Effects of laser heat treatment of steel following diffusion chromizing

2017 ◽  
Vol 2 (83) ◽  
pp. 49-56
Author(s):  
I. Bauer ◽  
M. Paczkowska
Keyword(s):  
Heat Treatment ◽  
Surface Layer ◽  
Laser Treatment ◽  
Powder Mixture ◽  
Laser Heating ◽  
Optical Emission ◽  
Emission Spectrometry ◽  
Laser Heat Treatment ◽  
Diffusion Chromizing ◽  
Laser Heat

Purpose: This paper presents the findings of a study of laser heat treatment of C45 steel following diffusion chromizing. The aim of the study was to assess the effect of laser heating of steel subjected on the microstructure of its surface layer. Design/methodology/approach: Diffusion chromizing was conducted at the temperature of 1050°C for 8 hours in a LABOTHERM LH15/14 laboratory furnace. A powder mixture of the following composition was used to produce the layer: Cr2O3 with an addition of Al, kaolin and an activator – ammonium chloride NH4Cl. Diffusion chromizing of C45 steel was followed by laser heat treatment with a dual diode TRUDISK 1000 laser device. The treatment was carried out in four variants with a laser beam of 400 to 900 W. The microstructure of the surface layer was assessed with a scanning electron microscope Tescan Vega 5135. Hardness tests were carried out by the Vickers method on crosswise microsections. The chemical composition of the diffusion layer was assessed by optical emission spectrometry. Findings: The results revealed the presence of a modified surface layer following laser heat treatment in each of the variants. Research limitations/implications: This study focuses on the effect of laser heating of C45 steel subjected to diffusion chromizing on the microstructure of its top layer. Presented research are the first step of the investigation of the surface layer of steel after diffusion chromizing and laser treatment. Next one will be consisted in detailed investigation of microstructure (phases identification) of the achieved surface layer using (among other methods) X-ray diffraction. Practical implications: Laser heat treatment of C45 steel after diffusion chromizing can be applied to parts of machines and devices used in various branches of industry exposed to tribological wear and corrosion. Originality/value: The results of the experiment were affected by the composition of the powder mixture and process parameters of the diffusion chromizing and the laser treatment.

Laser Surface Modification of Borochromizing C45 Steel

2012 ◽  
Vol 57 (1) ◽  
pp. 211-214 ◽  
Author(s):  
A. Bartkowska ◽  
A. Pertek ◽  
M. Jankowiak ◽  
K. Jóźwiak
Keyword(s):  
Heat Treatment ◽  
Surface Layer ◽  
Surface Modification ◽  
Laser Power Density ◽  
Laser Surface ◽  
Laser Heat Treatment ◽  
Laser Surface Modification ◽  
Scanning Rate ◽  
Melted Zone ◽  
Laser Heat

Laser Surface Modification of Borochromizing C45 SteelIn this study the test results for borochromized C45 steel after laser surface modification were presented. Influence of laser heat treatment on the microstructure and microhardness of surface layer was investigated. The process of borochromizing consisted of chromium plating followed by diffusion boronizing. The laser heat treatment (LHT) of multiple tracks in the helical line was carried out with CO2laser beam. The technological laser TRUMPF TLF 2600 Turbo CO2of the nominal power 2.6 kW was applied. Borochromizing was carried out with laser power density q = 41.40 kW/cm2and at laser beam scanning rate v = 0.67 m/min and v = 2.016 m/min. Measurements of microhardness were conducted using the Vickers' method and Zwick 3212 B hardness tester. Microstructure observations were performed by means of an optical microscope Metaval Carl Zeiss Jena and scanning electron microscope Tescan VEGA 5135. After laser heat treatment with re-melting a three-zone layer was obtained, which included: re-melted zone, heat affected zone and a core. Influence of laser treatment parameters on thickness of melted zone and microstructure of the surface layer was tested. The microhardness tested along the axis of track of the surface layer after laser modification was about 800-850 HV. The results of tests showed influence of laser power density and scanning rate on microstructure and properties of borochromized layers.

Improving the Properties of Magnetic Bearing Shaft Material by HVOF Coating of WC-Metal Powder and Laser Heat Treatment

2012 ◽  
Vol 560-561 ◽  
pp. 1052-1058 ◽  
Author(s):  
T.Y. Cho ◽  
Y.K. Joo ◽  
J. H. Yoon ◽  
H. G. Chun ◽  
S.H. Zhang
Keyword(s):  
Heat Treatment ◽  
Metal Powder ◽  
Laser Heating ◽  
Surface Hardness ◽  
Magnetic Bearing ◽  
Free Carbon ◽  
Laser Heat Treatment ◽  
Friction Coefficients ◽  
Hvof Coating ◽  
Laser Heat

