جستجوی مقالات مرتبط با کلیدواژه « آخال » در نشریات گروه « مکانیک »

In submerged-arc welding, flux is produced through bonding so that alloying element can be added to Weld Metal. In this method, mineral ingredients and alloying elements are milled and mixed with glue in appropriate proportions. Once the drying of the pellets is complete in air, they are baked at 350 degree centigrade and broken up by using a sieve to attain the desired particle size (0.3-1 mm). The various content of Cr, Mo and Cr-Mo was added to bonded flux. Addition of alloying elements was done through flux and slag-weld metal reactions. Mechanical properties were studied by means of Longitudinal Tensile, Hardness and Charpy V-notch tests. Microstructure was studied by means of Optical and Scanning Electron Microscope. The addition of 0.4 wt. % Mo increased the volume fraction of Acicular Ferrite (AF) to 87%. The Ultimate Tensile Strength (UTS) increased by 20% and Impact Toughness (IT) decreased by 25%. Cr affected AF content less than Mo. The addition of 0.4 wt. % Cr increased the volume fraction of AF to 57%. The UTS almost did not change and IT decreased by 35%. Further increase in Cr content led to increase of Ferrite with Second Alloyed phase that strongly impaired IT (60%). The highest proportion of AF (95%) obtained in 0.28 wt. %Cr and 0.35 wt. % Mo. In this specimen UTS increased by 20% (100 Mpa) and Impact Toughness was decreased by 15% (20 j).

Maraging Steels are a group of steels having high strength and toughness. Presence of inclusions in these steels are harmful for their strength and toughness. Also، there are some active elements within these steels. Therefore، application of advanced melting، refining and casting processes such as vacuum processes are used greatly in production of maraging steels. In this research two C300 maraging steel with 0. 65 and 1 wt% Ti were casted firstly in VIM furnace. Then samples subjected to VAR process in order to study the effects of this process on mechanical properties، inclusions content and gas atoms within the steel. The results show that during VAR process of the bars casted in VIM furnace، the total N and O gases reduced to 14%، ductility and resistane to impact increased up to 30% and 47%، respectively. Comparison of these two steels that produced by VIM+VAR showed that increasing of titanium from 0. 65 to 1 wt% causes marginal increasing in strength and hardness and marginal decreasing in ductility and resistance to impact of steel.