Steel Ball Indenter Research Articles

Influence of shielding gas flow on the TIG welding process using stainless steel 304 material

A common issue encountered with main heat exchanger equipment is improper operation, which can lead to the development of cracks in the stainless-steel pipes. The welding process alters the metal microstructure in the heat-affected zone, thereby affecting the mechanical properties of the welded joint. To mitigate this issue, TIG welding with argon shielding gas is employed. This method helps prevent oxidation and ensures the formation of a stable welding arc in 304 stainless steel, which is renowned for its excellent mechanical properties and corrosion resistance. The objective of this study is to evaluate the impact of variations in shielding gas flow on the mechanical properties of 304 stainless steel plates during the TIG welding process. The aim is to determine the optimal settings for producing robust and long-lasting welded joints. To assess the hardness of the welded joints, we employed a Brinell-type Hardness Tester FB-3000LC machine. A Brinell steel ball indenter measuring 5 mm on the HBW scale and applying a load of 125 Kgf was utilized. At a protective gas flow rate of 8 L/min, the average tensile stress was 44.72 N/mm², strain was 0.177, modulus of elasticity was 2518 MPa, and hardness was 99.712 HBW. Increasing the gas flow rate to 13 L/min resulted in an average tensile stress of 47.50 N/mm², strain of 0.189, elastic modulus of 2525 MPa, and hardness of 105.522 HBW. Further increasing the gas flow rate to 18 L/min led to an average tensile stress of 49.69 N/mm², strain of 0.192, modulus of elasticity of 2597 MPa, and hardness of 106.704 HBW. Based on the research findings, it was observed that the weld area exhibited an increase in hardness values due to the heat generated during the welding process. The use of protective gas flow during welding is deemed effective in producing well-formed welded joints, as it prevents fractures from occurring within the weld area during the tensile test process. The choice of protective gas is determined by the dimensions of the material plate.

Pengujian Kekerasan dan Keausan Kampas Rem Sepeda Motor

This study is to determine the hardness and wear of two original and local brake pads on motorcycle brakes by conducting rockwell hardness and wear tests. This test was conducted at the B4T Bandung Automotive Laboratory with results at a load of 60 Kgf, a steel ball indenter with a diameter of 1/12 inch. The results show that the average value of the local brake pad hardness level is 66.7 HR and the average value of the original brake pad is 84.93 HR proving that the highest level of hardness is found in the original brake pad. Wear testing that the original brake canvas sample initial weight 75 gr with 3 variable testing time namely test 1 around 4 minutes obtained 71 gr with eroded weight 4 gr, test 2 around 8 minutes obtained 69 gr with eroded weight 6 gr, test 3 around 12 minutes with weight 67 gr, test 3 around 12 minutes obtained 67 gr with eroded weight 8 gr local brake canvas initial weight 74 gr with 3 variable testing time namely test 1 around 4 minutes obtained 69 gr with eroded weight 5 gr, test 2 around 8 minutes obtained 60 gr eroded with eroded weight 14 gr, test 3 got 56 gr with eroded weight 18 gr, from both samples the results of wear testing that the original and local brake canvas found that the original canvas wear is harder than the local type of canvas.

An evaluation of the effect of different veneer materials on fracture resistance of zirconia core

