US 12,109,649 B2
Laser welding method for enhanced weld quality and enhanced surface smoothness
Brahma Nand Upadhyaya, Indore (IN); Pushkar Misra, Indore (IN); Suresh Chandra Vishwakarma, Indore (IN); Rajesh Arya, Indore (IN); Srikant M. Oak, Indore (IN); and Purushottam Das Gupta, Indore (IN)
Assigned to SECRETARY, DEPARTMENT OF ATOMIC ENERGY, Mumbai (IN)
Appl. No. 16/999,814
Filed by SECRETARY, DEPARTMENT OF ATOMIC ENERGY, Mumbai (IN)
PCT Filed Feb. 24, 2018, PCT No. PCT/IB2018/051168
§ 371(c)(1), (2) Date Aug. 21, 2020,
PCT Pub. No. WO2019/162726, PCT Pub. Date Aug. 29, 2019.
Prior Publication US 2021/0354240 A1, Nov. 18, 2021
Int. Cl. B23K 26/21 (2014.01); B23K 26/32 (2014.01); B23K 103/14 (2006.01)
CPC B23K 26/21 (2015.10) [B23K 26/32 (2013.01); B23K 2103/14 (2018.08)] 9 Claims
OG exemplary drawing
 
1. A laser welding method for enhanced weld quality and enhanced surface smoothness, said method comprising steps of:
a. delivering a high energy and long pulse solid state Nd: YAG laser beam in a first pass on a material to be welded;
b. delivering a Nd: YAG laser beam in a second pass with a welding nozzle inclined at an angle from normal of a weld bead and a power density of the laser beam in the second pass is lower than a power density of the laser beam in the first pass;
such that a peak power density of the first pass is below a peak power density required for evaporation of a surface of the material to be welded without forming a keyhole; and
such that an inclination of the second pass lies in a plane, which does not contain the weld bead and a direction of motion of the second pass is opposite to a direction of motion of the first pass for full depth penetration;
wherein delivery of the laser beam in the second pass is carried out with the welding nozzle inclined at an angle 20°-45° from normal of the weld bead, and
wherein the beam of the first pass has a long pulse duration of 1 ms-100 ms.