Cevdet Meriç

The effects of conventional heat treatment and boronizing on abrasive wear and corrosion of SAE 1010, SAE 1040, D2 and 304 steels

Abstract The effects of conventional heat treatment and boronizing on SAE 1010 and SAE 1040 structural steels, D2 tool steel, and 304 stainless steel were investigated. During this investigation, layer thicknesses, corrosion and wear strength were examined by applying carburisation, nitriding, transformation hardening and boronizing to the specimens. Abrasive wear tests were carried out in a wear cup model device. Sand of 1 mm diameter was used and the test duration was 40 hours with a velocity 0.157 m/s. Corrosion tests were undertaken in a 10% H 2 SO 4 solution at a temperature of 56°C. Through metallographic analyses, hard layer thicknesses and Vickers hardness values were determined for each hardening treatment.

Investigation of the effect on boride layer of powder particle size used in boronizing with solid boron-yielding substances

In this study, the effect of particle size of powder used in the boronizing process with solid boron-yielding substances on the boride layer was investigated. Hot-shaped AISI 1020, AISI 1030, AISI 1040, and AISI 1050 structural steels were used as the base materials. EKabor HM powder was used as the boronizing agent, and was classified into four groups according to particle size. The boronizing process was carried out with each group at 900°C for 2, 3, 4, and 5 h. The microstructure, microhardness, and layer thickness of the boronized materials were investigated.

Investigation of the effect of boronizing on cast irons

Gray iron, ductile iron and compacted graphite iron were boronized with solid boron-yielding substances by box-boronizing method. Commercial EKabor® 3 powder is used as the boronizing agent and the treatments are carried out at 850, 900 and 950°C for 2, 3, 4, 5 and 6 h. Thickness and microhardness of the boride layer, and the microstructure of the boronized specimens are reported.

Physical and mechanical properties of cast under vacuum aluminum alloy 2024 containing lithium additions

Abstract Physical and mechanical properties of aluminum alloy 2024 containing lithium additions were investigated. Lithim (2, 3, and 4 wt%) was added to the alloy of 2024. Melting was carried out in an induction furnace under argon gas protection; casting was performed under vacuum. The cast material was hot extruded to produce tension test rods. To obtain the maximum strength and hardness, the specimens were solution heat treated at 495°C, then quenched in water at room temperature. They were then aged. For the purposes of comparison, some of the specimens were melted under argon gases, but casting was done without vacuum. All the specimens were subjected to tension and hardness tests. In this study, an increase of 6% in the modulus of elasticity and 3% decrease in the density were obtained for 1% lithium added to the alloy. The mechanical properties of the alloys cast under vacuum were found to be better than those cast without vacuum. Whatever the lithium percent in the alloys, all the mechanical properties reached their maximum level in 1 week of natural aging; for artificial aging, maximum levels were reached at 120°C in 24 h, at 160°C in 16 h, at 190°C in 12 h, and 200°C in 2 h. By increasing the lithium percent, the specific elastic modulus (E/ρ) of the alloy increased rapidly but the specific strength (σ/ρ) remained constant. Thus, aluminum lithium alloys that are difficult to manufacture by known methods can be manufactured safely by the vacuum metallurgy method.

Experimental microhardness for AA 1030, Cu, CuSn7, CuZn30 and 6114 alloys and a correlation with the Hall-Petch relation

In this experimental study, the strip-formed specimens made from aluminum alloy 1030, pure Cu, CuSn7, CuZn30, and low-carbon steel 6114 were cold worked to different ratios. To determine the microhardness values of the materials, microhardness tests were applied. The grain sizes of the materials were determined by the Heyn method, using a metal microscope. The hardness of materials, H, is dependent on the grain diameter, d, in a way similar to the yield stress in the Hall–Petch relation H = H0 + KHd−1/2, where H0 and KH are constants. The microhardness of the materials was found, with reasonable accuracy, to vary with grain size according to the Hall–Petch equation.

