In this study, the electric resistance spot welding process has been applied to dual-phase (DP 600 type) steel sheets. Spot welding parameters, namely, electrode form, electrode material, and electrode force were stayed constant, and welding current and welding time have been changed to detect the optimum welding parameters for maximum joint strength. The sample welded joints have been carried out as 1.0 mm-1.0 mm, 1.2 mm-1.2 mm, and 1.0 mm-1.2 mm in three different thickness combinations in 4, 5, 6, 7, and 8 kA welding currents and 5, 10, 15, 20, and 25 cycles welding times. The strengths of the joints under uniaxial tensile-shear and tensile-peel loading have been studied and compared with the conventional spot welds of maximum joint strength for similar thickness steel sheets. The microstructure and hardness of spot welded joint samples have also been studied andrecommendations were given to users showing the optimum welding parameters.

Bolt production with a grade of 10.9 class quality made from AISI4140 material with a low thread rolling index is usually implemented in accordance with the thread rolling method (cold forming) in industrial applications. In this method, the effects of die revolutions and multiple passes are unknown in the thread forming process as the devices are usually operated with respect to geometrical dimensions but not the mechanical properties and microstructures of the material. In the literature there are few studies on microstructures of low-carbon steel having a higher thread rolling index in bolt production. This study experimentally examined the effects of the processing parameters on the mechanical properties and microstructures. Parameters such as forming speed and single or multi-pass influences were considered in the production of M12 × 1.75 and M20 × 2.5 fasteners widely used in industrial applications. The experiments identified the behavior of the mechanical properties, microstructures and micro-hardness of the AISI4140 material at two forming speeds (rpm) and three passes in the thread rolling process. Thus, significantly sensible outcomes as a function of processing parameters were obtained considering the thread strength viewpoints.

Bolt production with a grade of 10.9 class quality made from AISI4140 material with a low thread rolling index is usually implemented in accordance with the thread rolling method (cold forming) in industrial applications. In this method, the effects of die revolutions and multiple passes are unknown in the thread forming process as the devices are usually operated with respect to geometrical dimensions but not the mechanical properties and microstructures of the material. In the literature there are few studies on microstructures of low-carbon steel having a higher thread rolling index in bolt production. This study experimentally examined the effects of the processing parameters on the mechanical properties and microstructures. Parameters such as forming speed and single or multi-pass influences were considered in the production of M12 × 1.75 and M20 × 2.5 fasteners widely used in industrial applications. The experiments identified the behavior of the mechanical properties, microstructures and micro-hardness of the AISI4140 material at two forming speeds (rpm) and three passes in the thread rolling process. Thus, significantly sensible outcomes as a function of processing parameters were obtained considering the thread strength viewpoints.

This study was aimed to produce and test dental implants made out of biocompatible commercial pure titanium (Grade 4) material with improved mechanical strength. The implant samples were designed and manufactured in real sizes using both machining and thread-rolling (TR) processes. This study is also discovering the benefits of cold forming (TR) versus machining processes in terms of increased efficient strength and reduced costs. To produce the samples using the TR method, a suitable TR processing bench including a pair of reverse threaded flat dies and relevant jigs and fixtures were designed and manufactured. The produced implant samples were tested with static and dynamic loads considering the requirements of the ISO14801:2016 standards. The obtained results were compared in terms of mechanical strength and fatigue life. Their microscopic structures and micro-hardnesses were examined to realize the effects of the manufacturing processes. In addition, the effects of hardness, surface roughness, and residual stresses on both mechanical strength and fatigue life of the implants were also evaluated. Therefore, the obtained results showed that the TR process is extremely effective to improve the implant strength and fatigue life.

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