Ugur Caligulu

The Effect of Welding Speed on the Laser Welding of AISI 430 Ferritic Stainless—AISI 1010 Low-Carbon Steel

Abstract In this study, the effect of welding speed on the laser welding of AISI 430 ferritic stainless steel with AISI 1010 low-carbon steels was investigated. Laser welding experiments, were carried out under argon atmosphere, 2000 W constant welding power and 100, 200, 300 cm/min welding speeds. The microstructures of the welded joints were examined by optical microscopy and SEM analysis. The tensile strength of the welded joints was measured. The result of all observations, tests and measurements indicated that the best properties were observed at the specimens welded at 100 cm/min welding speed.

Wear Properties of Fe-Cr-C and B4C Powder Coating on AISI 316 Stainless Steel Analyzed by the Taguchi Method

Abstract In this study, the plasma arc welded cladding of FeCrC and B4C powder mixtures alloyed with 70 wt.- % Cr on the surface of AISI 316 stainless steel was investigated. Application of the Taguchi method revealed respective effects on the abrasive wear resistance of the cladding layer on the stainless steel. The abrasive wear behaviour of the AISI 316 stainless steel surfaces coated with Fe-Cr-C and with 10 wt.-%, 15 wt.-%, 20 wt.-%, and 25 wt.-% B4C was investigated by using four loads and four distances for the 220 mesh SiC abrasive. Results were analyzed by variance analysis using ANOVA, and effects of parameters on the wear rate were determined as percentage rate. Furthermore, the error ratio was statistically evaluated. The experimental results were analyzed by the respective analysis of means and variance which is discussed in detail.

Optimization of Tensile Strength of Friction Welded AISI 1040 and AISI 304L Steels According to Statistics Analysis (ANOVA)

Abstract Materials difficult to weld by fusion welding processes can be successfully welded by friction welding. The strength of the friction welded joints is extremely affected by process parameters (rotation speed, friction time, friction pressure, forging time, and forging pressure). In this study, statistical values of tensile strength were investigated in terms of rotation speed, friction time, and friction pressure on the strength behaviours of friction welded AISI 1040 and AISI 304L alloys. Then, the tensile test results were analyzed by analysis of variance (ANOVA) with a confidence level of 95 % to find out whether a statistically significant difference occurs. As a result of this study, the maximum tensile strength is very close, which that of AISI 1040 parent metal of 637 MPa to could be obtained for the joints fabricated under the welding conditions of rotation speed of 1700 rpm, friction pressure of 50 MPa, forging pressure of 100 MPa, friction time of 4 s, and forging time of 2 s. Rotation speed, friction time, and friction pressure on the friction welding of AISI 1040 and AISI 304L alloys were statistically significant regarding tensile strength test values.

X-Ray Radiography of Ti6Al4V Welded by Plasma Tungsten Arc (PTA) Welding

Abstract In this study, X-ray radiographic tests of Ti6Al4V alloys welded by plasma tungsten arc welding (PTA) were investigated. PTA welding experiments were carried out under argon shielding gas atmosphere, at 1400–1600 W and 1800 W welding powers as well as 1 m/min, 0.75 m/min, and 0.50 m/min welding speeds. After this process, radiography of the welded joints was performed by X-ray diffraction. The result of the radiographic tests indicated that by increasing welding power the widths of deep penetration increased in all specimens. On the contrary, increasing welding speeds decreases the widths deep penetration. The best properties of Ti6Al4V joints were observed for specimens welded at 1800 W welding power and at 0.50 m/min welding speed.

Interface characterization of friction welded low carbon steel and copper alloys

Abstract In this study, the interface characterization of friction welded AISI 1010 low carbon steel and copper alloys was investigated. The friction welding tests were performed by using a direct drive type friction welding machine. After friction welding, interface regions of the welded specimens were examined by optical microscopy, SEM-EDS, and X-ray analysis to determine the microstructural changes. Microhardness and tensile tests were conducted to determine mechanical properties of the welded specimens. The experimental results indicated that AISI 1010 low carbon steel could be joined to copper using the friction welding technique for achieving a weld with sufficient strength. Tensile strength values also confirmed this result and intermetallic phases did not occur at the interface.

Artificial Neural Network (ANN) Approach to Hardness Prediction of Aged Aluminium 2024 and 6063 Alloys

Abstract In this study, the effect of aging heat treatment on the hardness of AA 2024 and AA 6063 aluminum alloys was investigated by experimental and an Artificial Neural Network (ANN). AA 2024 and AA 6063 aluminum alloys were solution treated at two different temperatures of 490° C and 520° C. Then both samples were cooled to room temperature. After this process, the samples were aged at three different temperatures (140° C, 180° C, 220° C) for ten different periods of time (2, 4, 6, 8, 10, 12, 14, 16, 18, and 20 h.). The experimental results were trained in an ANNs program, and the results were compared with experimental values. It is observed that the experimental results coincided with the ANNs results.

