded metal structures are manufactured using the manual arc welding (MMA), mechanized semiautomatic welding in gases and mixtures (MSW) or submerged arc welding methods. When preparing the parts to be welded, it is necessary to prepare the fusion edges, including chamfering, usually with a chamfer angle of up to 60 degrees. Then, welding is performed with the weld deseaming after each pass. For example, when welding the samples with the thickness of 60 mm using the MMA method, up to 74 passes can be made [2]. This is a rather labor-intensive process, leading to the decreased performance of the final product manufacturing process, an increased amount of consumed power, welding materials and an enhanced likelihood of internal defects.
Another issue during the welded joint formation is welding deformations. First of all, any deformations that occur as a result of welding complicate the assembly process for the large-sized structures consisting of individual welded blocks, units and sections, worsen the appearance, operational performance of the structure and require the introduction of additional operations to eliminate welding deformations, such as subsequent heat treatment, preliminary bending, expansion joints, elimination of the previously introduced allowance of up to several tens of millimeters for joining the components, etc.
Due to the peculiarities of arc welding processes, their use in the up-to-date production processes often does not meet the requirements, primarily in terms of performance and energy efficiency.
The most promising welding methods that meet the above requirements include laser welding (LW) [3, 4], hybrid laser-arc welding (HLAW) [5–7] and laser welding with filler wire (LBW-W) [8, 9] that have a number of advantages over the conventional methods, including local impact, minimal energy input, minimal width of the heat-affected zone (HAZ) and deformations.
Within the framework of this paper, the task was set to conduct a comprehensive study of the influence of various welding methods on the level of residual deformations, energy contribution and width of the heat-affected zone (HAZ) of the obtained welded joints, as well as on the economic efficiency of each method application.
1. Experimental and research equipment
1.1. Experimental Equipment
The development of the LW, HLAW and LBW-W modes, as well as welding of the test samples, was performed using a robotic process system for hybrid laser-arc welding (RPS HLAW) in the research laboratory “Laser and Additive Technologies” of the Institute of Mechanical Engineering of Materials and Transport in Peter the Great St. Petersburg Polytechnic University (Fig. 1). Welding of the samples by the MMA and MSW methods was performed by the employees of ECM LLC (Engineering. Construction. Maintenance).
For safety purposes, the RPS HLAW is made in a protective cabin, preventing the dangerous effect of reflected laser radiation. The cabin is equipped with the windows with light filters, CCTV cameras and ventilation. The composition of the RPS HLAW is given in Table 1. The laser source parameters are given in Table 2. The beam caustic is shown in Fig. 2.
1.2. Research Equipment
The formation quality of welded joints was studied using the transverse macrosections made by a PRESI MECATECH 234 automatic grinding and polishing machine. The metallographic studies of the samples were performed using an inverted optical microscope IM7400L (Meiji Techno, Japan). The 3D scanning procedure for the samples before and after welding was performed using a 3D scanner ScanTech TrackScan P42.
2. Welding materials
The samples (plates) with the dimensions of 300 × 100 × 10 mm, made of steel grade St3 were used in the work. The samples were prepared for each welding method: for MMA and MSW according to GOST 5264-80-C25 (Fig. 3). For MMA, an E50A electrode was used according to GOST 9467-75, for MSW, an OK AristoRod 12/63 ∅1.2 mm welding wire was used.
The cuts for the LW, HLAW and LBW-W methods are shown in Fig. 3. To measure the residual deformations, three holes with a diameter of 3 mm were made in the plates. The plate drawing is shown in Fig. 5.
The fusion edges of the plates and an area with the width of 1 cm from the edges were pre-cleaned using an angle grinder to a metallic shine and degreased with acetone. Prior to welding, the plates were placed in a rigid fixture and fixed (Fig. 6).
In the case of HLAW and LBW-W, the POWER PIPE 60R welding wire with a diameter of 1.2 mm was used. The chemical composition of the wire is given in Table 3.
To provide local protection of the welding pool, a mixture of Ar/СО2 gases was applied in the ratio of 80%/20%.