Abstract. Micron-sized WC-metal (WC-0.6%C-21%Cr-6%Ni) powder was coated onto the substrate of magnetic bearing shaft material Inconel718 (substrate or In718) using JK3500 HVOF thermal sprayer for the improvement of the surface properties of the substrate. The optimal coating process for the highest surface hardness was obtained using the Taguchi experimental program. The coating was laser heat-treated (LH) by CO2(g) laser for further improvement of the properties. During the thermal spraying, a small portion of metal carbides of powder decomposed to W2C, metals and free carbon. The free carbon reacted with excessively sprayed oxygen, and formed carbon oxide gases, forming porous coating. By laser-heating, porosity decreased and the porous strips at the interface of coating and substrate (coat/sub) compacted. At the interface, the precipitated graphite concentration decreased and the metal elements diffused from both the coating and substrate increased, enhancing the functions as buffer zone and increasing adhesion of coating. The surface hardness of substrate increased by coating and further increased by laser-heating from 410±30 Hv to 983±101 Hv and 1425±94 Hv respectively. Porosity of coating decreased by laser-heating from 2.6±0.4% to 0.35±0.06%, and coating thickness shrank from 280㎛ to 200㎛. Friction coefficients of substrate decreased from 0.52±0.02 to 0.36±0.04 by coating, because the free carbon formed by decomposition of WC to W2C functioned as a solid lubricant. By increasing sliding surface temperature from 25°C to 450°C, the friction coefficients of substrate and coating were decreased from 0.52±0.02 to 0.31±0.02 and from 0.36±0.04 to 0.23±0.04 respectively, because of easy formation of free carbon and metal oxides which functioned as solid lubricants. Wear depth of surface was decreased by coating and by LH coating from 55µm to 32 µm and to 12 µm respectively. HVOF coating of WC-metal powder on In718 surface and laser heat-treatment of the coating are highly recommended for the improvement of the properties of magnetic bearing shaft.

Enhancing Mechanical Properties and Formability of AISI 301LN Stainless Steel Sheet by Local Laser Heat Treatment

2013 ◽  
Vol 554-557 ◽  
pp. 885-892 ◽  
Author(s):  
Antti Järvenpää ◽  
Matias Jaskari ◽  
Pentti Karjalainen ◽  
Mikko Hietala
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Laser Beam ◽  
Laser Treatment ◽  
Strength Properties ◽  
Coarse Grained ◽  
Laser Heat Treatment ◽  
Austenite Grain Size ◽  
Laser Heat ◽  
Ultrafine Grained

This study demonstrates applying local laser heat treatment to produce ultrafine-grained austenite (UFGA) structures in an AISI 301LN type commercial austenitic steel. Pieces of 50% cold-rolled sheets containing more than 90% strain-induced martensite were heated locally by a laser beam to various peak temperatures to obtain different degrees of martensite reversion to austenite. Mechanical properties and formability of grain-refined and coarse-grained structures were measured by tensile and Erichsen cup tests. In addition to standard Erichsen cup test, additional interrupted tests were carried out, where cups were first stretched close to the critical strain. Drawn cups were then heated locally by a laser beam to revitalize the structure and thereby enhance the formability in the following cupping test until failure. Results showed that local laser heat treatment is suitable for the reversion treatment to refine the austenite grain size. Various structures were produced: completely reverted microstructures (T > 700 °C) with grain sizes 0.9 - 2 µm in addition to partially reverted structure (T < 700 °C) containing nano- and ultrafine-grained austenite (0.6 µm) with some martensite. The grain refinement by local annealing improved the strength properties. The Erichsen cup tests showed that the formability was equal in the completely reverted ultrafine-grained structures to that of the coarse-grained sheets. It was demonstrated that the local laser treatment restored formability of the drawn cups, allowing stretching to be continued. The second forming step after the laser-treatment provided an enhancement of 19 and 14% in the cup depths in coarse-grained and ultrafine-grained steels, respectively, even though the laser-treatment parameters were not optimized yet.

scholarly journals Increasing wear and corrosion resistance of steel products by combined laser thermomechanical treatment

2021 ◽  
Vol 6 (1 (114)) ◽  
pp. 72-80
Author(s):  
Oleksandr Danyleiko ◽  
Vitaliy Dzhemelinskyi ◽  
Dmytro Lesyk
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Surface Layer ◽  
Thermomechanical Treatment ◽  
Shot Peening ◽  
Laser Heat Treatment ◽  
Dynamic Surface ◽  
Laser Heat ◽  
Wear And Corrosion ◽  
Wear And Corrosion Resistance

