scholarly journals Boron Diffusion in Steel 20

2020 ◽  
pp. 58-62
Author(s):  
E.P. Shevchuk ◽  
V.A. Plotnikov ◽  
G.S. Bektasova
Keyword(s):  
Liquid Glass ◽  
High Hardness ◽  
Ammonium Hydroxide ◽  
Boride Layer ◽  
Boron Diffusion ◽  
Volumetric Heating ◽  
High Refractoriness ◽  
The Matrix ◽  
Steel 20 ◽  
Diffusion Mass

As is known, boriding is carried out to increase the wear resistance and corrosion resistance of iron-carbon alloys. Along with high hardness, borides, unfortunately, have very high fragility and high refractoriness. An effective way to counter the fragility of boride layers is to form a composite structure consisting of inclusions of solid borides in a more plastic matrix. Such coatings can be obtained by volumetric heating in a muffle furnace using a boron paste that besides a mixture of iron and boron powders contained ammonium hydroxide and activated carbon with or without liquid glass. Boriding of a surface is carried out at high temperatures =1000 °С for 5 minutes. It is experimentally found that the microhardness of the surface layer increased by about 30% compared with the microhardness of the substrate, and that the thickness of the boride layer depends on the presence of liquid glass in the coating. It has been established that specially calculated proportions of ammonia, liquid glass, and charcoal contribute to the formation of an extensive diffusion zone of iron borides, the formation of which is due to the anomalously high diffusion mass transfer of boron into the matrix.

Enhanced Surface Hardness by Boron Diffusion in Martensitic Stainless Steel via Cathodic Reduction and Thermal Diffusion Based Boriding (CRTD-Bor)

2015 ◽  
Vol 719-720 ◽  
pp. 25-28 ◽  
Author(s):  
G. Kartal Sireli ◽  
C. Yelkarasi ◽  
P. Ozkalafat ◽  
S. Timur ◽  
M. Urgen
Keyword(s):  
Thermal Diffusion ◽  
Single Phase ◽  
Surface Hardness ◽  
Boride Layer ◽  
Cathodic Reduction ◽  
Boron Diffusion ◽  
Cross Sectional ◽  
The Matrix ◽  
Enhanced Surface ◽  
Borided Steel

In this study, a developed new boriding method called as “Cathodic Reduction and Thermal Diffusion based Boriding” (CRTD-Bor) was applied to increase the surface hardness of 400 series steels. The cross-sectional examination of borided steel revealed that the boride layers consisted of single phase Fe2B. A dense and continuously 25μm thick Fe2B layer could be formed after 20 minutes of CRTD-Bor. The grown boride layer exhibited 1500±200 HV on top, and gradually decreased to the matrix (325 ± 25 HV).

scholarly journals Gas Technique of Simultaneous Borocarburizing of Armco Iron Using Trimethyl Borate

Coatings ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 564 ◽  
Author(s):  
Natalia Makuch ◽  
Piotr Dziarski ◽  
Michał Kulka
Keyword(s):  
Wear Resistance ◽  
Armco Iron ◽  
High Hardness ◽  
Outer Zone ◽  
Boride Layer ◽  
Boron Diffusion ◽  
Trimethyl Borate ◽  
Boron Source ◽  
Boriding Process ◽  
Favorable Conditions

The gas boriding process is an appropriate technique used for increasing the hardness and wear resistance of iron and steels. However, the boron halides (e.g., BCl3, BF3) are rarely used as a boron source during gas boriding in industry due to the toxic character of these reagents. The possibility of the use of organic compounds as a boron source in plasma assisted processes was the instigation to determine the possibility of applying these agents for gas boriding. In the present work trimethyl borate was used as an organic boron source. The use of a N2–H2–B(CH3O)3 atmosphere ensured the appropriate conditions for the simultaneous gas borocarburizing of Armco iron. The process was carried out at 1223 K (950 °C) for 2 h. The produced layer consisted of two zones: an outer zone containing a diffusion of boron atoms and an inner zone containing a diffusion of carbon atoms, under the outer zone. Due to the reduction of trimethyl borate with hydrogen, free atoms of carbon were released for the gas atmosphere. Therefore, there existed favorable conditions for carburizing. Unfortunately, the formation of a carburized layer was the reason for the difficult diffusion of boron atoms. As a consequence, the boron diffusion front was hindered, and the outer boride layer was relatively thin (ca. 7.8 µm). The boride layer contained only Fe2B phase, which was characterized by high hardness in the range from 1103 HV0.01 to 1546 HV0.01. The presence of iron borides in the outer layer was also the reason for increased wear resistance in comparison with untreated Armco iron.

