**4. Technology of HLAW**

There are several fields of applications [31], in which usage of HLAW is especially prospective. First of them is production of large diameter pipes for oil and gas. The technology for different thickness of pipe walls was designed and the examples are shown in **Figure 20**.

**Figure 20.** Macrosection of the one pass weld (left), three passes weld (center – first technological pass), right – techno‐ logical pass and two filled passes by submerged arc welding. Depth is 15 mm left and 24 mm center and right. Materi‐ al is steel X80.

**Figure 22.** Butt HLAW joint in shipbuilding section (Material – steel PCE36, 20 mm thickness) – left, angle joint in ship‐

Laser and Hybrid Laser-Arc Welding http://dx.doi.org/10.5772/64522 147

building section (Material – steel 09Г2C 15 mm thickness) – right.

**Figure 23.** Comparison of MAG welded ship body section (left) with HLAW case (right).

**5. Peculiarity of metal structure formation in hybrid welding**

However, it is necessary to ensure satisfactory plastic weld characteristics.

powerful lamp.

To reduce the constructions weight new high-strength steels are applied. Characteristics of these steels are determined by parameters of ensembles of ultrafine inclusions. New technol‐ ogies for car bodies are based on tailored blanks. Weight reduction without decreasing the strength is achieved by using high-strength steels and alloys in the production blanks.

This requires the use of welding technique, which provides the required level of ductility of weld seams and the same quality as laser welding process provides. Using a high-speed thermal cycling is the one of most promising techniques for getting good microstructure and mechanical properties [33]. This may be accomplished by welding two heat sources following one after another, for example, tandem laser welding [34]. However, from an economic standpoint it is advisable to use cheap local sources of heating as the second source, such as a

To select treatment regimes, which provide the requisite microstructure and properties of the alloy, it is necessary to have a quantitative definition of the effect of temperature cycling on phase and structural transformations in the material. Modern concepts of phase transforma‐

Optimization of arc torch position relative to laser beam and optimization of composition of arc gas mixture together with usage of specially designed filler wire with ultrafine admixtures allow to avoid appearance of different defects, such as porosity, hot cracks, and humping. Also, it provides value of impact energy on temperature −40°C in the bounds of 140–200 J for pipe steel X80. HLAW also could be used for welding of nonturnable joints during pipeline building. In this case, hybrid scheme allows to increase not only the process productivity and joint quality but also process tolerance. Technology allows appropriate weld formation even in the case of more than 3 mm of vertical displacement of pipe joint edges (**Figure 21**).

**Figure 21.** Root pass side. Orbital pipeline hybrid welding with 2 mm gap and 3 mm vertical displacement.

Next prospective field of HLAW is shipbuilding [32]. Usage of this technology allows to increase dramatically the productivity of creation of flat sections for ship body. Because HLAW allows to get a weld with parallel walls displacement (**Figure 22**), it is possible to minimize welding stress and distortions, as shown in **Figure 23**.

**Figure 22.** Butt HLAW joint in shipbuilding section (Material – steel PCE36, 20 mm thickness) – left, angle joint in ship‐ building section (Material – steel 09Г2C 15 mm thickness) – right.

**Figure 23.** Comparison of MAG welded ship body section (left) with HLAW case (right).

**Figure 20.** Macrosection of the one pass weld (left), three passes weld (center – first technological pass), right – techno‐ logical pass and two filled passes by submerged arc welding. Depth is 15 mm left and 24 mm center and right. Materi‐

Optimization of arc torch position relative to laser beam and optimization of composition of arc gas mixture together with usage of specially designed filler wire with ultrafine admixtures allow to avoid appearance of different defects, such as porosity, hot cracks, and humping. Also, it provides value of impact energy on temperature −40°C in the bounds of 140–200 J for pipe steel X80. HLAW also could be used for welding of nonturnable joints during pipeline building. In this case, hybrid scheme allows to increase not only the process productivity and joint quality but also process tolerance. Technology allows appropriate weld formation even in the case of more than 3 mm of vertical displacement of pipe joint edges (**Figure 21**).

**Figure 21.** Root pass side. Orbital pipeline hybrid welding with 2 mm gap and 3 mm vertical displacement.

welding stress and distortions, as shown in **Figure 23**.

Next prospective field of HLAW is shipbuilding [32]. Usage of this technology allows to increase dramatically the productivity of creation of flat sections for ship body. Because HLAW allows to get a weld with parallel walls displacement (**Figure 22**), it is possible to minimize

al is steel X80.

146 Joining Technologies