Objective: this in vitro study was done to evaluate the effect of packable P60 composite and Tetric N-Ceram composite veneer material on fracture strength of zirconia cores. Material and Methods: Twenty four zirconium cores (Vita, Germany) with 0.7 mm thickness were fabricated by CAD/CAM technology and then subjected to air abrasion with 50µm of Al2O3. Cores were randomly divided into three groups according to veneering material (group A: control group sandblasted with 50 µm Al2O3 veneered by IPS E-max Ceram porcelain, group C: sandblasted with 50 µm Al2O3, etching with hydrofluoric acid and veneered with P60 composite, group E: sandblasted with 50 µm Al2O3, etching with hydrofluoric acid and veneered with Tetric N-Ceram composite). All crowns were subjected to fracture strength test in the testing machine, with load application by steel ball indenter and 0.5 mm/min. cross head speed. Results: statistical analysis was carried out utilizing one-way ANOVA, LSD. The results of fracture strength value test showed the highest mean value was registered for group (A), and the lowest mean for group (E). One-way ANOVA test represented that, there was a statistically high significant different among all groups. LSD results showed a high significant difference increase in fracture resistance for Group A at p value (*P<0.001 High significant). Conclusions: Within the limitation of this study, sandblasting zirconia core with 50 µm Al2O3 and veneering with conventional ceramic produced restoration with acceptable fracture resistance value. Keywords Composite resin; Fracture resistance; Hydrofluoric acid; IPS Emax ceram; zirconium oxide.

Effect of Endodontic Access Preparation on Fracture Load of Translucent versus Conventional Zirconia Crowns with Varying Occlusal Thicknesses.

To evaluate the effect of endodontic access hole preparation on fracture resistance of translucent zirconia (5Y) and conventional zirconia crowns (3Y) with varying occlusal thicknesses. Polymethylmethacrylate (PMMA) dies, representing a prepared tooth, were milled. Zirconia crowns with 1 mm thick axial walls and varying occlusal thicknesses were milled from 3Y (Cercon HT) or 5Y (Cercon XT) zirconia discs and sintered. 160 crowns were divided into 16 groups (n = 10 per group) based on the zirconia type (3Y, 5Y), occlusal thickness (0.5, 1.0, 1.5, 2.0 mm), and access hole preparation (with access hole, control). Crowns were cemented on the PMMA dies with resin-modified glass ionomer cement (Rely X Luting Plus) under constant weight (500 g) and thermocycled for 10,000 cycles. In half of the samples, following 5000 cycles of thermocycling, a uniform endodontic access hole was created using a diamond bur and restored immediately with resin composite (Filtek Supreme Ultra, 3M ESPE). The fracture resistance of the specimens was tested on an Instron 5566 universal testing machine with a stainless steel ball indenter (9.0 mm dia.) and the maximum load before failure was recorded as fracture load (N). Three-way ANOVA testing examined the effect of zirconia type, occlusal thickness, and access hole preparation on fracture loads of the crowns. Statistical tests were two-sided and significance level was set at 95% (α= 0.05). Fracture load was significantly affected by the type of zirconia, occlusal thickness, and access hole preparation (p < 0.001). Pairwise comparisons revealed that access hole preparation significantly reduced the fracture load of 3Y crowns with 0.5 or 1.0 mm of occlusal thickness and 5Y zirconia crowns with 0.5, 1.0, or 1.5 mm of occlusal thickness (p < 0.05). Increasing occlusal thickness reduced the effect of access hole preparation on fracture load. Type of zirconia, occlusal thickness, and access hole preparation had significant effects on the fracture load of zirconia crowns. The effect of endodontic access was significant on the 3Y and 5Y zirconia crowns with ≤1.0 and ≤1.5 mm occlusal thicknesses, respectively.

Effect of ceramic reinforcement on the properties of iron based metal matrix nanocomposites

The present paper reports the fabrication routes along with the recent development in the area of iron based metal matrix nanocomposites. A detailed discussion is done on iron (Fe) metal matrix nanocomposites reinforced with aluminum oxide (Al2O3) prepared using powder metallurgy (P/M) technique. Composites were prepared by sintering in an argon atmosphere in the temperature range of 900–1100°celsius for 1–3 h. Hardness test was conducted on a Rockwell Hardness Tester using 1/8” H scale steel ball indenter. Specimens were tested for wear and corrosion using pin on disc wear and friction testing machine and gamry electrochemical cell. With the addition of aluminum oxide the hardness number reached upto 79 HRH and the wear rate was found out to be as low as 0.3 mm3/Km. It was also revealed that with the addition of aluminum oxide, corrosion protection efficiency was 99.96% and cobalt doping further improved it to 99.99%.

