E. Ilhan

The Effect Of Nugget Sizes On Mechanical Properties In Resistance Spot Welding Of SPA-C Atmospheric Corrosion Resistant Steel Sheets Used In Rail Vehicles*

Abstract This publication presents an experimental study on the resistance spot welding of SPA-C steel sheets used in side wall and roof application of rail vehicles. SPA-C atmospheric corrosion resistant steel sheets with a thickness of 2.3 mm were joined by using resistance spot welding as lap joint. A timer and current controlled resistance spot welding machine with 120 kVA capacity and a pneumatic application mechanism with a single lever were used to join the specimens. Welding periods were chosen as 5, 10, 15, 20, 25 and 30 cycles (1 cycle = 0.02 s) and also welding currents were increased from 6 kA up to 14 kA by rising in steps of 0.5 kA. The electrode force was kept constant at 6 kN. The welding joints obtained were exposed to tensile peel and tensile shear tests and their nugget sizes were calculated by results of optical microscopy measurements. The effect of nugget sizes on tensile peel strength and tensile shear strength was researched by using related diagrams and the optimum welding currents and times were advised.

An investigation of the factors affecting the design of drum dryers

This work is concerned with the investigation of the factors affecting the design of drum dryers. In the experimental procedure, AISI 4140 was used as a drum material, while HSS was used for a scraping knife. In order to increase the hardness and wear resistance, the drum was coated with the harder chromium, and then it was ground for the improvement of the surface quality. The micro-hardness of the drum was increased more than 10 times of the original drum; as a result better wear resistance was obtained. In addition, electrical measurements were done via a digital ohmmeter to calculate the real contact area between the drum and the scraping knife and the resistance was decreased with the increment of load. Finally, the contact between the couple (drum and knife) was increased with the increment of temperature.

SAC METAL ŞEKİLLENDİRMEDE MUKAVEMET ARTTIRMA VE SONLU ELEMANLAR ANALİZLERİNİN DİNAMİK TESTLER İLE KARŞILAŞTIRILMASI

Bu calismada, beyaz esya sanayide yatay eksendeki kapaklarin acilip kapanmasini ve istenen seviyelerde dengede durmalarini saglayan yayli bir mentese mekanizmasi ele alinmistir. Mentesenin montajlanacak oldugu urunun geometrik sinirlari, calisma sartlari ve calisma araliklari tanimlidir. Menteseyi olusturan her bir parca icin detayli cizimler “SolidWorks” yazilimi yardimi ile yapilmis, 3d model olusturulmustur. Calisma esnasinda mentese mekanizmasi acma kapama omur test cihazi ile test edilmis ve deformasyona ugrayan parcalar belirlenmistir. Deformasyona ugrayan parcalarin sonlu elemanlar analizleri “SolidWorks Simulation” ile yapilmis, test sonuclarinin analiz verileri ortustugu gozlenmistir. Deformasyona ugrayan parca uzerinde geometrik iyilestirme yapilarak sonlu elemanlar analizleri ile yapilan iyilestirmenin sayisal karsiligi degerlendirilmis, alinan sonuclar laboratuvar testleri ile karsilastirmali olarak incelenmistir.

Microstructural Investigation of SPA-C Steel Sheets Used in Railway Vehicles in Resistance Spot Welding

This paper presents an experimental study on resistance spot welding of SPA-C steel sheets used in side wall and roof in rail vehicles. SPA-C steel sheets having 2.3 mm thicknesses were joined by using resistance spot welding as lap joint. A timer and current controlled resistance spot welding machine having 120 kVA capacity and a pneumatic application mechanism with a single lever was used to prepare the specimens. Welding periods were chosen as 5, 10, 15, 20, 25 and 30 cycles and also welding currents were increased from 6 kA up to 14 kA by rise of 0.5 kA. The electrode force was kept constant at 6 kN. The micro and macro-structures of prepared welding specimens were investigated by means of an optical microscope and scanning electron microscope (SEM) in order to see the joinability of SPA-C steel sheets by resistance spot welding.