Daimler-Benz Rockwell-C Adhesion Research Articles

Investigation on microstructure and mechanical properties of boron-modified 13Cr5Ni2Mo by powder-pack boriding

ABSTRACT The main objective of the present paper is to investigate the effect of pack boriding treatment at 950°C/4 h on surface 13 Cr supermartensitic stainless steel. Scanning electron microscopy and X-ray diffractometry were used to characterise the grown boride layers microstructures. In addition, we performed 3D profilometry, microhardness measurements, nanoindentation tests with a Berkovich diamond tip, Daimler-Benz Rockwell-C adhesion, and ball-on-disk wear tests in order to evaluate the mechanical properties. After boriding, the phases were found to be iron borides (FeB/Fe2B), chromium borides (CrB), nickel borides (Ni2B), and molybdenum borides (Mo2B). The results showed that the use of the powder-pack boriding process on 13Cr SMSS at 950°C/4 h conducted in the presence of dual phases (FeB/Fe2B) improved the mechanical properties compared to untreated material.

Investigation of the effect of boriding on the wear behaviour of AISI 1050 carbon steel

In this study, AISI 1050 carbon steel samples were boronized with the powder pack boriding technique at 875°C for 2, 4 and 6 hours using Ekabor 2 boriding powder. The boride layer thicknesses obtained with the boriding time increased and after 2, 4 and 6 hours of boriding, a 30.6, 40.0 and 71.8 µm boride layer, predominantly composed of Fe2B phase, was obtained. Boride layers were formed in tooth-like morphology. Thanks to this boride layer, the surface hardness of the substrate was improved 6.2-6.4 times and a maximum surface hardness of 1543.8 HV was reached. With the Daimler-Benz Rockwell-C adhesion tests, it was determined that the adhesion quality of the boride layer was generally at the HF1 level. With the boriding carried out, the specific wear loss of AISI 1050 steel was reduced from 421.25 mm3/Nm x10-6 to 17.67 mm3/Nm x10-6, and the wear resistance was increased approximately 24 times.

(Cr1-xAlx)N Coating Deposition by Short-Pulse High-Power Dual Magnetron Sputtering.

The paper deals with the (Cr1-xAlx)N coating containing 17 to 54 % Al which is deposited on AISI 430 stainless steel stationary substrates by short-pulse high-power dual magnetron sputtering of Al and Cr targets. The Al/Cr ratio in the coating depends on the substrate position relative to magnetrons. It is shown that the higher Al content in the (Cr1-xAlx)N coating improves its hardness from 17 to 28 GPa. Regardless of the Al content, the (Cr1-xAlx)N coating manifests a low wear rate, namely (4.1-7.8) × 10-9 and (3.9-5.3) × 10-7 mm3N-1m-1 in using metallic (100Cr6) and ceramic (Al2O3) counter bodies, respectively. In addition, this coating possesses the friction coefficient 0.4-0.7 and adhesive strength quality HF1 and HF2 indicating good interfacial adhesion according to the Daimler-Benz Rockwell-C adhesion test.

Tribological and adhesion properties of microwave-assisted borided AISI 316L steel

Abstract In this study, AISI 316L stainless steel alloy samples were borided with powder-pack boriding method using Ekabor II powder with the support of a microwave furnace with a power of 2.9 KW and a frequency of 2.45 GHz. Boriding was carried out at 850, 900 and 950 °C temperatures for 2, 4 and 6 h of operation. A distinct diffusion barrier consisting of Fe–Ni–Si elements was detected in borided samples at 950 °C for 4 and 6 h. As a result of the Daimler Benz Rockwell-C adhesion tests, regions with insufficient adhesion strength were detected in these samples. In other samples, adhesion qualities between boride layers and substrate were in the range of HF1–HF3. The lowest specific wear rates were determined as 5.208 (mm3 Nm−1) × 10−6 and 5.210 (mm3 Nm−1) × 10−6 for the samples borided for 6 h at 850 °C and 4 h at 900 °C, respectively. It was determined that the increase in thickness of the brittle FeB compound increased the wear with the three-body abrasive wear mechanism.