3. Experiment
When developing the LW, HLAW and LBW-W technologies, the single full-penetration welds were made in various modes. The criteria for determining the optimal welding mode were as follows: through penetration, stable and high-quality bead formation on the front and back sides, and absence of any defects. When developing the modes, the main process parameters were varied: laser radiation power (PL) in the range from 2000 W to 10000 W; welding speed (V) from 20 mm/sec to 30 mm/sec; changes in the distance from the laser head to the welded surface (dF) from –4 mm to +1 mm; wire feed speed (Vwf) from 0.6 m/min to 1.2 m/min; shielding gas consumption (R) from 25 l/min to 50 l/min. In the selected mode, three test joints were welded by each method in order to study any residual deformations. Prior to welding, the plates were tacked from the back side of the joint in the welding mode.
Before the tack welds and after welding, for subsequent analysis of deformations, the distances S1, S2, S3, S4, S5 were measured according to the diagram shown in Fig. 7.
4. Welding of samples
4.1. Welding of Samples by Arc Methods
The test samples manufactured by the MMA and MSW methods were formed respectively by welding from one side (MMA1 and MSW1) in 3 passes and welding from two sides (MMA2 and MSW2) in 4 passes. The end views of the welded samples are shown in Fig.8.
4.2. Welding of Samples by Laser Methods
The parameters of modes in which the test samples were welded using the LW, HLAW and LBW-W methods are given in Table 4. Fig. 9 shows the end view of the welded samples.
5. Metallographic studies
During the metallographic studies, the transverse macrosections of sampled welded joints for each welding method were prepared (Fig. 10). The photographs of such macrostructures show no internal defects (except for MSW1), such as any pores, cracks and lack of penetration. A defect in the form of lack of penetration with the length of about 2 mm and width of up to 0.5 mm was found in the transverse macrosection of MSW1. According to the requirements of the ultrasonic inspection (STO 00220256–005–2005) imposed during the weld inspection, this defect is acceptable.
Based on the macrosection analysis results, it was noted that in the case of LW and HLAW, the HAZ width was 7–8 times smaller compared to the HAZ width of the welds obtained by the MSW and MMA methods and amounted to 0.32 mm and 0.4 mm, respectively.
As a result of the microstructural control of the studied samples (LW; HLAW; LBW-W; MMA1; MMA2; MSW1; MSW2), the defects in the form of numerous pores were found. These defects may be related to the steel production technology, or to the availability of non-metallic inclusions, as well as gas porosity occurred during the recrystallization process.
Fig. 11 shows the base metal microstructure of the samples under study. It is evident that the metal structure is uniform and even, without any signs of banding. The structure is a ferrite and pearlite mixture, with a ferrite to pearlite ratio of 35/65% according to scale 7 in GOST 8233-56.
The grain size analysis shows that the value for all samples corresponds to 7–8 points, and near the weld seam – 8–9 points according to scale 1 in GOST 5639-82. Fig. 12 shows the microstructure of welds for each welding method.
The microstructural analysis of the welded joint, including the weld zone, fusion zone and heat-affected zone, is given in Table 5.
6. Analysis of residual deformations and feasibility study of welding methods
6.1. Results of Residual Deformation Analysis Using the Hole Spacing Method
The residual deformations for laser welding methods were assessed by comparing the sizes S1, S2, S3, S4, S5 (Fig. 10) obtained before and after welding. The measurements were performed using ШЦ‑1 from the front side of the seam for all three test joints obtained by the LW, HLAW, LBW-W methods, after which the arithmetic mean value was determined for each size.
Table 6 shows the measurement results and also indicates the difference between these values. According to the data (Table 6), the smallest residual deformations were observed in the case of HLAW and LW: in the longitudinal section – 0.21 mm and 0.26 mm, respectively; in the transverse section, the deformations were not registered.
