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• The 2045 W laser is used for laser cladding. • This Gaussian light into a rectangular beam conversion facilitates high speed and efficient cladding. • The ball valve is crack-free and its surface hardness has been increased by 2.7 times. In this paper, the laser cladding of Ni60 + WC powder on the stainless-steel ball valves is investigated to improve the corrosion resistance and the wear resistance of industrial ball valves. A 2-kW high-power diode laser source based on beam multiplexing is used as the processing source to clad the ball valves. To make this diode laser source more reliable for laser cladding, a homogenizing optical system is designed and optimized to transform a circular beam spot output from the optical fiber to a rectangular spot with a flat-top distribution. Employing this diode laser source, the laser cladding of the stainless-steel ball valve is successfully achieved by use of the pre-set powder feeding. The hardness testing experiments are then performed on the ball valves of different diameters, followed by the evaluation of the thickness and hardness of the cladding coating. It is experimentally demonstrated that the microhardness of the ball valves is improved by 2.7 times and the cladding layer has no cracks, which proves the superior performance of the stainless-steel ball valves by use of the proposed method. [ABSTRACT FROM AUTHOR]

Highlights • A diode laser with an output power of 2 kW based on the multi-wavelength multiplexing is introduced. • A theoretical laser cutting model is built to predict the cutting performance of a direct diode laser source. • The cutting result of the diode laser is better than that of the fiber laser when the thickness of sheet is more than 3 mm. Abstract In this paper, a theoretical laser cutting model based on absorption calculations and the characteristics of multi-wavelength laser beam is introduced to predict the cutting performance of a direct diode laser source (2 kW output power from an optical fiber with a 105 μm core diameter and a numerical aperture of 0.2). Cutting experiments are performed on stainless steel sheets (304) with thicknesses ranging from 1 mm to 10 mm. When comparing with the relevant industrial cutting results using fiber lasers, this diode laser source can obtain a greater speed at the thickness of samples above 3 mm. The experimental results have a good agreement with the theoretically predicted results and demonstrate the cutting ability of the diode laser source of such power class and brightness class for use in industrial laser cutting applications. [ABSTRACT FROM AUTHOR]

• A 3-spot processing method is introduced for cladding stainless-steel ball valves. • Cladding of stainless-steel ball valves are completed with Ni60 + WC powder. • Cladded samples are free from any defects such as cracks and pores. In this paper, aiming to solve the problem of cracks in the laser cladding for stainless-steel ball valves, a novel method for defect-free processing is introduced. To realize this method, a 3-spot high-power diode laser source is developed. These three spots are respectively used for dynamic local preheating, laser cladding processing and dynamic local tempering. Using this high-power diode laser, a cladding processing of the stainless-steel ball valve with Ni60 + WC powder is successfully completed. Compared with the traditional processing approach, the cladded sample is free from any defects such as cracks and pores, which demonstrates the processing effect of this approach. This work provides a new method for the laser cladding of stainless-steel ball valves. [ABSTRACT FROM AUTHOR]

• A novel welding model is introduced for the butt welding of tailor-welded blanks. • Inspection results prove that this method can satisfy the industrial requirement. • It can simplify processing procedures and improve production efficiency. Due to weld defects occurred in the traditional laser welding of tailor-welded blanks with different thicknesses, a novel processing method is proposed in this paper. In this method, thin and thick metal plates are obliquely cut and then butt jointed to form an eave-like structure. When a laser beam irradiates on the marginal area of the thick plate, the molten metal flows into the gap and welds two plates together. Using this method, stainless steel tailor-welded blanks with a plate thickness combination of 2.0 mm and 1.0 mm are successfully welded by a diode laser source, and welded samples are free from cracks and pores. This method supplies a concise and quick processing way for the processing of tailor-welded blanks in industry. [ABSTRACT FROM AUTHOR]

We report on the development of direct diode laser source with high-power and high reliability. The laser source was realized by the polarization and wavelength combination of four diode laser stacks. When at the operating current of 122 A, the source was capable of producing 10,120 W output while maintaining 46% electro-optical conversion efficiency. The maximum temperature on the lens was decreased from 442.2 K to 320 K by utilizing an efficient thermal dissipation structure, and the corresponding maximum von Mises stress was reduced from 75.4 MPa to 14 MPa. In addition, a reliability test demonstrated that our laser source was reliable and potential in the applications of laser cladding and heat treatment. [ABSTRACT FROM AUTHOR]

• The beam from diode laser is converted to a flat-top distribution for laser hardening. • A detailed investigation on HOSs with different parameters are simulated by using ZEMAX. • A Rockwell hardness of 57 HRC and a hardened depth of 1.6 mm are obtained on 35CrMo metal steel. In this paper, a laser beam from a fiber coupled diode laser source is converted from a Gaussian-like distribution to a flat-top distribution using a set of homogenization optical system, which makes this diode laser source more favorable for laser hardening. Employing this diode laser source, hardening experiments are performed on 35CrMo metal steel. By optimizing parameters of the hardening processing, at the scanning speed of 1100 mm/min and laser power of 1940 W, a Rockwell hardness of 57 HRC and a hardened depth of 1.6 mm are achieved. Experimental results demonstrate the processing ability of this diode laser source in the industrial laser hardening. [ABSTRACT FROM AUTHOR]