Determining of the machine compliance using instrumented indentation test and finite element method

.At present time the importance of indentation measurements once again increases. As modern and perspective measurement method it allows to measure various mechanical properties while only needing micro volumes of materials. While standard hardness measurement methods examine only the plastic response of sampled material, Depth Sensing Indentation (DSI) testing is founded on real-time recording of applied force and resulting travel of indenter. This allows to evaluate both plastic and elastic response of examined material during the indentation process which in turn allows for calculation of various static material properties in very small volumes of samples. The big advantage of this approach is saving of time (especially on sample preparation), however the data analysis – and thus results – could be influenced by certain factors. Those worth noting are surface quality of the sample, wear of the indenter head, its shape and material, and also the compliance of testing machine’s frame. If we consider the frame of testing machine having non-zero compliance, inevitably there will occur not only displacement of indenter but also displacement of frame itself, especially noticeable while using high loads. This negatively influences the results of such measurement. This work’s aim is to calculate the compliance of test machine’s frame using Finite Element Method model and 1 mm in diameter steel ball indenter. The result of this work is addition of virtual spring to the FEM model and fine tuning of its stiffness. This should allow us to minimize the influence of frame’s compliance on the results of future measurements.

Effect of Quasi-Static Loading on the Composite Laminates

The low velocity impact is a common phenomenon which occurs in fiber reinforced polymer composite products like LPG cylinders, fighter aircraft fuel drop tanks, aircraft wing surfaces, sports goods etc. The consequences of low velocity impact will create a considerable damage and ultimately lead to a premature failure of the structure. Hence the polymer composites for engineering applications must be provided with a better design solution. From the literature survey it is observed that, the response of composite laminates subjected to quasi-static loading, exhibits similar results as that of low velocity impact. Polymer reinforced composites are poor in damage tolerance with better strength to weight ratio than conventional materials. However composite materials can be tailored to meet the design requirements by manipulating fiber orientations and laminae stacking sequence. In the present paper, principles of classical laminate theory are considered for analysis. FEM is implemented for thorough understanding of the failure mechanism of each laminate by layer wise. Simulated quasi-static loading tests and observed the layer wise distribution of transverse strain intensity. The experimental setup is designed and fabricated as per ASTM D 6264 standards. The E-glass/epoxy composite laminate is quasi-statically loaded at its center by a steel ball indenter of diameter 8.7mm and its response is measured by the degree of opacity or translucency in terms of interlaminar and intra-laminar damage area. The stacking sequence of composite laminates are chosen as [00/600]12, [00/750]12 and [00/900]12. The damage areas obtained from numerical analysis are in good agreement with experimental results.

Adhesion analysis of polycrystalline diamond films on molybdenum by means of scratch, indentation and sand abrasion testing

Diamond films have been grown by hot-filament chemical vapour deposition (CVD) on molybdenum substrates under different growth conditions. The films grown with increasing substrate temperatures show a higher interconnection of diamond grains, whereas increasing methane concentrations in the 0.5–4.0% range lead to a transition from micro- towards nanocrystalline films. X-ray diffraction analysis shows Mo2C interlayer formation. Indentation, scratch and sand erosion tests are used to evaluate the adhesion strength of the diamond films. Using steel ball indenters (∅ 750 μm), indentation and scratch adhesion tests are performed up to final loads of 200 N. Upon indentation, the load values at which diamond film failure such as flaking and detachment is first observed, increase for increasing temperatures in the deposition temperature range of 450–850 °C. The scratch adhesion tests show critical load values in the range of 16–40 N normal load for films grown for 4 h. In contrast, diamond films grown for 24 h at a methane concentration of 0.5% do not show any failure at all upon scratching up to 75 N. Film failure upon indenting and scratching is also found to decrease for increasing methane concentration in the CVD gas mixture. The sand abrasion tests show significant differences in coating failure for films grown at varying CH4/H2 ratios. In contrast to the other tests, here best coating performance is observed for the films deposited with a methane concentration of 4%.

