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1

Effect of chemical composition of boriding agent on the optimization of surface hardness and layer thickness on AISI 8620 steel by solid and liquid boriding processes

Kul Mehmet, Yılmaz Yasin, Oskay Kürşad Oğuz, Kumruoğlu Levent Cenk

Advances in Materials Science

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2022

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Vol. 22, nr 3(73)

14--22

EN

Surfaces of cam shafts made of AISI 8620 steels were hardened by boriding processes in both solid and liquid mediums. Various chemical agents were used to achieve boride layers on the surfaces of the cam shafts in these processes. It was aimed to examine effects of the chemical agents on microhardness and thickness of the boride layers obtained. It was concluded that a bath composition of 5% B4C-90% SiC-5% KBF4 was appropriate for the hardest and thickest boride layer achieved in the solid medium, and a composition of 70% Na2B4O7-30% B4C in the liquid medium.

2

Microstructural characterization of borided Co-Cr-Mo alloy

Ucar Nazim, Gülüstan Can, Calik Adnan

Advances in Materials Science

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2021

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Vol. 21, nr 4(70)

90--98

EN

This study involves the effect of boriding powder composition on the microstructure and hardness of a CoCrMo alloy borided in a solid medium using the powder pack method. To investigate the effect of boriding powder composition, two different commercial boriding agents, Ekabor-HM and Ekabor III, were thoroughly mixed with ferrosilicon powders to form the boriding media. The CoCrMo samples were tightly packed with the Ekabor-HM and Ekabor III boriding powders in stainless steel containers to minimize oxidation. The boriding process was carried out under atmospheric conditions for 9 h in an electrical resistance furnace preheated to 1223 K. X-ray diffraction (XRD) analyses revealed that the surfaces of the borided CoCrMo alloys consisted of a bilayer composed of CoB and Co2B phases and also contained minor amounts of CrB, Mo2B5, and Mo2B. The average thickness of the boride layer in the samples borided with Ekabor HM and Ekabor III powders was 28±4.1 μm and 21±2.3 μm, while the average hardness of the boride layer was 1752±5.3 HV0.1 and 1364±3.8 HV0.1, respectively.

3

Structure, mechanical properties and corrosion behavior of boronized surface layer formed on AISI 321 stainless steel

Jagielska-Wiaderek K., Bala H., Swadźba L.

Ochrona przed Korozją

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2014

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nr 7

248--251

EN

Studies under microstructure, mechanical- and electrochemical corrosion properties of the boronized, AISI 321 acid resistant stainless steel have been presented. The process of the steel surface modification with boron has been carried out in a temperature of 900oC using long-lasting (6 h) gas-contact method in Ekabor-II powder containing potassium fluoroborate (KBF4) activator and alumina (filler). The thickness of the boron-rich layer has been evaluated on the basis of microhardness tests on the cross section of the surface layers. The extraordinary strong hardness of boronized layers is accompanied with a distinct increase in surface roughness and significant development of its area. The electrodes for the corrosion tests had a shape of rotating disks (RDE electrodes). The corrosion behavior of the outer boronized layer has been examined in acidified (pH = 2) aqueous sulphate solution, using potentiodynamic polarization technique. Unlike unmodified steel, the boron-rich outer layer does not passivate but undergo fast dissolution both in active- and transpassive regions in the corrosion solution.

PL

Przedstawiono wyniki badań mikrostruktury, właściwości mechanicznych i korozyjnych powierzchniowo naborowywanej, kwasoodpornej stali nierdzewnej typu X6CrNiTi18-10. Proces modyfikowania powierzchni stali za pomocą boru przeprowadzano stosując długotrwałą (6 h), kontaktowo-gazową metodę nasycania w mieszaninie proszkowej zawierającej Ekabor-II, fluoroboran potasu (KBF4) jako aktywator i tlenek glinu (wypełniacz). Grubość warstwy wzbogaconej w bor oceniano na podstawie testów mikrotwardości na przekroju poprzecznym modyfikowanych warstw stali. Niezwykle wysokiej twardości warstwy naborowanej towarzyszy znaczna jej porowatość i rozwinięcie powierzchni. Badania korozyjne wykonane z użyciem wirujących elektrod dyskowych. Zachowanie korozyjne zewnętrznej, naborowanej warstwy oceniono w zakwaszonym (pH = 2), siarczanowym roztworze wodnym, stosując polaryzacyjną technikę potencjodynamiczną. W przeciwieństwie do niemodyfikowanej stali, wzbogacona w bor jej warstwa zewnętrzna nie pasywuje się w roztworze korozyjnym, ale ulega szybkiemu roztwarzaniu zarówno w zakresie aktywnym jak i transpasywnym.