The effects of boriding process on tribological properties and corrosive behavior of a novel high manganese steel

• Borided HMS unexpectedly exhibited saw-tooth morphology. • Borided HMS has superior adhesion properties. • Boriding increases service life, wear and corrosion resistance of HMS. In this study, wear and corrosion behavior of a novel borided high manganese steel (HMS) produced by the researchers was investigated. After the sheets were cold-rolled, they were annealed. HMS was borided at 850, 900, and 950 °C for 2, 4, and 6 h through the pack-boriding process. Borided HMS uncommonly exhibited a saw-tooth morphology like low alloy steels due to similar crystal structures of MnB and FeB. XRD analysis showed the existence of SiC, FeB, MnB and Fe 2 B phases. The present study indicated a silicon-rich zone by EDX mapping. The formation mechanism of silicon-rich zones was explained and expressed with the term “compact transfer of silicones”. The boriding time and temperature increased the thickness of the boride layer from 26.13 μm to 109.04 μm. The highest hardness value was observed in sample 5 (1757 HV 0.05 ). The activation energy of borided HMS was quite low compared to several high alloy steels in the literature. Daimler-Benz Rockwell-C adhesion test showed that adhesions of borided HMS surfaces were sufficient. The "egg-shell effect" that emerge due to the high silicon rate did not occur. In the wear tests applied under 5, 10, and 15 N loads, the borided HMSs exhibited a better wear resistance compared to the base metal (BM). However, the wear test was applied under 5 N load and BM had a better performance than several borided HMSs because of the phase transformations. In general, the borided samples had lower corrosion rates compared to the unborided ones.

Wear Behavior of Borided Cold-Rolled High Manganese Steel

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.

Adhesive Behavior of the Pack-Borided AISI 304L Steel with Microwave Hybrid Heating

Pack-boriding was applied to AISI 304L stainless steel material at temperatures of 850, 900 and 950 °C for 2, 4 and 6 hours with microwave hybrid heating method. The morphology of the boride layer formed on the surface of the samples was examined by optical microscope, and the phases formed in the layer were determined by XRD. The analysis of the adhesive strength of the boride layer to the substrate material was carried out by the Daimler-Benz Rockwell-C adhesion test. The tests were repeated at least 3 times for each of the pack-borided samples at all process temperatures and times. After the adhesion tests, macro and SEM images of indentation traces were taken. By analysing the indentation craters, it has been determined whether the damages are acceptable or not with reference to the VDI 3198 standard. The indentation craters formed on the pack-borided AISI 304L stainless steel sample surfaces at 850 °C with microwave hybrid heating method in all process times, for 2 and 4 hours at 900 °C, and 2 hours at 950 °C have the best adhesion quality in the HF1 category of the VDI 3198 norm.

Evaluation of Chromium Carbide Coatings on AISI 52100 Steel Obtained by Thermo-Reactive Diffusion Technique

In this study, chromium carbide coating obtained by thermo-reactive diffusion (TRD) process on AISI 52100 steel, prepared by packed method at temperature of 850 °C for 2, 4, 6 and 8 h, were investigated by performing a series of tests. The chromium carbide coating was characterized by scanning electron microscopy, X-ray diffraction (XRD), Micro-Vickers hardness test and Daimler-Benz Rockwell-C adhesion test. The chromium carbide layer produced on the AISI52100 steel exhibited a smooth and flat morphology. Depending on treatment time, the coating had a thickness of 3.2 – 8.5 μm. XRD analysis revealed the existence of Cr7C3 and (Cr,Fe)7C3 compounds. The hardness of the surface was increased from 723 to 1730 – 1920 HV0.025 after the coating process. The adhesion strength quality of the coating is correlated to HF2 to HF3 according to the VDI 3198 norm. Comparision of wear performance between chromium carbide coating and substrate showed that the coating can significantly improve wear resistance of the material. Friction coefficient decreased from the 0.46 to 0.37 and wear weight loss decreased by 89.3 %.