The maximum values of deformations were observed for LBW-W: in the longitudinal direction – 0.79 mm; in the transverse direction – 0.25 mm. The comparable deformations in the case of MSW2: 0.81 mm and 0.32 mm, respectively. In order to verify the measurement results, the residual deformation measurements were additionally performed using the 3D scanning method.
6.2. Analysis of Residual Deformations by the 3D Scanning Method
To confirm the analysis results for the welded joint deformations (Table 5) generated using the laser welding methods at the Research Laboratory “Laser and Additive Technologies” of the Institute of Mechanical Engineering, Materials and Transport, Peter the Great St. Petersburg Polytechnic University, all test samples were scanned after welding by a 3D scanner TrackScan P42. In the GeoMagic Control X program the scanned models of samples were compared with a reference sample without any deformations, after which a deviation map was prepared (Fig. 12).
The results of deviation measurements at 6 points by the module are given in Table 7. The measurement scheme at 6 points is shown in Fig. 14.
Based on the calculation results, the maximum deviations were registered for LBW-W and amounted to 0.87 mm. The minimum deviations were registered for HLAW (0.3 mm) and LW (0.38 mm) that can be justified by the minimum rate of energy input and the HAZ width.
6.3. Feasibility Study of Welding Methods
A comparative efficiency analysis of the welding methods was performed using the transverse macrosections of welded joints.
The analysis results showed that the rate of energy input for LW and HLAW was 6.5 times lower than this indicator for LBW-W and up to 15 times lower than for MMA and MSW. The welding wire consumption when comparing the similar welding methods was also 9.5 times lower than for LBW-W and up to 14 times lower than for the arc welding methods. The shielding gas consumption was 33.3 times lower than for LBW-W and up to 32 times lower than for the arc welding methods. Fig. 15 shows a diagram comparing welding methods as a percentage (%) of the maximum indicator value.
CONCLUSION
Based on the comprehensive study results related to the influence of various welding methods on the level of residual deformations, energy contribution and width of the heat-affected zone (HAZ) of the obtained welded joints, as well as on economic efficiency, the following was established:
the minimum welding deformations were registered in the case of ALHW (0.21–0.3 mm), as well as LW, where the deformations were 4 times lower than in the case of LBW-W;
the smallest HAZ width was registered for LW and HLAW (0.32 mm and 0.4 mm, respectively) that was up to 8 times less than for MMA and MSW;
the rate of energy input for LW and HLAW was 6.5 times lower compared to the LBW-W and up to 15 times lower compared to MMA and MSW;
the welding wire consumption when comparing the similar welding methods was also 9.5 times lower in comparison to LBW-W and up to 14 times lower than in the case of arc welding methods;
the shielding gas consumption was 33.3 times lower compared to LBW-W and up to 32 times lower in comparison to the arc methods.
The laser welding methods (LW and HLAW) are technologically and economically optimal for application in the industry, especially in the case of large-sized structures made of St3 steel. Their implementation allows for increased accuracy, reduced costs and improved performance of the welded joints.
AUTHORS
Kuznetsov Mikhail Valerievich, Ph.D. in technical sciences, Head of the Research Laboratory “Laser and Additive Technologies”, Director of the Russian-German Center for Laser Technologies, Institute of Mechanical Engineering, Materials and Transport, Federal Autonomous Educational Institution of Higher Education “Peter the Great St. Petersburg Polytechnic University”, Saint-Petersburg, Russia. Area of expertise: hybrid laser-arc welding, laser welding, additive technologies, laser cladding, direct laser deposition. E-mail: kuznetsov_mich@mail.ru
ORCID: 0000-0002-9981-1078
Larin Maksim Vasilievich, engineer of the research laboratory “Laser and Additive Technologies”, junior researcher of the Russian-German Center for Laser Technologies, Institute of Mechanical Engineering, Materials and Transport, Federal Autonomous Educational Institution of Higher Education “Peter the Great St. Petersburg Polytechnic University”, Saint-Petersburg, Russia. Area of expertise: hybrid laser-arc welding, laser welding, additive technologies, laser cladding, direct laser deposition.
