Characterization and wear performance of boride phases over tool steel substrates (original) (raw)

Sliding and abrasive wear behaviour of boride coatings

Wear, 2004

Polyphase boride coatings constituted by an inner layer of Fe2B and an outer layer of FeB were thermochemically grown on iron and medium carbon steel by a pack cementation process. The tribological behaviour of borided samples was investigated under both sliding and abrasion testing conditions. Considerably different values of wear rate were found in different regions of the coatings. The

Tribological properties of oxidised boride coatings grown on AISI 4140 steel

Materials Letters, 2006

In this study, we investigated the wear behaviour of borided and borided + short-duration oxidized AISI 4140 steel. Boronizing was carried out in a slurry salt bath consisting of borax, boric acid and ferro silicon. Also, short-duration oxidizing treatment was applied to borided steel to produce glass-like boron oxide layer. The short-duration oxidizing was performed at 750°C for 3 min. Optical and scanning electron microscope (SEM) cross-sectional examinations of borided layer revealed a needle-shaped morphology. The presence of non-oxide boride type ceramics FeB and Fe 2 B formed on the surface of steel substrate was confirmed by classical metallographic technique and X-ray diffraction (XRD) analysis. The hardness of borides formed on the surface of steel substrate and unborided steel substrate were 1446-1690 HV 0.1 and 280 HV 0.1 , respectively. The wear behaviour of borided steel were characterised by using a pin-on-disc technique. The borided and short-duration oxidized steels, in the form of pins were allowed to slide against a hard AISI 440C stainless steel disc (63 HRc). The sliding velocity of 1 m s − 1 for borided and short-duration oxidized steel and the nominal load on the pin was 20 N. The highest wear rates were observed on disc slide against the base steel, whilst the lowest wear rates occurred during sliding against the borided and short-duration oxidized steel surfaces. It was observed that the friction coefficient of unborided (hardened + tempered) and borided steels ranged from 0.50 to 0.60, but after short-duration oxidizing, the friction coefficient of borided steel was dropped to 0.12.

Dry sliding wear behavior of borided hot-work tool steel at elevated temperatures

Surface and Coatings Technology, 2017

In the present study, the surface of AISI H13 hot-work tool steel was borided with EKabor II powders using powder pack-boriding method. The process was carried out at 800, 900 and 1000 °C temperatures for 2, 4 and 6 h periods. The wear tests were carried out using a ball-on disc tribometer at room temperature and 500 ºC on borided and untreated AISI H13 hot-work tool steel. Scanning electron microscope (SEM), optical microscope, 3D profilometer, X-Ray diffraction analysis and micro-hardness tester were used in the evaluation of micro-structure and wear data. The increase in the boriding temperature and boriding period led to increased thickness and hardness of the boride layer. Boriding at 800 °C resulted with formation of Fe 2 B, Mn 2 B, Cr 5 B 3, phases, while FeB, Fe 2 B, Mn 2 B, and Cr 5 B 3 boride phases occurred at 900 and 1000 °C. Dominant wear mechanisms were microcrack-induced plastic deformation during high temperature wear tests; oxidation and microcrack formation during room temperature wear tests; and oxidation and severe plastic deformation for the untreated specimen.

Investigation of wear behavior of borided AISI D6 steel

Materiali in tehnologije, 2016

We have investigated the effect of the boriding process on the wear behavior of AISI D6 steel. The boride layer was characterized by light microscopy, X-ray diffraction and micro-Vickers hardness testing. The X-ray diffraction analysis of the boride layers on the surface of the steels revealed the existence of the FeB, Fe2B, CrB and Cr2B compounds. Depending on the chemical composition of the substrates, the boride-layer thickness on the surface of the AISI D6 steel was found to be 164.42 μm. The hardness of the boride compounds formed on the surface of the steels ranged from 1672 HV0.05 to 2118 HV0.05, whereas the Vickers hardness value of the untreated steels was 584 HV0.05. The wear tests were carried out using a ball-disc arrangement under dry-friction conditions at room temperature with an applied load of 10 N and a sliding speed of 0.3 m/s for a sliding distance of 1000 m. It was observed that the wear rate of the borided and unborided AISI D6 steel ranged from 1.28 × 10-6 to 81.2 × 10-6 mm 3 /Nm.