Investigation of Wear and Adhesion Behaviors of Borided Steels

In this study, AISI P20, H13 and D2 steels were pack borided at 900 and 950 °C for retention times of 2, 4 and 6 h. The boride layer thickness values changed depending on the chemical composition of the steels. The hardness of borides that formed on the surface of AISI P20, AISI H13 and AISI D2 steels were 1897 HV(50 g), 1989 HV(50 g) and 1916 HV(50 g), respectively. On the other hand, the Vickers hardness values of the untreated steels were 532 HV(50 g), 485 HV(50 g) and 408 HV(50 g), respectively. The adhesion properties of the boride layer were analyzed by performing the Daimler–Benz Rockwell-C adhesion method. According to the adhesion and wear test results, the adhesion and wear resistance of the boride layer decreased with the increase in the boriding temperature and time.

Characterization and Rockwell-C adhesion properties of chromium-based borided steels

In this study, adhesion properties of boride layers formed on the surface of AISI 52100, AISI 5140, AISI 440C, AISI 420 and AISI 304 steels were investigated. Boronizing treatment was carried out in Ekabor-II powders at the temperatures of 850 and 950 °C for 4 h. The properties of boride layers were evaluated by optical microscopy, SEM, X-ray diffraction and micro-Vickers hardness tester. The Daimler-Benz Rockwell-C adhesion test was used to assess the adhesion of boride layers. Test result showed that adhesion of boride layers depended on the dual-phase structure. The stresses at the FeB/Fe2B interphase caused delamination failure and poor interphase adhesion with increase in the depth of hard and brittle FeB-based layer.

The effect of Na2S2O3 on RE-boronizing behavior of 45 carbon steel

In this study, the effect of Na2S2O3 on RE-boronizing behavior of 45 carbon steel was investigated by varying the Na2S2O3 content in the treatment agent. The content of Na2S2O3 was set to 0%, 1%, 2%, 3%, 4% and 5%, respectively, to study the effect of sulfur on the property of the boride layer. The diffusion layers obtained by the above-described agents containing different levels of Na2S2O3 were named B-0SL, B-1SL, B-2SL, B-3SL, B-4SL and B-5SL, respectively. Pack RE-boronizing of 45 carbon steel was carried out at 300°C for 2h, and then at 850°C for 6h. The diffusion coatings were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), Vickers microhardness measurement, profilometry, the Daimler-Benz Rockwell-C adhesion test, and friction test. Testing results have revealed a significant morphology change in the borides with different Na2S2O3 contents. The thickness of the layer increases dramatically with increasing content of Na2S2O3, reaches its maximum (152μm) with an agent of 3wt.% Na2S2O3, then remains unchanged with further increasing Na2S2O3 content. The concentrations of B, S and O in the diffusion coatings increase with increasing the content of Na2S2O3. B-rich, O-rich and S-rich regions form successively from the surface to the inner layer in the B-5SL layer. FeS2 and Fe2O3 phases with a low hardness were observed in the B-3SL and B-5SL layers, respectively. The microhardness of the B-5SL layer is the highest, while the adhesion between the coating and the substrate in the B-3SL layer is the best among all the coatings. Compared with other coatings, the B-3SL layer can still keep a lower friction coefficient as well as a lower wear rate even when a high load is applied.

Non-conventional photocathodes based on Cu thin films deposited on Y substrate by sputtering

Copper (Cu) thin films were deposited on yttrium (Y) substrate by sputtering. During the deposition, a small central area of the Y substrate was shielded to avoid the film deposition and was successively used to study its photoemissive properties. This configuration has two advantages: the cathode presents (i) the quantum efficiency and the work function of Y and (ii) high electrical compatibility when inserted into the conventional radio-frequency gun built with Cu bulk. The photocathode was investigated by scanning electron microscopy to determine surface morphology. X-ray diffraction and atomic force microscopy studies were performed to compare the structure and surface properties of the deposited film. The measured electrical resistivity value of the Cu film was similar to that of high purity Cu bulk. Film to substrate adhesion was also evaluated using the Daimler–Benz Rockwell-C adhesion test method. Finally, the photoelectron performance in terms of quantum efficiency was obtained in a high vacuum photodiode cell before and after laser cleaning procedures. A comparison with the results obtained with a twin sample prepared by pulsed laser deposition is presented and discussed.

