Present study focuses on the micro-structural and mechanical behavior effect of friction time for similar (AISI 316-AISI 316 and AISI 304-AISI 304) and dissimilar (AISI 304-AISI 316) joint during continuous drive friction welding. The welding carried out with different friction time: 6. 5, 8. 5 and 10 s while kept all other conditions constant. The effect of that time on the strength, structural and behavior of welded metals was investigated by Energy Dispersive Spectroscopy (EDAX), Scanning Electron Microscope (SEM), micro-hardness and tensile test. The obtained results illustrated that the friction time extended was responsible on some harmful mechanical and micro-structural properties of the welded joint. Therefore, increasing in friction time is led to reduce of Ultimate Tensile Strength (UTS), reduce of ductility, increasing in level of micro-hardness and larger HPDZ, that was clearly observed in similar joint (AISI 316-AISI 316 and AISI 304-AISI 304).

The present study describes the effect of friction welding process on mechanical and metallurgical properties of AISI 304 steel. The joints were made by direct drive friction welding (DDFW) machine, while the characteristics of friction welded joints were evaluated by macro-microstructure, microhardness, tensile test with 4 mm and 6 mm effective diameter, and scanning electron microscope (SEM). The results showed severe flash formation at stationary side related to rotating side, highly plastically deformed zone (HPDZ) was revealed at the interface with large dimension of 110 µm. Maximum microhardness values were recorded at welded center and increased from peripheral to central zones. Reducing ratio of ultimate tensile strength (UTS) and ductility for welded joint related to AISI 304 were 86 and 67%, respectively. Tensile fractures occurred adjacent to the interface at thermo-mechanically affected zone (TMAZ). Fracture morphologies by SEM were discovered cleavage features and mostly ductile mode with micro-porosities of different forms and dimensions

The corrosion behavior of Zn/ (AISI304) annealed at different temperatures with flow of nitrogen gas was investigated in the 3. 5%NaCl solution. Crystallography structure of the samples was analyzed using X-ray diffraction (XRD) pattern. The results showed that with increasing annealing temperature, the intensities of oxide and nitride phases were increased. Surface morphology of the samples was studied using atomic force microscope (AFM) before corrosion tests. AFM results showed that by increasing annealing temperature, grains become greater that may be the result of heat accumulation, causing higher rate of diffusion in the sample. Electrochemical Impedance spectroscopy (EIS) and Polarization tests were carried out for corrosion resistance investigation of the produced samples. The corrosion results revealed that highest corrosion resistance was achieved for the sample at the highest annealing temperature. For more in depth analysis, the equivalent circuit of samples was obtained, using the EIS data. Finally, the surface of the corroded samples was observed using scanning electron microscopy (SEM).

The wear behavior AISI 304 stainless steel was investigated after Friction Stir Processing (FSP). FSP was carried out using a WC pin less tool at tool rotation of 560 rpm and tool feed of 50 mm/min. Microstructure analysis was conducted by using optical and scanning electron microscopy evaluations. Wear resistance of the FS processed and base metal specimens were compared using pin-on-disk tests. The results demonstrated that FSP homogenized and refined the grain size of 304 stainless steel. A reduction in grain size throughout the stir zone (26±3) compared to that of the base metal (93±3) was achieved through FSP. These results were confirmed by microhardness evaluations. According to the wear results, wear resistance of 304 base material improved significantly (two orders of magnitude) after FSP. This behavior was attributed to the grain refinement obtained by FSP. According to SEM observations, the abrasive wear was the main mechanism of wear after FSP.

Semi-solid metal forming offers many advantages in comparison with casting and forging. However, due to the high-melting temperature and related difficulties, there is relatively a few experimental data on the semi-solid processing of steels. Therefore, this study is subjected to the microstructure evolution during partial remelting of 304 stainless steel which is pre-deformed in solid state by a severe plastic deformation (SPD) technique. Thermodynamic calculations were carried out by Thermo-Calc software and the results were compared with the experimental observation. In this study, repetitive corrugation and straightening by rolling (RCSR) as a new SPD technique is utilized to induce a great strain in material prior to semi-solid process. Microstructural evolutions were studied in different temperatures and holding times during semi-sold process. The results indicate that finer globular semi-solid microstructure is achieved from 30 cycles RCSR processed specimen after 3 minutes holding at 1425.

Transient liquid phase bonding of UNS S32750 super duplex stainless steel to AISI 304 austenitic stainless steel using BNi-2 interlayer was carried out at 1050 oC for 45 min. Microstructure analyses of the joint were carried out using optical microscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy. Microhardness indentation and shear strength test were performed to assess mechanical behavior of the joint. No eutectic contents was seen at the joint and thus Isothermal solidification was completed at 45 min bonding time. The shear strength of the joint was about 0. 7 of duplex stainless steel shear strength. Froctographic studies revealed that the fracture mode was completely ductile in the case of the joint made at bonding time of 45 min.

Stable ductile crack growth in 3 mm thick AISI 304 stainless steel specimens has been investigated experimentally and numerically. Multi-linear Isotropic Hardening method coupled with the Von-Mises yield criterion was adopted for modeling elasto-plastic behavior of the material. Mode-I CT fracture specimens have been tested to generate experimental load-displacement-crack growth data during stable crack growth. The critical fracture energy (JIc) was then determined using the finite elements results in conjunction with the experimental data. The effect of in-plane constraints on the numerical-experimental JIc calculation was then investigated. The results of finite element solution were used to tailor an exponential CZM model for simulation of mode-I stable crack growth in CT specimens. It is found that the adopted CZM is generally insensitive to the applied constraints to the crack tip stress state and thus it can effectively be used for simulating crack growth in this material.

In this study, the temperature distribution of an AISI 304 stainless steel during gas tungsten arc welding is modeled by using the Goldak's three-dimensional moving heat source. A C++program is developed in order to employ the heat inputs into finite difference thermal simulation of the welded plate. By simulating the temperature distribution and shape of the weld pool, effect of welding parameters such as current and welding speed on the sensitization, weld width and weld depth are evaluated. Results show that the width and depth of weld and sensitized zone increase with rAISIng the current while the sensitization location decreases. The effect of welding speed is vice versa. To verify the simulated results, currents of 160, 200 and 240 A and welding velocity of 2 mm/s are selected for experiments. Good agreement is obtained between the simulated and experimental results.

This work presents the results of a low energy nitrogen ion implantation of AISI 304 type stainless steel (SS) at moderate temperatures of about 500oC. The nitrogen ions are extracted from a Kauffman type ion source at a Energy of 30 keV, and ion current density of 100 mA cm-2. In our study the nitrogen dose of 6×1017, 8×1017 and 1018 ions cm-2, were selected. The X-ray diffraction results show the formation of CrN polycrystalline phase after nitrogen bombardment and a change of crystallinity degree due to the dose effect the image analysis of implanted samples clearly shows significant changes in surface. Corrosion test has shown that corrosion resistance is enhanced by increasing dose.

There is a requirement to find accurate parameters to accomplish precise dimensional accuracy, excellent surface integrity and maximum MRR. This work studies the influence of various cutting parameters on output parameters like Cutting force, Surface roughness, Flatness, and Material removal rate while face milling. A detailed finite element model was developed to simulate the face milling process. The material constitutive behavior is described by Johnson-Cook material model and the damage criteria is established by Johnson-Cook damage model. The result indicate significant effects of all three cutting parameters on MRR and both feed rate and depth of cut have significant effect on cutting force. Also, feed rate has significant effect on PEEQ and none of the parameters have effect on flatness.