Investigation of Wear Behavior of Borided DIN 20MoCr4 Steel

In the present study, wear properties of borides formed on DIN 20MoCr 4 cementation steel have been investigated. The boride layer was characterized by optical microscopy, X-ray diffraction technique and the micro-Vickers hardness tester. X-ray diffraction analysis of boride layers on the surface of the steels revealed the existence of FeB and Fe 2 B compounds. Depending on the chemical composition of substrates, the boride layer thickness on the surface of the DIN 20 MoCr 4 steels was found to be 62.84 μm. The hardness of the boride compounds formed on the surface of the DIN 20MoCr4 steel ranged from 1475 to 1848 HV 0,05 , whereas Vickers hardness values of the untreated steels DIN 20MoCr 4 was 246 HV 0,05 , respectively. The wear tests were carried out in a ball-disc arrangement under a dry friction condition at room temperature with an applied load of 10N and with a sliding speed of 0.2 m/sec at a sliding distance of 500m. The wear surfaces of the steel were analyzed using a SEM ...

Wear Behavior of Borided AISI D2 Steel under Linear Reciprocating Sliding Conditions

Protection of Metals and Physical Chemistry of Surfaces, 2019

AISI D2 steel is the most commonly used cold-work tool steel in its grade. In this study, microstructural characterization and some mechanical properties of borided AISI D2 steel samples were investigated. The boriding treatment was carried out at 900 and 1000°C for 3, 5 and 7 hours by using Ekabor 2 powder and a solid-state box boriding technique. Wear behavior of borided and non-borided steel were conducted by linear reciprocating wear test using an Al 2 O 3 ball as the counterpart. The sliding distances and the sliding speed were remained constant at 250 m and 5 mm/s, respectively, with the loads of 10, 20 and 30 N (being applied). Microstructural characterization revealed homogeneous, dense and fine-grained structure which had predominant dual phase boride (FeB+Fe 2 B) layer with minor of Cr-B, MoB , V-B, Mn-B interstitial compounds being present as well. The thickness and hardness values of the boride layer were in the range of 46.23-126.8 μm and 2005-2227 HV 0.1 , respectively, depending on the process conditions. The results showed that the wear resistance improved by up to 6.7 times in comparison with non-borided AISI D2 steel. Severe plastic deformation was the effective wear mechanism in non-borided AISI D2 steel. However for the samples which were borided at 900 and 1000°C, delamination and polishing type of wear mechanisms were observed, respectively. Surface hardness and boride layer thickness had a great effect both on wear rate and wear mechanism.

Wear and surface characterization of boronized pure iron

Journal of Tribology, 2007

This research investigates the morphological nature and tribological behavior of boronized pure iron using experiments combined with theoretical analysis. Samples studied were 99.97% purity iron boronized for 4 h at 800°C, 875°C and 950°C, respectively. Diffusion of the borided layer was analyzed by measuring the extent of penetration of the boride to sublayers as a function of boriding time and temperature. The distribution of alloying elements from surface to interior was determined by using rf-glow discharge optical emission spectrometry. It was found that boron concentrated in the layer and the diffusion of B atoms was deeper than the layer itself. In tribological tests, friction and wear behavior under dry rolling with sliding (pseudo-rolling) and dry pure sliding conditions was investigated. The wear experiments were conducted using a modified linear reciprocating tribometer. A scanning electron microscope and atomic force microscope were used for worn surface characterization. It was found that boronizing at 875°C exhibited the best wear resistance among the samples tested. Higher wear resistance was correlated with growth of boride crystals along stronger (002) orientation. Surface grain size distribution after the boriding process was identified as an important factor for wear resistance. Different fracture and wear modes were investigated. Analysis of the wear debris gave an insight into the operative wear mechanisms. This research is beneficial in optimizing the parameters of the boronizing process to achieve better wear resistance under different contact modes.

Production and characterization of boride layers on AISI D2 tool steel

Vacuum, 2010

a b s t r a c t AISI D2 is the most commonly used cold-work tool steel of its grade. It offers high hardenability, low distortion after quenching, high resistance to softening and good wear resistance. The use of appropriate hard coatings on this steel can further improve its wear resistance. Boronizing is a surface treatment of Boron diffusion into the substrate. In this work boride layers were formed on AISI D2 steel using borax baths containing iron-titanium and aluminium, at 800 C and 1000 C during 4 h. The borided treated steel was characterized by optical microscopy, Vickers microhardness, X-ray diffraction (XRD) and glow discharge optical spectroscopy (GDOS) to verify the effect of the bath compositions and treatment temperatures in the layer formation. Depending on the bath composition, Fe 2 B or FeB was the predominant phase in the boride layers. The layers exhibited ''saw-tooth'' morphology at the substrate interface; layer thicknesses varied from 60 to 120 mm, and hardness in the range of 1596-1744 HV were obtained.