Comparison of the properties of Pb thin films deposited on Nb substrate using thermal evaporation and pulsed laser deposition techniques

Pb thin films were prepared at room temperature and in high vacuum by thermal evaporation and pulsed laser deposition techniques. Films deposited by both the techniques were investigated by scanning electron microscopy to determine their surface topology. The structure of the films was studied by X-ray diffraction in θ–2θ geometry. The photoelectron performances in terms of quantum efficiency were deduced by a high vacuum photodiode cell before and after laser cleaning procedures. Relatively high quantum efficiency (>10−5) was obtained for all the deposited films, comparable to that of corresponding bulk. Finally, film to substrate adhesion was also evaluated using the Daimler–Benz Rockwell-C adhesion test method. Weak and strong points of these two competitive techniques are illustrated and discussed.

Adhesion and wear properties of boro-tempered ductile iron

In this study, adhesion and wear properties of boro-tempered ductile iron (BDI) were investigated. Boro-tempering was carried out on two stage processes i.e. boronizing and tempering. At the first stage, ductile iron samples were boronized by using pack process at 900 °C for 1, 3, and 5 h and then, secondly tempered at 250, 300, 350, and 400 °C for 1 h. X-ray diffraction (XRD) analysis of boro-tempered samples showed that FeB and Fe 2B phases were found on the surface of the samples. The Daimler-Benz Rockwell-C adhesion test was used to assess the adhesion of boride layer. Test result showed that adhesion decreased with increasing boriding time and increased with increasing tempering temperature. Dry sliding wear tests of these samples were performed against Al 2O 3 ball at a constant sliding speed and loads of 5 and 10 N. Wear tests indicated that boro-tempering heat treatment increased wear resistance of ductile iron. In addition, it was found that while wear rate of boro-tempered samples decreased with increasing boriding time, there is no significant affect of tempering temperature on wear rate.

Mechanical properties evaluation of chromized tungsten carbide–cobalt hardmetals

Chromizing treatment has shown promising potential applications in the mechanical industry due to the excellent corrosion and mechanical properties provided by this process. However, the application of a chromizing process on the tungsten carbide–cobalt hardmetals has never been reported in literature. In this work, the pack chromization process has been adopted on tungsten carbide–15 wt.% cobalt (WC–15Co) hardmetals to produce a chromium containing hard surface layer. The scanning electron microscopy (SEM) and X-ray diffractometer (XRD) were employed to analyse the surface and cross-sectional morphologies and crystalline phases of chromized materials, respectively. The mechanical properties of the chromized tungsten carbide–cobalt hardmetal were evaluated by nanoindentation, Daimler-Benz Rockwell-C adhesion, scratch and pin-on-disk wear tests. It was observed that the chromizing layer was around 2 to 10 μm in thickness, which consisted of a thin (Cr,Fe) 2 N 1 − x phase in the outermost region and an underlying (Cr,Fe) 23C 6 phase after the chromization process held at 950 °C for 1 to 9 h. The hardness of the chromized hardmetals was improved effectively. In general, surface cracks on the chromizing layer should be avoided to maintain adequate mechanical properties, such as a high fracture toughness of the coating. It is concluded that the high hardness, sufficient adhesion quality and excellent wear resistance coatings were achieved by the pack chromizing process on the WC-15Co hardmetals held at 950 °C for 1 and 9 h.

