Butt-joint deep penetration laser welding method

Abstract

A butt joint deep penetration laser welding method is used for joining facing end sections of flat steel products, each having a carbon content CS<0.02%. In order to improve such a method such that an improved weld quality in terms of geometry and strength is achievable with it, at least one carbon-containing carrier material is inserted into a butt joint gap between the end sections, the carbon content of which is C.sub.T≥20.Math.C.sub.S, preferably C.sub.T≥100.Math.C.sub.S, and/or carbon is inserted into the butt joint gap or applied to at least one end section, such that the volume of the carbon inserted into the butt joint gap corresponds to 1% to 20% of the volume of a melt produced by a butt joint deep penetration laser welding process.

Claims

1.-11. (canceled)

12. A butt joint deep penetration laser welding method for joining facing end sections of flat steel products, each having a carbon content C.sub.S<0.02%, comprising at least one of: inserting a carbon-containing carrier material into a butt joint gap between the end sections or applying a carbon-containing carrier material to at least one end section, a carbon content of the carrier material being C.sub.T≥20.Math.C.sub.S with C.sub.S being the carbon content of the flat steel product having a larger carbon content, and inserting carbon into the butt joint gap or applying carbon to at least one of the end sections, such that a volume of the carbon inserted into the butt joint gap corresponds to 1% to 20% of a volume of a melt produced while joining the end sections during deep penetration laser welding.

13. The method as in claim 12, wherein the carbon content of the carrier material is C.sub.T≥100.Math.C.sub.S.

14. The butt joint deep penetration laser welding method according to claim 12, wherein a solid-state laser is used as a laser beam source.

15. The butt joint deep penetration laser welding method according to claim 14, wherein a fiber laser or a disk laser or a diode laser is used as the laser beam source.

16. The butt joint deep penetration laser welding method according to claim 14, wherein the solid-state laser has a wavelength in a range of 980 nm to 1120 nm.

17. The butt joint deep penetration laser welding method according to claim 14, wherein the solid-state laser operates at a welding speed in a range of 1 m/min to 10 m/min.

18. The butt joint deep penetration laser welding method according to claim 12, wherein the carrier material is a metallic powder.

19. The butt joint deep penetration laser welding method according to claim 12, wherein the carrier material is a graphite-containing metallic foil.

20. The butt joint deep penetration laser welding method according to claim 12, wherein the carrier material is a graphite-containing fluid.

21. The butt joint deep penetration laser welding method according to claim 20, further comprising actively drying the fluid after its insertion into the butt joint gap.

22. The butt joint deep penetration laser welding method according to claim 12, wherein the carrier material is a fluxed cored wire or a sheet.

23. The butt joint deep penetration laser welding method according to claim 12, wherein the carrier material is applied to an abutting surface of at least one of the end sections prior to applying laser radiation, after which the butt joint gap is closed.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] FIG. 1 is a block diagram of an exemplary embodiment of a butt joint deep penetration laser welding method.

DETAILED DESCRIPTION

[0032] FIG. 1 shows a block diagram of an exemplary embodiment of a butt joint deep penetration laser welding method for joining facing end sections of flat steel products, each having a carbon content C.sub.S<0.02%.

[0033] In method step 10, a carbon-containing carrier material is inserted into a butt joint gap between facing end section of flat steel products or applied to at least one end section. A carbon content of the carrier material is C.sub.T≥20.Math.C.sub.S, preferably C.sub.T≥100.Math.C.sub.S, wherein C.sub.S is the carbon content of at least that flat steel product having the higher carbon content. In addition or alternatively, in method step 10, carbon is inserted into the butt joint gap or applied to at least one end section such that the volume of the carbon inserted into the butt joint gap corresponds to 1% to 20% of a volume of a melt produced by a butt joint deep penetration laser welding method.

[0034] The carrier material or the carbon, in particular pure carbon, is applied to an abutting surface of at least one end section in method step 16, prior to the use of the laser radiation in method step 20, after which the butt joint gap is closed. A metallic powder can be used as the carrier material. Alternatively, a graphite-containing metallic foil can be used as the carrier material. Alternatively, a fluid containing graphite can be used as the carrier material, which can be actively dried after its insertion into the butt joint gap. Alternatively, a flux-cored wire or a sheet can be used as the carrier material.

[0035] In method step 20, laser radiation is generated and directed to the butt joint gap into which the carbon-containing carrier material or carbon has been inserted, such that a butt joint deep penetration laser welding process can be carried out. In doing so, a solid-state laser is used as the laser beam source. In particular, a fiber laser or a disk laser or a diode laser can be used as the laser beam source. Laser radiation is generated and used with a wavelength in a range of 980 nm to 1120 nm. The laser deep penetration welding process carried out in method step 20 is carried out at a welding speed in a range of 1 m/min to 10 m/min.

LIST OF REFERENCE SIGNS

[0036] 10 Method step (insertion of carrier material)

[0037] 20 Method step (laser deep penetration welding process)