scholarly journals Study of Diffusion Boride Bayers of Steel 20, Obtained by the Micro-Arc Surface

2020 ◽  
pp. 59-63
Author(s):  
E.P. Shevchuk ◽  
V.A. Plotnikov ◽  
G.S. Bektasova
Keyword(s):  
Boric Acid ◽  
Diffusion Zone ◽  
Composite Layer ◽  
High Hardness ◽  
High Strength ◽  
Heterogeneous Structure ◽  
Diffusion Coatings ◽  
The Matrix ◽  
Diffusion Boriding ◽  
Steel 20

We discuss the results of the study of carbon steel 20 boriding performed by the micro-arc chemical-thermal treatment of a mixture containing iron and boric acid. The study has been carried out in scientific laboratories of the EKSU named after S. Amanzholov. It is found out that boride diffusion coatings obtained by this method are characterized by high hardness of 3.5 GPa and have an extensive diffusion zone. The wide diffusion zone is a surface layer of steel in which the compounds of boron and iron are distributed so that a transition region is formed between the hardened region and the matrix. The material of the diffusion zone is a composite consisting of a plastic а-phase of iron and high strength iron borides. X-ray diffraction studies revealed the formation of Fe3B compounds. It is found that the most optimal composition of the mixture contains iron and boric acid in a ratio of 1:3 (Fe-25% + H3BO3-75 %). The use of the micro-arc surfacing method makes it possible to intensify the process of diffusion boriding in comparison with traditional methods. Also, it ensures that a hardened composite layer with a heterogeneous structure formed by the diffusion-crystallization mechanism is developed on a surface of steel products.

Thermally Sprayed Quasicrystal Composite Coatings for Bearings and Other Friction Threaded Applications

2000 ◽  
Author(s):  
E. Lugscheider ◽  
C. Herbst-Dederichs ◽  
A. Reimann
Keyword(s):  
Composite Coatings ◽  
High Hardness ◽  
Atmospheric Plasma ◽  
Ductile Material ◽  
Metallurgical Analysis ◽  
The Matrix ◽  
Material Forming ◽  
Alloy Properties ◽  
Thermally Sprayed ◽  
Sprayed Coatings

Abstract Quasicrystalline phases improve many alloy properties such as thermomechanical stability, thermal and electrical conductivity, and tribological performance. High hardness, however, is accompanied by brittleness, an undesired property in many applications. Reduced brittleness can be achieved by embedding quasicrystalline phases in a more ductile material, forming a metal-matrix composite that retains some quasicrystalline properties. This study evaluates thermally sprayed coatings made from different compositions of such composites. The coatings assessed were produced by arc-wire, HVOF, and atmospheric plasma spraying using various forms of feed material, including blended, agglomerated, chemical encased, and attrition-milled powders and filled wires. The investigation involved metallurgical analysis, proving the existence of quasicrystal content and assessing the matrix phase, and tests showing how sliding wear is influenced by the composition of quasicrystalline phases.

Properties of aluminum metal matrix composites manufactured by selective laser melting

2021 ◽  
Vol 112 (7) ◽  
pp. 552-564
Author(s):  
Christian Felber ◽  
Florian Rödl ◽  
Ferdinand Haider
Keyword(s):  
Additive Manufacturing ◽  
Aluminum Alloys ◽  
Selective Laser Melting ◽  
Metal Matrix ◽  
High Hardness ◽  
High Strength ◽  
Laser Melting ◽  
Scanning Calorimetry ◽  
Particle Reinforcement ◽  
The Matrix

