1：Experimental Design and Method Selection:

Central composite design (CCD) module was selected to develop the experiment design in Design Expert software (version

2：0). Laser power (LP), scanning speed (SS), and gas flow (GF) were the selected as the processing parameters to be altered in this study. The AISI/SAE 1045 steel tubes with different outside diameters was another factor to be investigated to provide an industrial application reference. Sample Selection and Data Sources:

The substrates selected in this study, AISI/SAE 1045 steel tubes, were 70 mm in length and had a 5 mm wall thickness with different outside diameters. The cladding powder was high-speed steel powder (W6Mo5Cr4V2), which was produced by Chengdu Huayin Powder Technology CO., LTD (Chengdu, China).

3：List of Experimental Equipment and Materials:

The laser cladding system used in this study consisted of a continuous wave laser system with 1064 nm wavelength (YLS-3000, IPG, Burbach, Germany), laser cladding nozzle with 300 mm focal length and

4：6 mm focal spot diameter (FDH0273, Lasermech, Novi, MI, USA), industrial robot (M-710iC/50, FANUC, Yamanashi, Japan), water cooling system (TFLW-4000WDR-01-3385, Sanhe Tongfei, Sanhe, China), powder feeding system (CR-PGF-D-2, Songxing, Fuzhou, China), a three-jaw universal chuck operated by a computer control system (PLC, Mitsubishi, Japan), and a laser pulse control system (SX14-012PULSE, IPG, Burbach, Germany). Argon gas was used as carrier and protective gas during the cladding process. Experimental Procedures and Operational Workflow:

Before conducting the cladding process, the substrate surface was cleaned with absolute ethanol. The high-speed steel powder was dried in a vacuum dryer at 120 °C for 30 min to prevent clogging in the powder feeding system. Thirty experimental runs were conducted following the setup in Table

5：Data Analysis Methods:

Response surface methodology (RSM) was used to establish mathematical models between the input variables and responses. Analysis of variance (ANOVA) was used to verify and analyze the fitted models. The significance level (α) was set at 0.05.