Influence of Microstructure and Chemical Composition on Microhardness and Wear Properties of Laser Borided Monel 400

Abstract

In this study, wear properties of Monel 400 after laser alloying with boron are described. Surfaces were prepared by covering them with boron paste layers of two different thicknesses (100 µm and 200 μm) and re-melting using diode laser. Laser beam power density was equal to 178.3 kW/cm2. Two laser beam scanning velocities were chosen for the process: 5 m/min and 50 m/min. Surfaces alloyed with boron were investigated in terms of wear resistance, and the surface of untreated Monel 400 was examined for comparison. Wear tests were performed using counterspecimen made from steel 100Cr6 and water as a lubricant. Both quantitative and qualitative analysis of surfaces after wear test are described in this paper. Additionally, microstructures and properties of obtained laser alloyed surfaces are presented. It was found that the wear resistance increased from four to tens of times, depending on parameters of the laser boriding process. The wear mechanism was mainly adhesive for surfaces alloyed with initial boron layer 100 µm thick and evolves to abrasive with increasing boron content and laser beam scanning velocity. Iron particles detached from counterspecimens were detected on each borided surface after the wear test, and it was found that the harder the surface the less built-ups are present. Moreover, adhered iron particles oxidized during the wear test.

The Effect of Varying Parameters of Laser Surface Alloying Post-Treatment on the Microstructure and Hardness of Additively Manufactured 17-4PH Stainless Steel

“…Consequently, surface laser alloying is widely used not only for different stainless steels, such as 1.4550 [12], 17-4PH [14], and 316L [16,17], but also for a variety of other steels, for example, 41Cr4 steel [18], C45 steel [19], 145Cr6 tool steel [20], Vanadis-6 tool steel [21,22], and so on. The use of amorphous boron is important in laser surface alloying, and this has been confirmed in the above-cited works and some others [23,24].…”

Laser Processing of Diffusion Boronized Layer Produced on Monel® Alloy 400—Microstructure, Microhardness, Corrosion and Wear Resistance Tests

“…After diffusion, the specimens were cleaned from powder residues and degreased using acetone. The advantage of using the diffusion boriding process in comparison to the application of precoat in the form of paste [23][24][25] is the maintenance of a constant thickness on the entire surface of the specimen. In addition, the thickness of the diffusion layer can be controlled by extending or reducing the diffusion time.…”

“…In the publications that are available, the authors managed to find a single publication discussing diffusion boriding of Ni-Cu alloys [21]. Publications typically focus on the use of boron as a component of the additive material (powder) used in the laser cladding process (laser alloying [22][23][24][25], laser cladding [26,27]). In [27], a NiCrSiB coating was produced on Monel 400 using a laser cladding method, which was to improve resistance to cavitation erosion and corrosion.…”

“…They also found that resistance to cavitation erosion and corrosion was significantly improved. In [22][23][24][25], the influence of boron introduced into the Ni-Cu alloy by means of a laser beam was studied; cracks at the border of laser tracks were found to be a certain drawback when creating a layer on Monel in laser boriding.…”

Study of the Relationship between Entropy and Hardness in Laser Cutting of Hardox Steel

“…Kukliski studied laser-treated samples of Monel 400 coated with boron. He found that alloying hardens the surfaces [ 41 ]. Mehrpouya showed that the microstructure of the H13 tool steel changed after laser treatment in the reworked layer, HAZ, and base metal.…”