4

Wpływ naborowywania stali 50HS na wybrane właściwości warstwy wierzchniej i odporność na zużycie

Płonka S., Kusiński J., Suliga I.

Inżynieria Materiałowa

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2002

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R. XXIII, nr 5

336-339

PL

W pracy przedstawiono wyniki badań wpływu obróbki cieplnej i cieplno-chemicznej na strukturę geometryczną powierzchni, kinetyczny współczynnik tarcia przędzy oraz mikrotwardość warstwy wierzchniej prowadników ze stali 50 HS przędzarek obrączkowych. Zamieszczono wyniki przemysłowych badań odporności na zużycie prowadników naborowanych oraz hartowanych i odpuszczanych do twardości 400 HB przy przerobie przędzy będącej mieszaniną: 30% elana+70 % wełna oraz 80% argona + 20% bawełna. Stwierdzono, że zastosowanie naborowywania umożliwia ponad 13-krotny wzrost odporności badanych prowadników na zużycie.

EN

The paper describes results of heat treatment and thermochemical treatment of an investigation of the influence of heat treatment and thermomechanical treatment on geometrical structure of surface, kinematical friction coefficient of yarn and microhardness of guides surface layer made of 50HS steel. The results of industrial investigations of boronized, hardened and tempered to hardness of 400 HB yarn guides after production of 30% elana+70% wool and 80% argona+20% cotton are presented. Investigations show that boronizing allows to increase the life time of the yarn guides 13 times.

5

Modification of diffusion coatings structure by laser heat treatment.

Przybyłowicz K., Depczyński W., Mola R.

Inżynieria Materiałowa

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1998

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R. XIX, nr 4

1043-1046

EN

The effect of laser heat treatment (LHT) of selected steel grades after various chemical heat-treatments (CHT) on the structure and microhardness has been investigated. The specimens were subjected to following CHTs: boronizing (45), silico-boronizing (50HS) and chromizing (NC6). The LHT has been carried out by means of CO2 laser beam of maximum output of 6 kW and applied power 1200-2000 W at scanning rate 500 - 700 mm/min. Considerable refining and homogenization of the structure have been observed. It has been stated that LHT can eliminate the negative effects of the CHT (coarse grain and low hardness of the substrate).

6

Influence of the boride coatings on wearability of the yarn guide.

Płonka S., Suliga I., Trybalska B., Kusiński J.

Inżynieria Materiałowa

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1998

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R. XIX, nr 4

1108-1111

EN

The effectiveness of bath boronizing, hardening and tempering on the lifetime of the yarn guides has been studied. Examinations showed significant improvement of yarn guide lifetime after boronizing. Even that the boronized yarn guides were tested during almost 3 times longer time (20800 hrs) their mean degree was more than 13 times lower than that of conventionally treated ones whose were tested during the time of 7700 hrs.

7

Formation and properties of borided layers obtained using the glow discharge conditions on nickel thermally sprayed substrate.

Sobiecki J.R., Sawicki R.

Inżynieria Materiałowa

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1998

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R. XIX, nr 4

1081-1084

EN

The present paper describes the conditions of plasma boriding thermally sprayed nickel coatings. The results of metallographic, phase composition investigations, scanning electron microscopy, electron probe microanalysis, wear and corrosion resistances are compared. The combination of two different methods of producing surface layers has given possibilities of obtaining unique layers of good wear and corrosion resistances.