Surface modification of low carbon steel substrate by Al-rich clad layer applied by GTAW

Low cost and good properties of low carbon steels introduce this material suitable for a wide variety of industrial applications. Developing overlays cladding with desired properties on the surface of these steels seems to be the best way to increase the corrosion and wear resistances of low carbon steels. In the present research, the solidification sequence and the characteristics of Al base weld cladding on AISI 1006 substrate were studied. The optical and scanning electron microscopic studies revealed the formation of acicular-like intermetallic compounds in the clad overlayer. XRD phase analysis illustrated that the clad layer consisted of ordered Fe₃Al and FeAl₃ intermetallic compounds in the FeAl intermetallic matrix. The formation of these intermetallics in the Fe–Al overlayer cladding resulted in a significant improvement of hardness and oxidation resistance of Fe–Al cladded samples.     

Improvement of Structural and Mechanical Properties of Al-1100 Alloy via Friction Stir Processing

In the present study, the relationship between structural and mechanical properties of friction stir processed Al-1100 alloy and process parameters (tool rotation rate: ω and traverse speed: ν) was studied to get an better understanding and optimizing the friction stir processing (FSP) condition of this alloy. Microstructural studies revealed that increasing of ω up to 720 rpm resulted in grain refinement in the stirred zone (SZ), but higher increasing of ω caused grain growth in this zone. These variations of SZ grain size illustrated that the prevailing factor that determined the SZ grain size was plastic deformation at first and thereafter, peak temperature in the SZ. Mechanical properties investigations were in accordance with microstructural findings and illustrated that optimized FSP condition for Al-1100 alloy was 720 rpm and 20 mm/min. Optimized FSP condition resulted in a significant improvement of tensile strength and elongation up to 22 and 8% of those of base metal, respectively.     

Correlation Between Potentiodynamic Polarization Behaviors of Transient Liquid Phase Bonded 2205 Duplex Stainless Steel and the Bonding Constituents

In order to precisely evaluate the contribution of each bonding constituent to the pitting corrosion resistance of transient liquid phase (TLP) bonded 2205 duplex stainless steel (DSS), we have undertaken potentiodynamic polarization (PDP) and microstructural analytic measurements all across the TLP bonded area. The PDP results show that the pitting corrosion resistance of TLP bonded specimens is significantly affected by the presence of certain bonding constituents across the TLP bonded area. Electron microscopy analysis indicates that the formation of complex (Fe,Ni,Cr,Mo)₃P phosphide in the bonding zone (BZ) before the completion of isothermal solidification (IS) as well as the formation of P-rich sigma phase in the diffusion-affected zone (DAZ) following the completion of the IS provides the most preferential sites for the occurrence of pitting corrosion. The PDP results also confirm that the pitting potentials (E_pit) of the TLP bonded specimen before and after IS completion are, respectively, closer to the E_pit of the BZ and the E_pit of the DAZ rather than to those of other TLP BZs.