Method of welding in deep joints

1. A method of welding for joining two metallic components, the method comprising:

arranging a first metallic component of the two metallic components and a second metallic component of the two metallic components for a zero gap portion and a non-zero gap portion therebetween;

joining the two metallic components at the zero gap portion with a root weld;

joining the two metallic components at the non-zero gap portion with a fill up weld;

melting the two metallic components in a weld region of the root weld and the fill up weld into a molten state to form a weld pool through an energy input by directing at least one first source of energy on the two metallic components to join the two metallic components; and

focusing at least one second source of energy to heat a heating region, which heating region surrounds the weld pool from all sides, to reduce cooling rate and extend solidification time of the weld pool,

wherein the at least one second source of energy is adapted to be focused in multiple positions of the heating region via multiple heat sources, the multiple positions including:

at least one leading pre-heating position in front of the weld pool,

at least one trailing post-heating position behind the weld pool,

at least one first side position on the first metallic component, the at least one first side position adjacent the weld pool and between the at least one leading pre-heating position and the at least one trailing post-heating position, and

at least one second side position on the second metallic component, the at least one second side position adjacent the weld pool and between the at least one leading pre-heating position and the at least one trailing post-heating position.

2. The method as claimed in claim 1 , wherein the two metallic components are joined in two stages, the first stage being the root weld made without use of filler wire and the second stage being the fill-up weld made with use of filler wire.

3. The method as claimed in claim 1 , wherein the two metallic components are high- or low-alloy heat-resistant steel and Nickel-based material.

4. The method as claimed in claim 1 , wherein the at least one first source of energy is a single heat source or multiple heat sources.

5. The method as claimed in claim 4 , wherein the at least one first source of energy and the at least one second source of energy are beams of energy sources from electric arc sources, laser sources, electron beam sources, plasma sources, ultrasonic beams or a combination thereof.

6. The method as claimed in claim 5 , wherein the at least one first source of energy is an arc based tungsten inert gas torch.

7. The method as claimed in claim 5 , wherein the at least one second source of energy is a moving beam.

8. The method as claimed in claim 7 , wherein the at least one second source of energy is an oscillating laser beam.

9. The method as claimed in claim 7 , wherein the at least one second source of energy is a weaving laser beam.

10. The method as claimed in claim 7 , wherein the moving beam is via multiple heat sources located at multiple locations above the weld pool.

11. The method as claimed in claim 1 , wherein heating at the at least one first side position and at the at least one second side position induces a compressive stress to pull and keep both the first metallic component and the second metallic component with zero gap thereby reducing a tolerance limit for zero gap in the root weld.

12. The method as claimed in claim 7 , wherein the moving beam is power modulated.

13. The method as claimed in claim 7 , wherein the moving beam is a focused low power laser beam or a defocused high power laser beam to heat the heating region surrounding the weld pool from all sides in a narrow gap geometry for all joint depths.

14. The method as claimed in claim 12 , wherein more power is applied for heating a first region of heating positions, and less power is applied for heating a second region of the heating positions.

15. The method as claimed in claim 1 , wherein the two metallic components are in vertical position and the at least one first source of energy is in horizontal position during welding.

16. The method as claimed in claim 1 , wherein the two metallic components are in horizontal position and the at least one first source of energy is in vertical position during welding.

17. A method of welding for joining two metallic components, the method comprising:

directing at least one first source of energy on a first metallic component of the two metallic components and a second metallic component of the two metallic components;

melting the first metallic component and the second metallic component in a weld region of the first metallic component and the second metallic component into a molten state to form a weld pool through an energy input by the at least one first source of energy; and

focusing a plurality of second sources of energy to heat a heating region, the heating region surrounding the weld pool from all sides to reduce cooling rate and extend solidification time of the weld pool,

wherein the plurality of second sources of energy are adapted to be focused in multiple positions of the heating region via multiple heat sources, the multiple positions including:

at least one leading pre-heating position in front of the weld pool,

at least one trailing post-heating position behind the weld pool,

at least one first side position on the first metallic component, the at least one first side position adjacent the weld pool and between the at least one leading pre-heating position and the at least one trailing post-heating position, and

at least one second side position on the second metallic component, the at least one second side position adjacent the weld pool and between the at least one leading pre-heating position and the at least one trailing post-heating position.