ORCID: 0000-0002-6382-7561
Kuznetsova Daria Aleksandrovna, engineer of the research laboratory “Laser and Additive Technologies”, junior researcher of the Russian-German Center for Laser Technologies, Institute of Mechanical Engineering, Materials and Transport, Federal Autonomous Educational Institution of Higher Education “Peter the Great St. Petersburg Polytechnic University”, Saint-Petersburg, Russia. Area of expertise: study of the structure and properties of casting alloys, technologies for obtaining and modifying nanomaterials and coatings, microstructural analysis.
ORCID: 0009-0003-3938-5710
Popovich Anatoly Anatolyevich, Doctor of Technical Sciences, professor, director of the Institute of Mechanical Engineering, Materials and Transport, Federal Autonomous Educational Institution of Higher Education “Peter the Great St. Petersburg Polytechnic University”, Saint-Petersburg, Russia. Area of expertise: development of theoretical fundamentals and efficient technologies for obtaining powders of refractory compounds and related alloys in the conditions of high-temperature mechanochemical synthesis, development of new anode and cathode materials for lithium-ion polymer batteries, additive technologies.
ORCID: 0000-0002-5974-6654
CONFLICT OF INTEREST
The authors declare no conflict of interest. All authors contributed to the paper in accordance with the task distribution. The authors agree with the text.
M. V. Kuznetsov, M. V. Larin, D. A. Kuznetsova, A. A. Popovich
Peter the Great St. Petersburg Polytechnic University, Saint-Petersburg, Russia
This paper presents the comparison results of laser and arc welding methods. The modes for laser welding, hybrid laser-arc welding and laser welding with filler wire for the St3 plates with the thickness of 10 mm were developed. Three test joints were welded by each welding method using the developed modes. The metallographic studies were conducted demonstrating stable formation of the welded joint and absence of internal defects. The residual deformations were assessed for the following types of welding: laser welding, hybrid laser-arc welding, laser welding with filler wire, single-sided and double-sided manual arc welding, single-sided and double-sided mechanized welding in the active gases and mixtures. The test samples for each welding type were analyzed in terms of the level of residual deformations after welding by comparing geometric dimensions and using the 3D scanning procedure. A comparative technical and economic analysis of welding methods was performed.
Keywords: laser-beam welding, hybrid laser-arc welding, laser welding with filler wire, residual deformations, 3D scanning
Article received: April 07, 2025
Article accepted: April 28, 2025
INTRODUCTION
In the Russian Federation, the issue of innovative domestic industrial development is extremely relevant. The welding and related technologies play an important role in the creation of innovative products: up to 50% of the gross output in heavy engineering is obtained using the welding and related technologies, and up to 67% of rolled metal products are used to produce the welded structures [1].
As a rule, the welded metal structures are manufactured using the manual arc welding (MMA), mechanized semiautomatic welding in gases and mixtures (MSW) or submerged arc welding methods. When preparing the parts to be welded, it is necessary to prepare the fusion edges, including chamfering, usually with a chamfer angle of up to 60 degrees. Then, welding is performed with the weld deseaming after each pass. For example, when welding the samples with the thickness of 60 mm using the MMA method, up to 74 passes can be made [2]. This is a rather labor-intensive process, leading to the decreased performance of the final product manufacturing process, an increased amount of consumed power, welding materials and an enhanced likelihood of internal defects.
Another issue during the welded joint formation is welding deformations. First of all, any deformations that occur as a result of welding complicate the assembly process for the large-sized structures consisting of individual welded blocks, units and sections, worsen the appearance, operational performance of the structure and require the introduction of additional operations to eliminate welding deformations, such as subsequent heat treatment, preliminary bending, expansion joints, elimination of the previously introduced allowance of up to several tens of millimeters for joining the components, etc.
Due to the peculiarities of arc welding processes, their use in the up-to-date production processes often does not meet the requirements, primarily in terms of performance and energy efficiency.
