Contrasting the mechanical and metallurgical properties of laser welded and gas tungsten arc welded S500MC steel

S500MC steel is a grade of high-strength low-alloy steel (HSLA) which is widely used in the automotive industry and for agricultural machinery and equipment. Considering properties of this alloy, selection of the welding process and parameters becomes essential to ensure that HSLA assemblies meet specific service requirements. In this work, mechanical and metallurgical properties of S500MC steel produced by autogenous laser beam welding (LBW) and automatic gas tungsten arc welding (GTAW) were compared. Tensile testing, metallography, hardness testing, and fractographic analysis were performed on the welded specimens, revealing that the heat input by these welding processes caused significant microstructural changes within the joints. In LBW samples, the heat input about 10 times lower than that in GTAW produced a finer microstructure, narrower fusion zone width, and smaller heat-affected zone. All fractures of the GTAW specimens occurred in the base metal, while all fractures of the LBW specimens occurred in the weld zone, both regardless of the heat input. GTAW joints exhibited higher mechanical properties (even higher than those obtained in the base metal) as compared to LBW joints

Investigating laboratory parameters of the resistance of different mixtures of soil – lime – fume using the curing and administrative method

Soils treatment is affected by various factors such as density, moisture content and mineral composition of soil and different percentages of materials in soil. Lime soil as a suitable and inexpensive material has been used for decades to stabilize in civil engineering projects; however, the effect of adding fume and curing temperature on strength and stability parameters of the mixture seldom been studied. In this study, soil and water has been studied from Dokhtar Borji in Hosseinieh city in Iran. Based on a laboratory study, we dealt with evaluating the physical and mechanical properties of soils and chemical properties of soil and water. The cylindrical samples of different mixtures of soil- lime- fume were modified using the AASHTO method and compressive strength testing of 7-, 14- and 28-day samples were conducted according to ASTM standards at 27 °C. Analysis was conducted in SAS (Statistical Analysis System) software. Results indicated that the increase in average compressive strength from 7 to 14 and from 14 to 28 days were 62 and 53.57%, respectively. Therefore, by increasing the number of curing days from 7 to 14, the percentage of the compressive strength is at its highest. The study also provided a linear regression equation that determines compressive strength with an accuracy of 95.1%