Functional ANOVA investigation of the effects of friction welding parameters on the joint characteristics of aluminum based MMC to AISI 304 stainless steel

Abstract This study investigates the applicability of joining an aluminum matrix composite, reinforced with 5, 10, and 15 wt.-% of SiCp particles, to AISI 304 austenitic stainless steel by using friction welding technique. In this study, optical and electron microscopes, lap shear strength test, and microhardness measurements were used to assess the quality of bonding of Al-Cu-SiCp and AISI 304 austenitic stainless steel joints performed by using friction welding. The strength of the friction welded joints was significantly affected by process parameters (rotation speed, friction time, friction pressure, forging time and forging pressure). Additionally, lap shear and axial shortening test results were analyzed by using analysis of variance (ANOVA) with a confidence level of 95 % to find out presence of a statistically significant difference.

Interface characterization of CO2 laser welded austenitic stainless steel and low carbon steel couple

Purpose – The purpose of this paper is to investigate interface characterization of CO2 laser welded AISI 304 austenitic stainless steel and AISI 1010 low carbon steel couple. Laser welding experiments were carried under argon and helium atmospheres at 2000, 2250 and 2500 W heat inputs and 200‐300 cm/min welding speeds.Design/methodology/approach – The microstructures of the welded joints and the heat affected zones (HAZ) were examined by optical microscopy, SEM, EDS and X‐Ray analysis. The tensile strength of the welded joints was measured.Findings – The result of this study indicated that the width of welding zone and HAZ became much thinner depending on the increased welding speed. On the other hand, this width widened depending on the increased heat input. Tensile strength values also confirmed this result. The best properties were observed at the specimens welded under helium atmosphere, at 2500 W heat input and at 200 cm/min welding speed.Originality/value – There are many reports which deal with th...

Radiographic inspection of AISI 420 steel friction welds

Abstract In this study, X-ray radiographic tests of AISI 420 steel welded by friction welding were studied. During the welding process, three different rotations, 700, 1000 and 1300, were employed while the other parameters such as friction pressure, friction time, upsetting-pressure and upsetting-duration were unchanged. After the completion of welding process, the welded joints were subjected to radiographic tests by X-raydiffraction. The result of the radiographic tests indicates that by increasing rotation speed the amount of flash and joining properties/performance increases in all samples. The best properties of the AISI 420 martensitic stainless steel joints were observed in samples welded at a rotation speed of 1300 (rpm). It has been determined that in harmony with the definition of welding defects and respective radiographic images, lack of fusion is the most common welding defect.

Yüksek Hızlı Oksi Yakıt ile Üretilen WCCo-Mo Esaslı Kaplamaların Mikroyapı Karakterizasyonu

Bu calisma, yuksek hizli oksi yakit (HVOF) isil puskurtme yontemi ile SAE 4140 celigi uzerinde uretilen WCCo-Mo kompozit kaplamalarin mikroyapisal ozelliklerini arastirmak icin yapilmistir. Bu amac icin WCCo tozlarina ilave edilen Mo miktari % ag. 10, 20, 30 ve 40 olarak degistirilmistir. Kaplamalar, faz bilesimi, mikroyapi ve sertlik ozellikleri acisindan karsilastirilmistir. Kaplama tabakalarinin faz bilesimi ve mikroyapisi X-isini difraktogrami (XRD) ve taramali elektron mikroskobu (SEM) ile incelenmistir. XRD sonuclari, WCCo-Mo kaplama tabakasinin WC, W2C, Co3W3C, Mo2C, MoO2, Mo ve Co fazlardan olustugunu gostermistir. Kaplamalarin sertligi Mo artisi ile artmistir. The present study has been carried out in order to investigate the microstructural properties of WCCo-Mo composite coatings deposited onto a SAE 4140 steel substrate by high velocity oxygen fuel (HVOF) thermal spray. For this purpose, the Mo quantity added to the WCCo was changed as 10, 20, 30 and 40 wt. % percents. The coatings are compared in terms of their phase composition, microstructure and hardness. Phase compound and microstructure of coating layers were examined using X-ray diffractometer (XRD) and scanning electron microscope (SEM). XRD results showed that WCCo-Mo composite coatings were mainly composed of WC, W2C, Co3W3C, Mo2C, MoO2, Mo and Co phases. The average hardness of the coatings increased with increasing Mo content. Anahtar kelimeler: Mo, WCCo, HVOF, Mikroyapi, Sertlik