1：Experimental Design and Method Selection:

The study compares laser cladding (LC), laser-induction hybrid cladding with pre-heating (pre-LIHC), and laser-induction hybrid cladding with post-heating (post-LIHC) for depositing Ni-based coatings on a full-scale U71Mn rail. The rationale is to investigate cracking behaviors, microstructures, and mechanical properties to overcome barriers in rail hardfacing and repair.

2：Sample Selection and Data Sources:

A full-scale U71Mn rail (

3：2 m length) is used as the substrate, with chemical composition provided. Ni-based alloy powder (20–50 μm particle size) is used for cladding. List of Experimental Equipment and Materials:

Equipment includes a 6 kW continuous wave fiber laser (YLR-6000, IPG), a 6-axis robot (KUKA), a powder feeder (HUST-Ш), an induction heating device, infrared thermometers, thermocouples, optical microscopy (NIKON EPIPHOT 300), scanning electron microscopy (SEM, Sirion 200), X-ray diffraction (XRD), electron probe microanalyzer (EPMA, SHIMADAZU EPMA-8050G), in-situ nano-indentation apparatus (Hysitron TI750), EBSD detector (Nordlys Max3, Oxford), Vickers hardness tester, and Shimadzu AG-100 kN tensile tester. Materials include U71Mn rail and Ni-based alloy powder.

4：Experimental Procedures and Operational Workflow:

Coatings are deposited using LC, pre-LIHC, and post-LIHC with specified parameters (laser power, scanning rate, powder feeding rate, spot size, induction temperature). Thermal cycles are monitored. Metallographic, EBSD, and tensile specimens are prepared from the claddings. Microstructures are characterized, and mechanical properties are tested.

5：Data Analysis Methods:

Software like image-pro plus 6.0 is used for measuring secondary dendrite arm spacing and interdendrite content. EBSD data is analyzed with Oxford Instruments Aztec software. Tensile properties and nano-indentation data are analyzed statistically.