Identification of Delamination Failure of Boride Layer on Common Cr-Based Steels

Adhesion is an important aspect in the reliability of coated components. With low-adhesion of interfaces, different crack paths may develop depending on the local stress field at the interface and the fracture toughness of the coating, substrate, and interface. In the current study, an attempt has been made to identify the delamination failure of coated Cr-based steels by boronizing. For this reason, two commonly used steels (AISI H13, AISI 304) are considered. The steels contain 5.3 and 18.3 wt.% Cr, respectively. Boriding treatment is carried out in a slurry salt bath consisting of borax, boric acid, and ferrosilicon at a temperature range of 800–950 °C for 3, 5, and 7 h. The general properties of the boron coating are obtained by mechanical and metallographic characterization tests. For identification of coating layer failure, some fracture toughness tests and the Daimler-Benz Rockwell-C adhesion test are used.

The mechanical properties evaluation of the CrN coatings deposited by the pulsed DC reactive magnetron sputtering

The chromium nitride coatings have been deposited by the bipolar symmetric pulsed DC reactive magnetron sputtering process at different temperature and pulse substrate bias. The pulse frequencies of target power and the substrate bias were kept at 2 kHz and 50 kHz, respectively. The nanoindenter, scratch and Daimler-Benz Rockwell-C adhesion tests were adopted to evaluate the mechanical properties of the CrN coatings. The preferred orientation of the CrN coatings changed from (111) to (200) with increasing substrate temperature and negative bias voltage applied. The hardness and adhesion properties of the coatings also increased with substrate temperature and a − 290 V bias voltage. A CrN film with 21 GPa in hardness and good adhesion property was deposited at 300 °C and − 290 V bias. It is observed that through the bipolar symmetry pulsed DC reactive magnetron sputtering process, the CrN films with sufficient adhesion performance was achieved in this work.

Tribological properties evaluation of AISI 1095 steel chromized at different temperatures

Pack chromization process provides a surface modified coating on steel surface with high hardness, corrosion and temperature resistance. AISI 1095 carbon steels were chromized to form chromium–iron nitride and carbides on surface by pack cementation process at 850 and 900 °C for 1–9 h, respectively. Chromized layer with an outer (Cr,Fe) 2N 1- x and inner (Cr,Fe) 23C 6 and (Cr,Fe) 7C 3 phases were observed. The wear resistance of chromized steels was evaluated by pin-on-disk wear tests. Daimler–Benz Rockwell-C adhesion and scratch tests were further conducted to evaluate the adhesion properties of chromized layers. Surface morphologies of chromized layers and matrix after wear and adhesion tests were studied with an electron probe microanalyzer. Chipping and microradial cracking failures were revealed on the chromized layers after the Daimler–Benz Rockwell-C adhesion tests. The adhesion strength quality of chromized layers was related to HF1–HF4. The critical loads increased with the chromizing temperature and time. It is concluded that the adhesion properties and tribological properties of chromized layers were improved as chromizing temperature and time increased. A chromizing process held at 850/900 °C for 4 h is then proposed for the AISI 1095 steel to achieve the optimal tribological performance.

Mechanical property evaluation of cathodic arc plasma-deposited CrN thin films on Fe–Mn–Al–C alloys

Chromium nitride is a promising hard coating applied in forming, drawing and plastic molding industries due to its good thermal stability and excellent resistance to wear and corrosion. An austenitic Fe–30Mn–5.8Al–1C alloy was coated with a CrN film by a cathodic arc plasma deposition process. The mechanical and adhesion properties were evaluated by microhardness, scratch, nanoindentation, Daimler–Benz Rockwell-C adhesion and pin-on-disk wear tests. The microhardness of CrN film reaches 2310±100 HK under a 10-gf load. The elastic modulus of the CrN film is 290 GPa, measured with a nanoindenter under a 3000-μN load. The adhesion of CrN film deposited on Fe–Mn–Al–C substrate is observed to be better than HF1. The wear resistance of the Fe–Mn–Al–C substrate is also significantly improved by the presence of the CrN film.