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

Mateusz Kukliński,Aneta Bartkowska,Grzegorz Kinal,Damian Przestacki

doi:10.3390/ma13245757

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.

Highlights

Nowadays, non-ferrous alloys have an increasingly important role in industry and their properties are often modified with high-energy heat sources like laser beam [1,2,3]
Layers alloyed with boron paste 100 μm thick, which are shown in Figures 3a,c and 4a,c are built mainly of column crystals solidified in much directions which depend on turbulences of liquid metal during re-melting
Laser alloying with boron is an effective method for improving wear resistance of Monel 400 and level of this enhancement is strongly dependent on microhardness of obtained layers and on the laser boriding parameters

Summary

Introduction

Non-ferrous alloys have an increasingly important role in industry and their properties are often modified with high-energy heat sources like laser beam [1,2,3]. Laser processes, including laser alloying [4,5,6] and laser remelting [3] are increasingly displacing plasma processes [7] due to the fact that quality and properties of obtained layers are promising. Monel 400, which was laser treated in this study, is a one-phase nickel-copper alloy. Its main advantage is high corrosion resistance This alloy is generally applied in harsh environments, including seawater, alkalis, salts or acids. The main disadvantage of Monel 400 is its relatively low hardness in comparison with other nickel alloys [11]. Taking into consideration that products made from this material are often exposed to high flow rates, there is a risk of failures due to erosion, cavitation or wear

Methods

Results

Conclusion