Search Results

As a fusion welding process, Laser welding has proven to be the most promising method for joining of different materials whether it can be either a similar or dissimilar material category.

Nd: YAG Laser Welding Process (LWP) is the most efficient method commonly used for the joining of different kinds of materials, whether it can be a sheet or plate. LWP in general, uses high power density, frequency and travel speed or feed rate as primary process parameters in order to perform a joining process across the metals. This paper investigates the effect of free vibrational characteristics for Stainless Steel 304 (SS 304) joints which are reinforced with Al2O3 micro particles processed by dual side (welding performed on the top and bottom surface of sheets) Nd: YAG LWP. The inclusion of micro particles was inserted directly across the weld pool region, by fabricating drills with a constant gap between each drilled holes. Totally 12 samples were fabricated with different laser power, travel speed and by keeping the frequency level as constant for all the experiments.

Laser welding process is a most effective and predominant method for joining of steel alloys when compared with other welding processes in practice due to their precise control of laser source across the bonding zone where it is crucial to control in other joining processes. In common the austenitic steels differ from ferritic based on two factors, thermal conductivity and expansion. Here, the selected Nd-YAG laser setup for joining of similar base material stainless steel 316 which is reinforced with and without stellite 6 powders. The experimental investigations (metallurgical survey and wear characteristics) were performed on all the samples. The powders were reinforced in the material directly by performing a drill across the bond line instead of a normal coating process which is in practice, later the powders were stuffed through the holes.

In the present work, fabrication of similar Stainless Steel (SS) 304 joints by Nd-YAG Laser Welding Process (LWP) was done. A novel approach was attempted in this study. Welding was performed on dual sides of the plate (top and bottom) for a better mixture of micro powder particles in the weld pool region to achieve maximum depth of penetration, which is not easily possible in a single-sided LWP. High depth of penetration during fabrication of joints, significantly improved the mixture ratio of molten steel with reinforced micro powder particles. Al2O3 micro powder particles were reinforced in the weld pool region through the drilling process with varying depth ratios, and a moderate gap was maintained between each hole. The effects of Al2O3 on the microstructure and mechanical properties were studied and elaborated. Totally 12 samples were fabricated and joining was performed keeping the frequency as constant and varying laser power, travel speed for all the trials.

Tensile and axial fatigue tests were conducted on shallow cryogenically treated EN19 medium carbon alloy steel to investigate its mechanical behavior. The test samples were conventionally heat treated then oil quenched at room temperature. Followed by the samples were kept for shallow cryogenic treatment to -80°C for 8 hours using liquid nitrogen. Then the samples were tempered in a muffle furnace to relieve the induced residual stresses. Tensile and axial fatigue test were carried out on both treated and non-treated samples to measure its tensile strength and fatigue behavior respectively. Microscopic examination also had done to compare the effect of shallow cryogenic treatment on its microstructure. The results exposed that there is an increase in the tensile strength and reduction in fatigue life of shallow cryogenically treated samples over base metal and improved wear resistance.