Ali Günen

Investigation of Microabrasion Wear Behavior of Boronized Stainless Steel with Nanoboron Powders

In this study, 304 stainless steel was boronized using nano boron powders using a solid-state box boronizing technique. Boronizing processes were carried out at temperatures of 950 and 1000°C for 2 and 4 h of treatment. Nano boron was used as a source of boron and KBF4 salt was used as an activator. The boxes in which boron was processed were made of 304 stainless steel plates. A free-ball microabrasion test was performed on the boronized samples. Silicon carbide (SiC) abrasive powders (5 μm) were used in the abrasion experiments. The ball rotational speed was 73.7, 102.5, and 147.4 rpm in the free-ball microabrasion test. Boronized steels showed an improvement in abrasive wear resistance. Microstructures and wear surfaces of the samples were inspected using scanning electron microscopy (SEM) and optical microscopy. It was observed from SEM and optical examinations that boronizing time and temperature had an important effect on the thickness of the boride layer on steel surfaces. The presence of boride formed in the boride layer at the surface of the steels was determined by X-ray diffraction (XRD) analysis and (FeB, Fe2B) iron boride phases were observed. The microhardness values of the iron borides was up to 1626 HV. The abrasion rate for the boronized samples was quite high for abrasive and adhesive conditions due to a brittle layer with a nonuniform crystalline structure on the outer surface. Microchannels and rolling abrasions, which are characteristic of microabrasion, were determined as the abrasion mechanism.

Microabrasion Wear Behavior of Fast-Borided Steel Tooth Drill Bits

ABSTRACT In this study, the surface of steel tooth drill bits (Ni-Cr-Mo based) was subjected to the solid-state boriding treatment with 10- to 50-nm nanoboron powder. Boriding processes were carried out at a constant temperature of 1273 K for 30, 45, 60, 75, 90, and 105 min using a solid-state box boriding technique. Borided drill bit samples were characterized by conventional methods (microstructure, microhardness, X-ray diffraction, and chemical analysis). The wear behavior of borided samples was tested at different loads and sliding speeds by a microabrasion experimental setup. Metallographic studies showed that the boride layers have a sawtooth morphology and consist of FeB and Fe2B. The thickness and hardness of the boride layer were 35.29–202.56 μm and 1300–2333 HV0.1, respectively, depending on the duration. The wear resistance of borided samples increased significantly due to the increase in surface hardness and lubricating effect, both of which were caused by the boriding process. A groove wear mechanism prevailed in borided samples, whereas that of bare steel tooth drill bits (STDBs) was grooving, rolling, and mixed.

Effect of the powder particle size on the wear behavior of boronized AISI 304 stainless steel

Abstract In this study, the AISI 304 steel specimens were boronized with nanoboron of the size of 10–50 nm and commercial Ekabor 3 powders (<1400 μm) at 950 °C to 1000 °C for 2 h and 4 h. Boronized steel specimens were characterized via SEM, microhardness and XRD analyses. Abrasive wear behavior of the specimens, boronized at different temperatures and treatment durations, were examined. The fixed ball micro-abrasion tests were carried out using the abrasive slurry, prepared with different SiC powder particle sizes on the boronized specimens at different rotational speeds. The specimens boronized with nanoboron powders exhibited a higher hardness and abrasive wear resistance than the samples boronized with the Ekabor 3 powders.

The investigation of corrosion behavior of borided AISI 304 austenitic stainless steel with nanoboron powder

In this study, corrosion behavior and mechanical properties of AISI 304 austenitic stainless steel, which was borided with Nanoboron powder, was investigated. The commercially available steel was subjected to a boriding treatment with a size of 10–50 nm Nanoboron powders, at the temperatures of 1223 K to 1273 K with boriding durations of 2 to 4 h. Microstructure characterization of the steel was carried out with optical microscopy, scanning electron microscopy, microhardness and X-ray diffraction analyses. Corrosion tests were made by static immersion into a 10% H2SO4 acid solution and weight loss calculations as well as salt spray tests were carried out in accord with the ASTM B-117 standard. Boriding thermal treatment, increased the corrosion resistance of the steel against the acid solution, up to about 4.3 times while in the salt spray tests, weight loss corrosion resistance increased up to tier 2. However, anti-corrosion resistance decreased by 40%, its untreated value.

The effect of process conditions in heat-assisted boronizing treatment on the tensile and bending strength characteristics of the AISI-304 austenitic stainless steel

In this study, AISI 304 austenitic stainless steel surface was boronized with nanoboron and ekabor-III powders at 950 and 1000°C for 2 and 4 hours period by solid-state box boronizing method. Then, behaviors of the boronized specimen in the microstructure, three-point bending, and tensile strength characteristics were investigated. As a result of the boriding process, the boride layer thickness in the range of 23–67 µm and microhardness value in the range of 1020–2200 HV have been obtained according to the increase in processing time and temperature and to the particle size of the boron source (0, 1). The coating layer on boronized specimens did not exhibit any sign of reaction caused by the tensile strength applied until the yield point was in both tests. Although the particle size of the boron agents was more effective on the boronized specimen’s bending and tensile strength behaviors, it was observed that processing temperature and its duration are effective as well.

Investigations on Machinability of Al 2 O 3 Reinforced Al6061 Metal Matrix Composites

In this study, six different MMCs containing Al6061 matrix and Al 2 O 3 reinforcements with particle sizes of 32 µm and 66 µm and weight fraction of 10%, 15% and 20% were produced using the vortex method. Machinability tests were conducted at different feed rates and cutting speeds to determine the surface roughness and cutting forces. Result of the tests indicated that the cutting forces positively correlated with the feed rates. Increasing in the cutting speed result in decrease in the cutting forces. The cutting forces did not remarkably vary with respect to the particle size for the same feed rates. The surface roughness negatively correlated with the particle weight fraction. Better surface qualities were obtained at lower feed rates and higher cutting speeds.