In order to study the effect of laser power density on the microstructure and properties of laser remelting 304 stainless steel, the temperature field and phase transition model of pulsed laser remelting stainless steel were established, and the temperature distribution and phase transition zone boundary during laser remelting were analyzed. The effects of laser power density on the microstructure, element distribution, hardness and corrosion resistance of the remelting layer on the surface of stainless steel were studied. The simulation and experimental results show that with the increase of laser power density, the surface temperature of stainless-steel increases gradually, and the surface quality of remelted layer becomes better and then worse. After laser remelting of 304 stainless steel, the hardness of the remelting layer is higher than that of the substrate, the self-corrosion potential shifts to the right, the self-corrosion current density decreases, and the corrosion resistance increases. Laser remelting technology is beneficial to improve the comprehensive properties of 304 stainless steel surface.
The present study presents comprehensive analytical solutions for the thermoelastic response of semi-infinite media subjected to exponentially decaying volumetric heat sources with two distinct temporal profiles, namely exponential decay and rectangular step pulses. The governing coupled thermoelastic equations are nondimensionalized using characteristic thermal diffusion scales, revealing the fundamental parameter gamma = c(1) (2)/ alpha(2) delta(2) that governs the relative importance of elastic wave propagation to thermal diffusion. Closed-form solutions are derived for both temperature and stress fields using Laplace transform techniques, yielding expressions involving complementary error functions with complex arguments. The stress solutions are decomposed into five distinct wave propagation, and causal elastic response. A novel compact operator formulation is introduced for the step pulse solution, demonstrating the principle of superposition and revealing the self-similar nature of the thermoelastic problem. The solutions show that maximum thermal stresses do not necessarily coincide with maximum temperatures in space or time, particularly for rapid heating cases where elastic waves propagate ahead of the thermal front. The analytical results provide fundamental insights into the selection of optimal pulse parameters for applications ranging from laser material processing to thermal barrier coating evaluation, where control of thermal stress is critically important for preventing material damage.
To conduct an in-depth investigation into the impact of laser welding process parameters on the welding surface quality and welding deformation, qualitative laws summarising the influence of welding parameters, proposing optimal combinations of welding process parameters, multidimensional experimental analysis is used to analyse 304 stainless steel sheet. Firstly, the effects of the main laser welding parameters are initially determined by simulation, then a multidimensional experimental matrix was established, encompassing a variety of methodologies, such as single-factor, single-factor targeted, orthogonal, repeatability. In the experiments, the weld surface quality and weld distortion were assessed using a high magnification CCD camera and a six-jointed hand-held measuring arm, respectively. Through simulation and process experiments, the qualitative laws of welding speed, welding power and defocusing amount on welding surface quality and welding deformation are summarised, and the effect of welding power is further subdivided into the separate laws of peak welding power and duty cycle. The implications of this multidimensional experimental analysis are significant for intelligent upgrading and transformation of tasks within mechanical manufacturing enterprises. This meticulous experimental analyses and qualitative research contributes to the refinement and enhancement of previously vague empirical rules, thereby providing a clearer and more coherent understanding of qualitative patterns. This study is a foundational step towards facilitating the intelligent transformation of relevant enterprises and workshops.
Laser drilling can provide precise holes in hard-to-machine materials, yet its environmental assessment in terms of life cycle, is often confined to beam-on energy. This consideration of narrow metric, in general, omits significant contributors to processes such as cooling and vacuum loads, warm-up and idle power, assist-gas production, and rework that substantially influence overall sustainability of the manufacturing process. The current study develops a gate-to-gate life-cycle assessment (LCA) for laser drilling of AISI 304 steel and Inconel 625 alloy. A 500 W Nd:YAG laser drilling process was assessed using a foreground inventory that includes laser electricity, vacuum-pump electricity with measured duty factor, shielding-gas (argon) consumption, and upstream impacts of removed material. The relevant parameters considered and tested in the analysis were drilled hole size, electricity mix (fossil fuel-based vs renewable), and laser substitution (Nd:YAG laser vs CO2 laser). Findings demonstrates that for AISI 304 steel, operational energy dominates global warming potential (GWP), whereas for Inconel 625 alloy the material term becomes comparable or dominant across toxicity, resource scarcity, and land-use categories. Argon production is a major contributor to ionizing radiation and water consumption, indicating that gas management is a high-leverage opportunity for impact reduction. Increasing hole volume raises all impacts, the relative rise is larger for Inconel, notably for mineral resource scarcity and toxicity, reflecting Nickel, Molybdenum, and Tantalum intensive supply chains. At constant geometry, substituting a CO2 laser yields larger GWP reductions (36-38%) than a grid switch to renewable (13-14%), while the cleaner energy grid slightly increases ionizing-radiation and water use midpoints (CO2 substitution reduces water use by similar to 27%). The LCA therefore connects operational parameters (pulse and scan settings, gas flow, pump duty cycles, and equipment selection) and upstream procurement choices (electricity mix and assist-gas selection) to per-hole impacts, providing a documented foundation for co-optimizing quality, productivity, and environmental performance in industrial drilling of AISI 304 steel and Inconel 625 alloy.
In order to improve the surface properties of 45 steel, laser cladding technology was used to prepare CoCrNi composite coatings with different TiC content on the surface of 45 steel using TiC powder and CoCrNi alloy powder as cladding materials. The phase composition and microstructure of the coating were studied by X-ray diffractometer (XRD), scanning electron microscope (SEM) and metallographic microscope (OM). The microhardness, friction and wear properties and corrosion resistance of the coating were measured. The results show that the phase of the coating was mainly composed of FCC solid solution phase when the content of TiC was 0%similar to 5%. The phase of the coating was composed of TiC phase and FCC solid solution phase when the content of TiC was 15%similar to 25%. TiC particles in the shape of irregular polygons, spheres and cross petals were uniformly dispersed in the coating. Due to the second phase strengthening effects of TiC, the average microhardness of the coating reaches the maximum value 401.5 HV0.3, which is about twice the hardness of the substrate 45 steel, and the minimum weight loss is 2.6 mg when the content of TiC was 25%. The wear form of the coating is mainly abrasive wear. With the increase of TiC content, the corrosion resistance of the coating decreases and then increases. The corrosion resistance of the coating is obviously better than 45 steel. When the content of TiC is 25%, the corrosion resistance of the coating is the best, the self-corrosion potential is -479.08 mV, the self-corrosion current density is 1.16x10(-4) mA.cm(-2). TiC/CoCrNi composite coatings possess excellent corrosion resistance and wear resistance, which can effectively improve the surface properties of 45 steel.