Cracking and fracturing behaviors of industrial diamond plates

Ring cracking measurements have been made on millimeter thick industrial diamond plates by performing a reverse type of hardness test with a conventional steel ball indenter system. Cathodoluminescence (CL) measurements at the ring crack edges provided evidence of associated deformation. Follow-on fracture strength measurements were made by three-point bend testing of beams laser-cut from two materials to probe both microstructural influences and the effect of laser-drilled “via holes” (for electrical application). Expanded autographic records of the bend tests allowed estimation of elastic modulus values. The bend tests were modeled satisfactorily with an ANSYS finite element description. Fracture surface topography measurements made on the failed bend specimens of one material also provided indication of plastic deformation being associated with the diamond material cracking behavior.

On the hardness determination of fine grained concrete

Hardness tests of concretes are used, for the present, only for comparison, and the values of hardness obtained do not meet the requirements of reproducibility. An attempt has been made to develop an experimental method which could measure accurately the hardness characteristics of concrete and reproduce them. The most disseminated method, that of the steel ball indenter, was used. The relationship between concrete hardness on the one hand and the indenter diameter and test load on the other was established on the basis of earlier ideas on the structure and mechanical resistance features of the material and the possibility was demonstrated of using conventional micro and macro hardness test data for this estimation. The influence of methodological and technological factors in hardness testing was examined.

ChemInform Abstract: HERTZIAN FRACTURE OF VITREOUS CARBON

AbstractDas Bruchverhalten von glasigem Kohlenstoff bei Aufprall von Stahlkugel‐ Prüfkörpern wird mit den Theorien von Hertz verglichen.

Hertzian Fracture of Vitreous Carbon

Hertzian fracture produced by steel ball indenters on vitreous carbon is qualitatively similar to Hertzian fracture of soda‐lime glass. The bulk material obeys Auerbach's law, i.e. the critical fracture load is proportional to the ball radius. However, a surface layer of material, which is denser than the bulk, is stronger and does not obey Auerbach's law. The fracture energy calculated from Auerbach's law and the theory of Frank and Lawn is more than an order of magnitude lower than that measured by conventional methods. Part of this discrepancy arises from the fact that the ring crack is 17% larger than the circle of contact. The fracture surface energy of vitreous carbon as determined by a somewhat empirical application of Auerbach's law is ∼3.5 J/m2. The Hertzian fracture stress of vitreous carbon, like that of soda‐lime glass, approaches the transverse rupture strength (TRS) when large indenters are used.

Effects of Various Errors on the Superficial Rockwell Hardness Reading : 1st Report, Tests Using the Steel Ball Indenter

The superficial Rockwell hardness tester comes into use for quality control of thin metal sheets because of quickness of testing. Therefore the establishment of JIS (Japanese Industrial Standard) on this hardness tester is urgently needed. This report makes clear the effects of errors in the preliminary load W1 kg, the total load W2 kg and the diameter D mm of the steel ball indenter on the superficial Rockwell hardness reading. The extended Meyer's law that has been successfully used for the Rockwell hardness test is again applied to this test although the loads in the latter are smaller than in the former. The deviation of the hardness reading is theoretically analyzed and the following formula is obtained, taking the Meyer's index n as 2.3. For example, ΔHR30T=(100-HR30T)(0.044 9ΔW1-0.033 7ΔW2+0.466ΔD). A good agreement is observed between the calculated values and the experimental ones. In addition, the authors' proposal for establishing a tentative JIS is shown.

Effects of Various Errors on the Superficial Rockwell Hardness Reading: 1st Report In Case of Using the Steel Ball Indenter

Effects of Various Errors on the Superficial Rockwell Hardness Reading: 1st Report In Case of Using the Steel Ball Indenter