Determination of tribological properties at CuSn10 alloy journal bearings by experimental and means of artificial neural networks method

Purpose – It is important to know the friction coefficient and wear loss for determination of tribological conditions at journal bearings. Tribological events that influence wear and its variations affect experimental results. The purpose of this paper is to determine friction coefficient and wear loss at CuSn10 alloy radial bearings by a new approach. In experiments, effects of bearings have been examined at dry and lubricated conditions and at different loads and velocities.Design/methodology/approach – In this study, friction coefficient and wear losses of journal and bearing have been determined by a new approach with a radial journal bearing test rig and artificial neural networks (ANNs) method. The ANN typifies a learning technique that enables the hidden input‐output relationship to be mapped accurately. Bronze‐based materials have been used as bearing material. Effects of friction coefficient and wear losses have been examined at same load and velocity and at dry and lubricated conditions.Findings...

Sürtünme Kaynağı ile Birleştirilmiş Farklı Malzemelerin Kaynak Bölgesinin İncelenmesi

Surtunme kaynagi otomotiv, makine, havacilik ve uzay endustrilerinde yaygin bir sekilde kullanilmaktadir. Diger kaynak tekniklerinin yetersiz kaldigi ozellikle silindirik parcalarin kaynaklarinda basarili bir sekilde uygulanmaktadir. Aluminyum–celik, aluminyum–bakir, celik–seramik, aluminyum–seramik gibi malzemeler, bu yontemle birlestirilebilir. Bu calismada, piyasadan temin edilen AISI 304–SAE 1040; AISI 304–SAE 1020; ETIAL F1–SAE 1040; SAE 1040–SAE 1020; AISI 304–ETIAL F1; ETIAL F1-BS EN Cu-OF malzeme ciftlerinin surtunme kaynagi gerceklestirilmistir. Yapilan bu kaynakli birlestirmelerin kaynak bolgesinin metalurjik ve mekanik ozeliklerinden sertlik belirlenmistir. Mikrosertlik degerlerindeki degisimler ve icyapilar da incelenmistir

Al-Sic Kompozitinin Lazer Kaynağı ile Birleştirilmesi

Son y llarda havac l k endustrisinde aluminyum kompozitlerine hafif olmalar ndan dolay onem verilmektedir. Metal matriksli kompozitlerin kayna gozeneklilik ve takviye elemanlar ndan dolay zordur. Bu malzemelerin geleneksel kaynak yontemleriyle kaynak edilmesinin zorlu u nedeniyle lazer kayna ile cal malar ba lam t r. Lazer kayna ticari kaynak yontemlerine gore ce itli avantajlara sahiptir. Bu cal man n amac Al-SiC kompozitlerinin lazer ile kaynak edilebilirli ini ara t rarak, kaynak icin uygun parametreleri tespit etmektir. Sonucta, toz metalurjisi yontemiyle uretilmi Al-SiC kompozitlerinin, farkl artlarda lazer kayna ile birle tirilmesi sonucu mikroyap ve cekme deneyi sonuclar verilmi tir

Effect of Material Nonlinearity on Symmetric Aluminum Metal–Matrix Laminated Composite Beams Under a Bending Moment

In this study, an elastic–plastic stress analysis is carried out on symmetric laminated composite beams subjected to a bending moment. The composite beam is to be strain hardening. The Tsai–Hill theory is used as a yield criterion in the solution. The Bernoulli and Euler hypotheses are assumed to be valid. The beam lay-up sequences are chosen as [90°/0°] s , [30°/−30°] s , [45°/−45°] s , and [60°/−60] s . The bending moment starting plastic yielding is found to be highest for [30°/−30°] s orientation. σ x residual stress component is found to be highest at the upper and lower surfaces. However σ x residual stress component becomes the highest at the elastic and plastic boundary for further expansion of the plastic region. The transverse displacement is obtained at the free end, numerically.