Abstract The most promising metal processing additive manufacturing technique in industry is selective laser melting, but only a few alloys are commercially available, limiting the potential of this technique. In particular high strength aluminum alloys, which are of great importance in the automotive industry, are missing. An aluminum 2024 alloy, reinforced by Ti-6Al-4V and B4C particles, could be used as a high strength alternative for aluminum alloys. Heat treating can be used to improve the mechanical properties of the metal matrix composite. Dynamic scanning calorimetry shows the formation of Al2Cu precipitates in the matrix instead of the expected Al2CuMg phases due to the loss of magnesium during printing, and precipitation processes are accelerated due to particle reinforcement and additive manufacturing. Strong reactions between aluminum and Ti-6Al-4V are observed in the microstructure, while B4C shows no reaction with the matrix or the titanium. The material shows high hardness, high stiffness, and low ductility through precipitation and particle reinforcement.

scholarly journals Wear Behavior of Borided Cold-Rolled High Manganese Steel

Coatings ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1207
Author(s):  
Fatih Hayat ◽  
Cihangir Tevfik Sezgin
Keyword(s):  
Wear Behavior ◽  
Xrd Analysis ◽  
Boride Layer ◽  
Manganese Steel ◽  
Dry Sliding Wear ◽  
Low Alloy Steels ◽  
Boron Diffusion ◽  
High Manganese ◽  
High Manganese Steel ◽  
Boriding Process

In this study, a novel high-manganese steel (HMS) was borided at 850, 900 and 950 °C for 2, 4, and 6 h by the pack boriding process. Contrary to previous literature, borided HMS uncommonly exhibited saw-tooth morphology like low alloy steels, and manganese enhanced the boron diffusion. Another striking analysis is that the “egg-shell effect” did not occur. The present study demonstrated the silicon-rich zone for the first time in the literature by EDX mapping. Moreover, the formation mechanism of silicon-rich zones was explained and termed as “compact transfer of silicones (CTS)”. XRD analysis showed the existence of FeB, Fe2B, MnB and SiC phases. The boriding time and temperature increased the thickness of the boride layer from 31.41 μm to 117.65 µm. The hardness of the borided layer ranged from 1120 to 1915 HV0.05. The activation energy of borided HMS was found to be a very low result compared to high alloy steel investigated in the literature. The Daimler-Benz Rockwell-C adhesion test showed that adhesions of borided HMS surfaces are sufficient. The dry sliding wear tests showed that boriding treatment increased the wear resistance of untreated HMS by 5 times. The present study revealed that the boriding process extended the service life of HMS components.

Formation of boride layers on a commercially pure Ti surface produced via powder metallurgy

2021 ◽  
Vol 112 (4) ◽  
pp. 303-307
Author(s):  
Yavuz Kaplan ◽  
Mehmet Gülsün ◽  
Sinan Aksöz
Keyword(s):  
Powder Metallurgy ◽  
Substrate Surface ◽  
High Hardness ◽  
Titanium Boride ◽  
Boride Layer ◽  
Powder Metallurgy Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Commercially Pure ◽  
Boriding Process

Abstract In this study, powder metallurgy was applied in a furnace atmosphere to form titanium boride layers on a commercially pure Ti surface. Experiments were carried out using the solid-state boriding method at 900 °C and 1000°C for 12 h and 24 h. Samples were produced by pressing the commercially pure Ti powders under 870 MPa. The sintering process required by the powder metallurgy method was carried out simultaneously with the boriding process. Thus, the sintering and boriding were performed in one stage. The formation of the boride layer was investigated by field emission scanning electron microscopy, optical-light microscopy, X-ray diffraction, and elemental dispersion spectrometry analyses. In addition, microhardness measurements were performed to examine the effect of the boriding process on hardness. The Vickers microhardness of the boronized surface reached 1773 HV, which was much higher than the 150 HV hardness of the commercially pure Ti substrate. The X-ray diffraction analysis showed that the boriding process had enabled the formation of TiB and TiB2 on the powder metallurgy Ti substrate surface. Consequently, the production of Ti via powder metallurgy is a potentially cost-effective alternative to the conventional method, and the boriding process supplies TiB and TiB2 that provide super-high hardness and excellent wear and corrosion resistance.

