钢包壁用铝—镁质浇铸耐火材料

钢包壁用铝—镁质浇铸耐火材料［日］小林正则等１前言近年来，除渣线外，钢包壁（以下简称一般壁）大都采用铝—尖晶石质浇铸耐火材料。由于该浇铸耐火材料使用的是尖晶石熟料，所以其耐蚀性要比单用铝质的高。但是，从本所实际使用结果看，由于渣侵蚀层的剥离（以下简称...

Electrochemical corrosion behaviour of stir zone of friction stir welded dissimilar joints of AA6061 aluminium-AZ31B magnesium alloys

Joining of dissimilar metals will offer many advantages in transportation sectors such as fuel consumption,weightreduction and emission reduction.However,joining of aluminium(Al)alloys with magnesium(Mg)alloys by fusion welding processis very complicated.Friction stir welding(FSW)is a feasible method to join these two dissimilar alloys.Mixing these two metalstogether in stir zone(SZ)leads to poor corrosion resistance.In this investigation,an attempt has been made to understand thecorrosion resistance of SZ of FSWed dissimilar joints of AA6061Al alloy and AZ31B Mg alloy.Potentiodynamic polarization testwas conducted by varying chloride ion concentration,pH value of the NaCl solution and exposure time.The corroded surfaces wereanalyzed using optical microscopy,scanning electron microscopy and XRD techniques.Of these three factors investigated,exposuretime is found to be the most significant factor to influence the corrosion behaviour of SZ of friction stir welded dissimilar joints ofAl/Mg alloys.

5A06-O aluminium−magnesium alloy sheet warm hydroforming and optimization of process parameters

The uniaxial tensile test of the 5A06-O aluminium−magnesium(Al−Mg)alloy sheet was performed in the temperature range of 20−300℃ to obtain the true stress−true strain curves at different temperatures and strain rates.The constitutive model of 5A06-O Al−Mg alloy sheet with the temperature range from 150 to 300℃ was established.Based on the test results,a unique finite element simulation platform for warm hydroforming of 5A06-O Al−Mg alloy was set up using the general finite element software MSC.Marc to simulate warm hydroforming of classic specimen,and a coupled thermo-mechanical finite element model for warm hydroforming of cylindrical cup was built up.Combined with the experiment,the influence of the temperature field distribution and loading conditions on the sheet formability was studied.The results show that the non-isothermal temperature distribution conditions can significantly improve the forming performance of the material.As the temperature increases,the impact of the punching speed on the forming becomes particularly obvious;the optimal values of the fluid pressure and blank holder force required for forming are reduced.

Assessment of solidification characteristics of carbon-inoculated Mg-3%Al melt by thermal analysis

The Mg-3%Al melt was inoculated by carbon with different holding time.The effect of holding time on grain refining efficiency was evaluated.The solidification characteristics of the carbon-inoculated Mg-3%Al melt with different holding time were assessed by computer-aided cooling curve analysis.The results showed that Mg-3%Al alloy could be effectively refined by carbon inoculation.Slight fading phenomenon occurred with increasing the holding time to 60 min.Carbon inoculation could significantly influence the shape of cooling curves of Mg-3%Al melt.The nucleation starting and minimum temperatures increased.The recalescence undercooling and duration decreased to almost zero after carbon inoculation.The grain refining efficiency of carbon inoculation could be assessed by the shape of the cooling curve and solidification characteristic parameters including nucleation starting and minimum temperatures,recalescence undercooling and duration.

Effect of Surface Treatment on Bonding Strength of Aluminum-Magnesium Hot-Rolled Composite Plate

The effect of different surface treatments on the bonding strength of composite plates was investigated under the conditions of 400℃ and reduction ratio of 45%.Results show that the wire brush grinding treatment can only eliminate the oxide film on the plate surface,but it can hardly produce a hard layer on the plate surface.The bonding effect depends on the element diffusion promoted by the close contact between the metals on both sides of the interface.After anodic oxidation,there is a hard layer on the metal surface,and the hard layer broken during the rolling process forms a mechanical occlusion at the bonding interface.However,the hard layer cannot form an effective combination with the metal at the interface,and the bonding can only occur in the fresh metal bonding area at the crack of the hard layer.The acid-alkali washing treatment can completely remove the hard layer on the surface of both alloys without increasing the surface roughness of the plate,and the metal on both sides of the interface is more closely bonded during the rolling process.The optimal bonding strength can be obtained by surface treatment of acid-alkali washing for the aluminum-magnesium hot-rolled bonding.