This study presents a new mechanical tube cladding process named punch plastic deformation pipe cladding (PPDPC) based on local deformation by pressing a punch into the inner layer of the bimetal tube. To investigate the capability of the process, stainless steel tube (as the inner layer) is bonded to a carbon steel pipe (as the outer layer) to fabricate a bimetal pipe. Shear punch tests were used to evaluate the bond strength between layers. Also, optical microscopy (OM) was employed to investigate the bonding interface.Experimental results showed an excellent bonding at the interface of two layers. Shear punch test results showed that the bonding achieved from this new method is stronger than the conventional thermo-hydraulic cladding method. This process is influenced by several parameters including punch diameters, punch nose radius and the friction coefficient between the punch and cladding tube.The effects of these parameters were evaluated by finite element (FE) analysis. Good bonding, simplicity, lower cost and no change in the microstructure of the main pipe (outer layer) are the major advantages of this process.

Our country is located on an Earthquake Belt.In order to reduce the damages caused as a result of an earthquake, attempts should be made to reduce the dead load of buildings. This research is therefore aimed to study the methods for reducing the dead loads of building cladding. The primary aim is to study the Iranian traditional methods of construction for building cladding, and secondly researching the new methods, technology and the available material for covering of building's facade with light weight material in developed countries, and selecting the most compatible material and techniques suited with the current methods of Iranian building construction.Finally an attempt is made to suggest means and recommendations for reducing the dead load of building cladding.

In this research, the microstructure of Inconel 625 cladded layer on ASTM A575 steel has been investigated. By examining different parameters, the optimal single-pass sample with the least amount of dilution, porosity and fusion and suitable wetting angle was determined. Then cladding process with the optimal parameter was performed. The microstructure of the cladding layer was evaluated from the base metal to the top. Due to different cooling rates, dendritic morphologies were observed at different distances. Also, the cladding layer was free of any cavities, porosity and cracks and its thickness was 0. 9 mm (900 micrometers). The results of (XRD) and (EDS) analyzes indicate thatthe γphase is formed and there is a relatively uniform distribution of elements in the cladding layer. These results also indicate that no change in the chemical composition of the substrate surface was achieved near the interface. The hardness test results also show that the hardness starts from 450 VHN at the top surface and reaches to 135 VHN in the base metal with a gentle slope. This slope of hardness can be attributed to the cooling or heating rates of the substrate.

In this research tungsten silicide powder was successfully produced from tungsten and silicon powders using mechanically activated self-propagating high temperature synthesis and then cladded on St37 substrate by gastungsten arc welding method. X-Ray diffraction analysis showed that the best milling time for activation of elemental powders was 10 h. Microstructure evaluation of coating by scanning electron microscope demonstrated that tungsten silicide mainly dispersed in dendrite phase and inter-dendritic phase rich from Iron. Hardness measurements revealed that the surface hardness of substrate increased from 200 to 850 HV. The wear resistance of substrate was improved by six fold via increasing surface hardness.

The aim of this work was to synthesize TiC reinforced coating on carbon steel via reduction of ilmenite powder. A mixture of ilmenite and graphite was pre-placed on AISI 1020 steel surface. The effect of the addition of excess graphite amounts on the progress of the synthesis of carbide particles was studied. The evolution of phases in different coatings was analyzed via X-ray diffraction and scanning electron microscopy. Then, the initial powder mixtures were mechanically activated for various durations, to accelerate the reactions in the transient melt pool. Finally, the Fe-TiC hard coating was successfully synthesized by carbothermic reduction of ilmenite through laser surface treatment. Moreover, it is proved that combination of mechanical activation with additive laser melting effectively improves the level of ilmenite reduction, besides enhancing the distribution of hard particles and the hardness of the coatings to more than 1300 HV.

Low oxidation resistance of low carbon steel restricts the applications of these materials at elevated temperature. Due to the high corrosion and oxidation resistance of Al base alloys, in this research low carbon steel substrate was subjected to the weld cladding with using Al-rich overlayer. Microstructural studies by using optical and scanning electron microscopes indicated the formation of needle-like Al-rich intermetallic with nearly uniform distribution in the Al clad overlayer. This clad overlayer increased the surface hardness of substrate. Phase analysis by using XRD accompanied with chemical composition studies by EDS analysis revealed that the clad layer was comprised FeAl intermetallic as the matrix with Fe3Al and FeAl3 needle-like intermetallics distributed in the clad layer. Results of oxidation test of samples at 500oC for 10-100hr showed the Al-rich clad improves oxidation resistance of samples significantly. In addition, Al rich overlayer increases surface hardness of substrate to 270 Vickers which is twice of substrate hardness.

In coaxial laser cladding, the quality and property of deposition products are greatly influenced by the powder flow, which is responsible to transport additive materials to the deposition point on a substrate precisely. The metallic powder flow in coaxial laser cladding is simulated by a numerical model based on the gas-solid flow theory. The characteristics of powder concentration distribution between coaxial nozzle and deposition point for a kind of nickel based alloy powder are studied by the proposed model. The relationship between the process parameters and powder flow characteristics, such as focus distance from the nozzle exit and maximum powder concentration, is analyzed to optimize the powder feeding process. In addition, the influence of substrate with different surface shapes on the powder flow is investigated. The results can be used as a guideline for the location of the substrate and the selection of proper processing parameters for coaxial laser cladding.