Study on the Crack Forming during Cold Forging Process of ML25Mn Steel

2012 ◽  
Vol 184-185 ◽  
pp. 1255-1258
Author(s):  
Zhuang Li ◽  
Di Wu ◽  
Wei Lv
Keyword(s):  
Chemical Composition ◽  
Surface Quality ◽  
High Hardness ◽  
Complex Oxides ◽  
Cold Forging ◽  
Internal Defects ◽  
Forging Process ◽  
Sem Observation ◽  
Metallic Inclusions ◽  
The Matrix

The important factors that affect the formability of the cold forging steel are its surface quality and internal defects. The cracking phenomenon was taken place during cold forging of ML25Mn steel. In this study, microstructural analyses were made on around the cracked regions of the steel. The reason of cracking, which occurred during cold forging for ML25Mn steel, was investigated based on SEM observation in detail. The results have shown that the crack forming during cold forging process is not related to the chemical composition for ML25Mn steel. Cracking is not resulted from high hardness of the steel rods. There are some non-metallic inclusions in the matrix of ML25Mn steel, and the film-like inclusions are composed of MnS, CaS and complex oxides containing Mg, Al, Mn, Fe, S, Ca and O. The formation of non-metallic inclusions is the result of the deoxidation and the solidification during smelting and casting of steel.

Fatigue Characteristic of Spheroidal Vanadium Carbides Cast Iron

2010 ◽  
Vol 457 ◽  
pp. 279-284 ◽  
Author(s):  
Masahito Tanaka ◽  
Kazumichi Shimizu ◽  
Daijiro Ito ◽  
Toru Noguchi
Keyword(s):  
Cast Iron ◽  
Fracture Surface ◽  
Fatigue Fracture ◽  
Vanadium Carbide ◽  
High Hardness ◽  
Fatigue Characteristic ◽  
Matrix Microstructure ◽  
Secondary Cracks ◽  
The Matrix ◽  
Vanadium Carbides

The purpose of this study is to investigate the fatigue characteristic and fatigue fracture mechanism of the high V-Cr-Ni spheroidal carbide cast iron (SCI-VCrNi) with spheroidal vanadium carbide (VC) dispersed within austenitic stainless matrix microstructure. The SCI-VCrNi that has high hardness was developed by 10mass%V adding to 18-8 stainless steel with spheroidal VC is distributed in the matrix. Firstly from the plane bending, the fatigue limit σw has been found to the 358MPa of SCI-VCrNi. Secondly, fracture surface observations were performed to clarify the fatigue mechanism of SCI-VCrNi. The fracture surface of SCI-VCrNi was so rough that the beach mark could not be observed. So, SEM was employed to observe, the fatigue fracture surface which showed a particular fatigue pattern. Also, many fracture cracks of VC were observed. In addition, the secondary cracks are shown at the interface between VC and the matrix. It can be suggested that the bondability between VC and the matrix is strong, and therefore, the propagation of cracks was delayed by the breakage of VC.

Effect of Pack Boronizing on Microstructure and Microhardness of 304 Stainless Steel

2017 ◽  
Vol 740 ◽  
pp. 54-59
Author(s):  
Siti Khadijah Alias ◽  
Bulan Abdullah ◽  
Mahesh Talari ◽  
Muhammad Hafizuddin Jumadin ◽  
Mohd Faizul Idham ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Layer Thickness ◽  
Vickers Microhardness ◽  
Microstructural Analysis ◽  
Boride Layer ◽  
304 Stainless Steel ◽  
Boron Diffusion ◽  
Low Alloy Steel ◽  
Surface Protection ◽  
Selection Of

The implementation of boronizing in low alloy steel had been implemented tremendously in past years as this method offers excellent surface protection that led to enhancement of hardness and wear of the material. In conjunction to that, few parameters had been recognized as the factor that promotes boron diffusion into the surface of the material which is the selection of boronizing temperature and time. This study concentrated on the effect of pack boronizing on the boride layer thickness of 304 stainless steel which contained high amount of alloying elements. The microstructural analysis and boron layer thickness was measured and observed using optical microscopy and SEM analyzer. The microhardness of the material was measured using Vickers microhardness tester. The results portrayed that boronizing successfully induced boronizing layer containing FeB and Fe2B phases with thickness of 15μm. This resulted in major improvement of the microhardness values with improvement of 5 times compared to non-boronized samples.

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