Melting of multipass surface tracks in steel incorporating titanium carbide powders

Materials Science and Technology

2015

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An overlapping composite track coating was produced on a steel surface by preplacing an 0.5 mm thick layer of TiC powder and then melting using a TIG torch of constant energy input. The influence of the overlapping operation on preheating of the substrate, the dissolution of TiC particulates and the subsequent depth and hardness of the composite layer was analysed. The melt microstructure consisted of both undissolved and partially dissolved TiC particulates, together with a variety of morphologies and sizes of TiC particles precipitated during solidification. Preheating, resulting from the overlapping operation occurred, producing additional melting of the TiC particulates and deeper melt depths but with a reduced volume fraction of TiC precipitates in the subsequent tracks. A maximum hardness of over 800 Hv was developed in the composite layer. The high hardness was unevenly distributed in tracks melted at the initial and final stages, while it varied across the melt depths in other tracks.

Section: Microstructurementioning

confidence: 99%

Overlapping tracks processed by TIG melting TiC preplaced powder on low alloy steel surfaces

Materials Science and Technology

2015

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“…More recently, a TIG torch technique has been explored for the surface modification of steels as a much cheaper option to lasers [5][6][7][8]. Previous studies have shown that the hardness of low alloy steels increased significantly when TiC in the form of powder, was incorporated through laser cladding [8] and the TIG melting technique [9][10][11].The development of improved wear resistance through the incorporation of SiC particles to produce metal matrix surface composites is well established in aluminum and titanium alloys by laser surface engineering [12][13][14].With the exception of work by Terry and Chinyamakobvu [15],who studied the effect of an addition of SiC particles on the wear properties of steel, little attention has been paid to using SiC particles in iron and steels for this purpose. Majumdar et al [16], attempted to develop a compositionally gradient SiC dispersed phase to improve the wear properties of mild steel, through laser cladding.…”

Section: Introductionmentioning

confidence: 99%

Effect of silicon carbide particle size on microstructure and properties of a coating layer on steel produced by TIG technique

Muñoz‐Escalona

Advances in Materials and Processing Technologies

2016

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Surface engineering is essential to prolong life of engineering components subject to deterioration in service from wear, erosion or corrosion, separately or in combination. This is possible by, for example, incorporating ceramic particles into a molten substrate surface, which may result in the partial or complete dissolution of the particles, and precipitation of a new phase, giving enhanced surface protection. Here, a single track surface zone of a micro-alloyed steel, was preplaced with a layer of SiC particles, with 1 or 75 µm in size, melted at a constant heat input, with a tungsten inert gas (TIG) torch, using argon as shielding gas. The aim was to compare the melted track without SiC particles and when using SiC particles on the generated temperature, microstructure, melt dimension and hardness of the re-solidified surfaces. Previous work has shown that microstructural changes occur along the track length due to preheating of the un-melted surface ahead of the molten zone. This effect was explored by inserting thermocouples along the 300mm length of steel. By optimizing the process parameters, a resolidified melt layer free of porosity has been achieved with 75 µm size SiC particles. This melt reached a maximum hardness of 750 HV.

“…Furthermore, when a number of overlapping tracks are laid down to cover the surface, differences in microstructures have been reported to produce changes in hardness through the melt depth. For example, temperature increases greater than 500°C have been recorded between the first and final tracks for both titanium alloys [11,12] and steels [13,14]. These changes can also influence the surface roughness.…”

Section: Introductionmentioning

confidence: 99%

Effect of shielding gas on the properties and microstructure of melted steel surface using a TIG torch

Escalona

Advances in Materials and Processing Technologies

2015

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This version is available at https://strathprints.strath.ac.uk/49507/ Strathprints is designed to allow users to access the research output of the University of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (https://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to the Strathprints administrator: strathprints@strath.ac.ukThe Strathprints institutional repository (https://strathprints.strath.ac.uk) is a digital archive of University of Strathclyde research outputs. It has been developed to disseminate open access research outputs, expose data about those outputs, and enable the management and persistent access to Strathclyde's intellectual output. Abstract. A surface engineering technique based on a Tungsten Inert Gas (TIG) torch was used to melt single tracks on the surface of a micro-alloyed steel with a hardness of 150 HV. The influence of three shielding gases, argon, helium and nitrogen, on the microstructure and hardness of the resolidified surfaces was analyzed. Effect of Shielding Gas on the Properties andIn all melting techniques, the heat generated by the source is normally conducted to the substrate ahead of the torch, and has been described as 'preheat'. This leads to a gradually higher substrate temperature, from the start to the finish of a melted surface track. The aim of this research was to analyze any inhomogeneities in the microstructure, due to 'preheat', which is rarely considered in the published literature. Three thermocouples were located along the melted track in order to record the temperature at three different points. An energy input of ~ 840J/mm was used in each experiment and the results show that the maximum temperature recorded by the last thermocouple, N o three (subjected to the preheat), for argon, helium and nitrogen gas was 590 ºC, 1120º C and 740 ºC respectively, where a difference of 150 ºC and 200 ºC was registered between the first and third thermocouples when using helium and nitrogen respectively. The corresponding hardness values were 170 HV, 162 HV and 225 HV, and the corresponding surface roughness values were 6 µm, 12 µm and 25µm. A decrease of almost 60% in the roughness value was observed between the initial and last stage of the melted track, when using argon as shielding gas.