A technique is presented for hardening metal products, in particular, the main tools (hammers) and cases of core drilling bits made of steel 30HGSA, using thermomechanical surface treatment according to a separate scheme. The method of combined laser thermomechanical hardening used in the study consists in the use of shot peening followed by laser heat treatment. Its use makes it possible to increase the operational properties of steel products, in particular, their wear and corrosion resistance. Based on the results of theoretical and experimental studies, the paper substantiates the features of dynamic surface plastic deformation for the analysis of impact during shot peening. The advantages of using laser hardening without surface melting are presented. Experimental research methods are proposed for determining the structural-phase composition, structure of the surface layer, hardness and microhardness of the hardened zones of steel 30HGSA. The range of rational modes of impact shot peening and thermal laser treatment has been determined. A device for testing samples for wear resistance has been developed. Methods of testing for wear and corrosion resistance of the surface of samples are proposed for assessing the tribological properties and contact interaction of materials under quasi-static and dynamic loading conditions. It is concluded that rational technological modes of hardening tools made of steel 30HGSA using combined laser thermomechanical treatment allow increasing the depth of the hardened layer by ~1.5 times compared to laser heat treatment. In addition, they provide the microhardness of the surface layer of ~5400 MPa, which is ~2.5 times higher than the microhardness of the base material

HVOF Coating of µ-WC-Metal Powder and Laser Heat-Treatment of the Coating for the Improvement of Turbo Shaft Material

2012 ◽  
Vol 586 ◽  
pp. 74-79
Author(s):  
T.Y. Cho ◽  
Y.K. Joo ◽  
J.H. Yoon ◽  
H.G. Chun ◽  
S.H. Zhang
Keyword(s):  
Heat Treatment ◽  
Metal Powder ◽  
Laser Heating ◽  
Wear Behavior ◽  
Substrate Surface ◽  
Surface Hardness ◽  
Thermal Spraying ◽  
Laser Heat Treatment ◽  
Hvof Coating ◽  
Laser Heat

A hybrid surface treatment was performed to improve the surface properties and the durability improvement of turbo shaft material Inconel718. A micron sized (µ) WC-metal powder (86% WC 10% Co 4% Cr) was coated onto a substrate surface using HVOF thermal spraying, and the coating was heat treated by a CO2 laser. With the HVOF coating of the powder onto the substrate, the surface hardness of substrate increased approximately 300% from 399 Hv to 1260±30 Hv, and further increase of approximately 40% from1260±30 Hv to 1820±100 Hv by laser heating the coating for 0.6 s. Porosity of coating decreased more than five times from 2.2±0.3% to 0.4±0.1% by laser heating. According to the reciprocating sliding test, friction and wear behavior of coating improved by coating for both sliding surface temperature of 25°C and 450°C. Therefore, the HVOF coating and laser heat treatment of coating are recommended for the durability improvement of turbo shaft materials.

Optimization of the Case Depth of a Cylinder Made With 4340 Steel by a Control of the Laser Heat Treatment Parameters

2018 ◽  
Author(s):  
Rachid Fakir ◽  
Noureddine Barka ◽  
Jean Brousseau
Keyword(s):  
Heat Treatment ◽  
Numerical Model ◽  
Surface Temperature ◽  
Laser Power ◽  
Case Depth ◽  
Maximum Temperature ◽  
Laser Heat Treatment ◽  
Laser Heat ◽  
4340 Steel ◽  
Cylindrical Workpiece

This paper presents a numerical model able to control the temperature distribution along a 4340 steel cylinder heat-treated with Nd: YAG laser. The numerical model developed using the numerical finite element method, was based on a study of surface temperature variation and the adjustment of this temperature by a control of the heat treatment laser power. The proposed analytical approach was built gradually by (i) the development of a numerical model of laser heat treatment of the cylindrical workpiece, (ii) an analysis of the results of simulations and experimental tests, (iii) development of a laser power adjustment approach, and (iv) proposal of a laser power control predictor using neural networks. This approach was made possible by highlighting the influence of the fixed (non-variable) parameters of the laser heat treatment on the case depth, and has shown that it is possible by controlling the laser parameters to homogenize the distribution of the maximum temperature reached on the surface for a uniform case depth. The feasibility and effectiveness of the proposed approach leads to a reliable and accurate model able to guarantee a uniform surface temperature and a regular case depth for a cylindrical workpiece of a length of 50-mm and with a diameter of between 16-mm and 22-mm.

Sub-millisecond post exposure bake of chemically amplified resists by CO 2 laser heat treatment

2010 ◽  
Author(s):  
Byungki Jung ◽  
Jing Sha ◽  
Florencia Paredes ◽  
Christopher K. Ober ◽  
Michael O. Thompson ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Laser Heat Treatment ◽  
Post Exposure ◽  
Chemically Amplified ◽  
Laser Heat ◽  
Post Exposure Bake ◽  
Chemically Amplified Resists

The preparation and performance of grain size gradient TWIP steel fabricated by laser heat treatment

2019 ◽  
Vol 743 ◽  
pp. 294-300 ◽  
Author(s):  
Kun Wang ◽  
Aiping Wei ◽  
Zimu Shi ◽  
Xizhang Chen ◽  
Jixing Lin ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Grain Size ◽  
Twip Steel ◽  
Laser Heat Treatment ◽  
Laser Heat ◽  
And Performance ◽  
Size Gradient
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