Investigation of the Technological Possibility of Laser Hardening of Stainless Steel 14Cr17Ni2 to a Deep Depth of the Surface

The article presents the results of a research of the process of laser hardening of steel 14Cr17Ni2 (AISI 431) by radiation of a high-power fiber laser LS-16. Assessment of the theoretically possible maximum depth in laser processing without additional beam transformations, the use of additional coatings and devices were shown. The results of experiments on increasing the depth of the hardened layer during laser processing by using scanning of the laser beam and optimally selected mode parameters without scanning are demonstrated. The influence of the number of passes on the depth of the hardened layer is investigated. The microstructure of hardened samples was studied and quantitative estimation of structural components was carried out. The microhardness of hardened samples at different modes of laser hardening was measured.

Influence of laser hardening on laser induced periodic surface structures on steel substrates

Laser-induced periodic surface structures (LIPSS) are used to structure surfaces for functionalization. Thus, hydrophilic states are generated using LIPSS. However, these nanostructures do not withstand mechanical loads and therefore cannot be used for most tribological applications. Within this work the approach of laser hardening of LIPSS is investigated. It is shown that laser hardening leads to an alteration of prior structured surfaces. That effects the wetting behaviour. The higher the laser power during hardening, the more increases the contact angle of a single droplet on the surface and the more the surface lacks in terms of wetting behaviour. This phenomenon is attributed to changes in LIPSS’ aspect ratio. A high ratio leads to low contact angles and is shifted to low values when the laser power increases resulting in high contact angles. Hence, it is concluded that the thermal load during laser hardening, and it’s influence on the wettability must be taken into account when LIPSS are subjected to laser hardening.

Laser Hardening of Unimax Stainless Steel

Nowdays, laser hardening of materials brings a comparative advantage over the conventional hardening technique. Fast cooling rate due to the heat distribution through its own bulk material, self-quenching property (rapid cooling without external water or oil), environmentally friendly characteristics since the procedure does not exhaust smoke, the localized heat input due to adjustable laser spot size to avoid distortion and minimum time to finish the operation are some of the advantages to mention. NIKO is a company specialized in making electrical products like socket outlets and switches by using injection molding techniques. Unimax is a kind of stainless steel used by the company to prepare some parts of the injection molding components like a Nozzle. This time, the company is using more and more fiber-reinforced polymers throughout their product line. These composites are far stronger than the polymer, but on the downside, the fibers are quite abrasive. The objective of this research was to harden the Unimax stainless steel using Nd:YAG (neodymium-doped yttrium aluminum garnet) laser technique. First, the laser transverse speed and spot size were identified as the primary process parameters. Then, the traverse speed of 100, 150 and 400 mm/min and spot size of 2164, 2169, 2288 and 2412 um were assigned with 3 replications. Afterwards, thermal simulation was done using COMSOL Multiphysics© followed by the real test on the metal bar. Therefore, the highest hardness of 650 HV was obtained at a speed of 150 mm/min and a spot size of 2169 um diameters. Finally, the corresponding depth of hardness and roughness values of 200 um below the surface and unmelt samples respectively were obtained. HIGHLIGHTS Laser hardening of materials brings a comparative advantage over the conventional hardening technique The laser transverse speed and spot size were identified as the primary process parameters. Afterwards, thermal simulation was done using COMSOL Multiphysics© followed by the real test on the stainless steel bar The depth of hardening and Vickers hardness (HV) increased with the smaller spot size and slow traverse speed of the ND:YAG laser, but this resulted in a melt on the surface of the hardened metal One of the problems of making products using injection molding techniques using fiber-reinforced polymers is the abrasive nature of the fibers which widen the injection nozzle GRAPHICAL ABSTRACT

Numerical simulation and experimental study on laser hardening process of the 42CrMo4 steel

The large diameter pitch bearing was made of steel 42CrMo4 and the laser hardening process was used to improve its surface properties. In this paper, a numerical approach which can predict the temperature field and the hardened depth is provided for the laser hardening process of the 42CrMo4 steel. According to the simplification of the raceway structure of pitch bearing, the finite element model was constructed using ABAQUS software. Based on the actual process parameters, the transient thermal analysis was accomplished and the distribution of temperature field is analyzed. The hardened depth is determined according to the proposed temperature range. Laser power, laser scanning speed, and spot diameter were considered as input parameters, the experimental studies were performed based on orthogonal design in order to study the effects of process parameters. The finite element model is validated. The surface roughness and microstructure studies on treated surfaces were conducted. Also the micro-hardness testing was performed. The results show that the laser hardening increases surface hardness by about 3.8 times than that of the base material. The three parameters of laser power, laser scanning speed, and spot diameter have a coupling effect on the surface treatment. The input laser power density is more important.

Development of Hardening Technology for Oil and Gas Pumping and Compressor Equipment Using Laser Hardening

This paper considers the results of modes testing for surface laser hardening. It also includes the development of compositions for light-absorbing coating for industrial application of laser hardening. The paper presents the influence of the light-absorbing coating on the structuring of the surface layer under laser hardening of medium-carbon alloy steel.

Laser Hardening of Stamps in the Conditions of a Large Engineering Company

The work addresses the possible use of a third-generation robotic complex with a fiber laser to restore and strengthen the working parts of the stamping rig in the conditions of a large engineering company. The method of restoring and fine-hardening of stamps from complex steels 5X2MNF, 4X5MFS with solid-state laser is justified. Economic analysis was carried out and the economic effect of the complex was described.