The most promising welding methods that meet the above requirements include laser welding (LW) [3, 4], hybrid laser-arc welding (HLAW) [5–7] and laser welding with filler wire (LBW-W) [8, 9] that have a number of advantages over the conventional methods, including local impact, minimal energy input, minimal width of the heat-affected zone (HAZ) and deformations.
Within the framework of this paper, the task was set to conduct a comprehensive study of the influence of various welding methods on the level of residual deformations, energy contribution and width of the heat-affected zone (HAZ) of the obtained welded joints, as well as on the economic efficiency of each method application.
1. Experimental and research equipment
1.1. Experimental Equipment
The development of the LW, HLAW and LBW-W modes, as well as welding of the test samples, was performed using a robotic process system for hybrid laser-arc welding (RPS HLAW) in the research laboratory “Laser and Additive Technologies” of the Institute of Mechanical Engineering of Materials and Transport in Peter the Great St. Petersburg Polytechnic University (Fig. 1). Welding of the samples by the MMA and MSW methods was performed by the employees of ECM LLC (Engineering. Construction. Maintenance).
For safety purposes, the RPS HLAW is made in a protective cabin, preventing the dangerous effect of reflected laser radiation. The cabin is equipped with the windows with light filters, CCTV cameras and ventilation. The composition of the RPS HLAW is given in Table 1. The laser source parameters are given in Table 2. The beam caustic is shown in Fig. 2.
1.2. Research Equipment
The formation quality of welded joints was studied using the transverse macrosections made by a PRESI MECATECH 234 automatic grinding and polishing machine. The metallographic studies of the samples were performed using an inverted optical microscope IM7400L (Meiji Techno, Japan). The 3D scanning procedure for the samples before and after welding was performed using a 3D scanner ScanTech TrackScan P42.
2. Welding materials
The samples (plates) with the dimensions of 300 × 100 × 10 mm, made of steel grade St3 were used in the work. The samples were prepared for each welding method: for MMA and MSW according to GOST 5264-80-C25 (Fig. 3). For MMA, an E50A electrode was used according to GOST 9467-75, for MSW, an OK AristoRod 12/63 ∅1.2 mm welding wire was used.
The cuts for the LW, HLAW and LBW-W methods are shown in Fig. 3. To measure the residual deformations, three holes with a diameter of 3 mm were made in the plates. The plate drawing is shown in Fig. 5.
The fusion edges of the plates and an area with the width of 1 cm from the edges were pre-cleaned using an angle grinder to a metallic shine and degreased with acetone. Prior to welding, the plates were placed in a rigid fixture and fixed (Fig. 6).
In the case of HLAW and LBW-W, the POWER PIPE 60R welding wire with a diameter of 1.2 mm was used. The chemical composition of the wire is given in Table 3.
To provide local protection of the welding pool, a mixture of Ar/СО2 gases was applied in the ratio of 80%/20%.
3. Experiment
When developing the LW, HLAW and LBW-W technologies, the single full-penetration welds were made in various modes. The criteria for determining the optimal welding mode were as follows: through penetration, stable and high-quality bead formation on the front and back sides, and absence of any defects. When developing the modes, the main process parameters were varied: laser radiation power (PL) in the range from 2000 W to 10000 W; welding speed (V) from 20 mm/sec to 30 mm/sec; changes in the distance from the laser head to the welded surface (dF) from –4 mm to +1 mm; wire feed speed (Vwf) from 0.6 m/min to 1.2 m/min; shielding gas consumption (R) from 25 l/min to 50 l/min. In the selected mode, three test joints were welded by each method in order to study any residual deformations. Prior to welding, the plates were tacked from the back side of the joint in the welding mode.
Before the tack welds and after welding, for subsequent analysis of deformations, the distances S1, S2, S3, S4, S5 were measured according to the diagram shown in Fig. 7.
4. Welding of samples
4.1. Welding of Samples by Arc Methods
The test samples manufactured by the MMA and MSW methods were formed respectively by welding from one side (MMA1 and MSW1) in 3 passes and welding from two sides (MMA2 and MSW2) in 4 passes. The end views of the welded samples are shown in Fig.8.
4.2. Welding of Samples by Laser Methods
The parameters of modes in which the test samples were welded using the LW, HLAW and LBW-W methods are given in Table 4. Fig. 9 shows the end view of the welded samples.
5. Metallographic studies
During the metallographic studies, the transverse macrosections of sampled welded joints for each welding method were prepared (Fig. 10). The photographs of such macrostructures show no internal defects (except for MSW1), such as any pores, cracks and lack of penetration. A defect in the form of lack of penetration with the length of about 2 mm and width of up to 0.5 mm was found in the transverse macrosection of MSW1. According to the requirements of the ultrasonic inspection (STO 00220256–005–2005) imposed during the weld inspection, this defect is acceptable.
Based on the macrosection analysis results, it was noted that in the case of LW and HLAW, the HAZ width was 7–8 times smaller compared to the HAZ width of the welds obtained by the MSW and MMA methods and amounted to 0.32 mm and 0.4 mm, respectively.
As a result of the microstructural control of the studied samples (LW; HLAW; LBW-W; MMA1; MMA2; MSW1; MSW2), the defects in the form of numerous pores were found. These defects may be related to the steel production technology, or to the availability of non-metallic inclusions, as well as gas porosity occurred during the recrystallization process.
Fig. 11 shows the base metal microstructure of the samples under study. It is evident that the metal structure is uniform and even, without any signs of banding. The structure is a ferrite and pearlite mixture, with a ferrite to pearlite ratio of 35/65% according to scale 7 in GOST 8233-56.
The grain size analysis shows that the value for all samples corresponds to 7–8 points, and near the weld seam – 8–9 points according to scale 1 in GOST 5639-82. Fig. 12 shows the microstructure of welds for each welding method.
The microstructural analysis of the welded joint, including the weld zone, fusion zone and heat-affected zone, is given in Table 5.
6. Analysis of residual deformations and feasibility study of welding methods
6.1. Results of Residual Deformation Analysis Using the Hole Spacing Method
The residual deformations for laser welding methods were assessed by comparing the sizes S1, S2, S3, S4, S5 (Fig. 10) obtained before and after welding. The measurements were performed using ШЦ‑1 from the front side of the seam for all three test joints obtained by the LW, HLAW, LBW-W methods, after which the arithmetic mean value was determined for each size.
Table 6 shows the measurement results and also indicates the difference between these values. According to the data (Table 6), the smallest residual deformations were observed in the case of HLAW and LW: in the longitudinal section – 0.21 mm and 0.26 mm, respectively; in the transverse section, the deformations were not registered.
The maximum values of deformations were observed for LBW-W: in the longitudinal direction – 0.79 mm; in the transverse direction – 0.25 mm. The comparable deformations in the case of MSW2: 0.81 mm and 0.32 mm, respectively. In order to verify the measurement results, the residual deformation measurements were additionally performed using the 3D scanning method.
6.2. Analysis of Residual Deformations by the 3D Scanning Method
To confirm the analysis results for the welded joint deformations (Table 5) generated using the laser welding methods at the Research Laboratory “Laser and Additive Technologies” of the Institute of Mechanical Engineering, Materials and Transport, Peter the Great St. Petersburg Polytechnic University, all test samples were scanned after welding by a 3D scanner TrackScan P42. In the GeoMagic Control X program the scanned models of samples were compared with a reference sample without any deformations, after which a deviation map was prepared (Fig. 12).
The results of deviation measurements at 6 points by the module are given in Table 7. The measurement scheme at 6 points is shown in Fig. 14.
Based on the calculation results, the maximum deviations were registered for LBW-W and amounted to 0.87 mm. The minimum deviations were registered for HLAW (0.3 mm) and LW (0.38 mm) that can be justified by the minimum rate of energy input and the HAZ width.
6.3. Feasibility Study of Welding Methods
A comparative efficiency analysis of the welding methods was performed using the transverse macrosections of welded joints.
The analysis results showed that the rate of energy input for LW and HLAW was 6.5 times lower than this indicator for LBW-W and up to 15 times lower than for MMA and MSW. The welding wire consumption when comparing the similar welding methods was also 9.5 times lower than for LBW-W and up to 14 times lower than for the arc welding methods. The shielding gas consumption was 33.3 times lower than for LBW-W and up to 32 times lower than for the arc welding methods. Fig. 15 shows a diagram comparing welding methods as a percentage (%) of the maximum indicator value.
CONCLUSION
Based on the comprehensive study results related to the influence of various welding methods on the level of residual deformations, energy contribution and width of the heat-affected zone (HAZ) of the obtained welded joints, as well as on economic efficiency, the following was established:
the minimum welding deformations were registered in the case of ALHW (0.21–0.3 mm), as well as LW, where the deformations were 4 times lower than in the case of LBW-W;
the smallest HAZ width was registered for LW and HLAW (0.32 mm and 0.4 mm, respectively) that was up to 8 times less than for MMA and MSW;
the rate of energy input for LW and HLAW was 6.5 times lower compared to the LBW-W and up to 15 times lower compared to MMA and MSW;
the welding wire consumption when comparing the similar welding methods was also 9.5 times lower in comparison to LBW-W and up to 14 times lower than in the case of arc welding methods;
the shielding gas consumption was 33.3 times lower compared to LBW-W and up to 32 times lower in comparison to the arc methods.
The laser welding methods (LW and HLAW) are technologically and economically optimal for application in the industry, especially in the case of large-sized structures made of St3 steel. Their implementation allows for increased accuracy, reduced costs and improved performance of the welded joints.
AUTHORS
Kuznetsov Mikhail Valerievich, Ph.D. in technical sciences, Head of the Research Laboratory “Laser and Additive Technologies”, Director of the Russian-German Center for Laser Technologies, Institute of Mechanical Engineering, Materials and Transport, Federal Autonomous Educational Institution of Higher Education “Peter the Great St. Petersburg Polytechnic University”, Saint-Petersburg, Russia. Area of expertise: hybrid laser-arc welding, laser welding, additive technologies, laser cladding, direct laser deposition. E-mail: kuznetsov_mich@mail.ru
ORCID: 0000-0002-9981-1078
Larin Maksim Vasilievich, engineer of the research laboratory “Laser and Additive Technologies”, junior researcher of the Russian-German Center for Laser Technologies, Institute of Mechanical Engineering, Materials and Transport, Federal Autonomous Educational Institution of Higher Education “Peter the Great St. Petersburg Polytechnic University”, Saint-Petersburg, Russia. Area of expertise: hybrid laser-arc welding, laser welding, additive technologies, laser cladding, direct laser deposition.
ORCID: 0000-0002-6382-7561
Kuznetsova Daria Aleksandrovna, engineer of the research laboratory “Laser and Additive Technologies”, junior researcher of the Russian-German Center for Laser Technologies, Institute of Mechanical Engineering, Materials and Transport, Federal Autonomous Educational Institution of Higher Education “Peter the Great St. Petersburg Polytechnic University”, Saint-Petersburg, Russia. Area of expertise: study of the structure and properties of casting alloys, technologies for obtaining and modifying nanomaterials and coatings, microstructural analysis.
ORCID: 0009-0003-3938-5710
Popovich Anatoly Anatolyevich, Doctor of Technical Sciences, professor, director of the Institute of Mechanical Engineering, Materials and Transport, Federal Autonomous Educational Institution of Higher Education “Peter the Great St. Petersburg Polytechnic University”, Saint-Petersburg, Russia. Area of expertise: development of theoretical fundamentals and efficient technologies for obtaining powders of refractory compounds and related alloys in the conditions of high-temperature mechanochemical synthesis, development of new anode and cathode materials for lithium-ion polymer batteries, additive technologies.
ORCID: 0000-0002-5974-6654
CONFLICT OF INTEREST
The authors declare no conflict of interest. All authors contributed to the paper in accordance with the task distribution. The authors agree with the text.
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