| Steel materials are widely used in various fields due to their excellent properties,but the poor corrosion resistance is the main reason restricting their further application.Therefore,It is urgent to enhance the corrosion resistance of steel materials,the current surface modification technology mostly is liquefaction,which has defects such as stomatal inclusion and high dilution rate after solidification.As a solid phase welding technology,friction surfacing can realize the connection of dissimilar materials,modify the material surface and overcome metallurgical defects.it is significant to study and reveal the relationship and mechanism between the process and microstructure,properties to the application of friction surfacing and steel materials.In this paper,the friction of aluminum alloy on the surface of low carbon steel with different rotational feed and welding speeds was selected,record the temperature change,the morphology quality and size of the weld were observed and measured.OM SEM and EDS were used to systematically study the element distribution and composition of materials on both sides of the interface,and judge the formation of intermetallic compounds.Measuring the hardness distribution on both sides of the interface and the bonding strength and corrosion resistance of the surfacing layer.the relationship between the above output variables and various process parameters and the corresponding influence mechanism are discussed.The main research contents and results are as follows:The width and thickness of the surfacing layer decrease with the increase of welding speed,rotational speed and feed speed,which is caused by the influence of the real contact surface.Under all parameters,the microstructure of the steel side is ferrite and pearlite,which is consistent with the microstructure of the substrate before welding.TMAZ grain is elongated and fibrous.The microstructure of aluminum side is fine equiaxed grain and black grain,and it at high welding speed is smaller than that at low welding speed.With the increase of rotational speed,the grain structure grows slightly,and the feed speed has no effect on the grain structure.Four kinds of intermetallic compounds Fe2Al5,Fe Al,Fe Al2,Fe Al3 are found at the bonding interface under different parameters.the thickness of intermetallic compound layer at the bonding interface decreases with the increase of welding speed and increases with the increase of rotational speed and feed speed.The effective heat of formation model combined with diffusion kinetics is proposed to predict and determine the intermetallic compounds formed by Fe-Al,and the results are basically consistent with those measured by EDS analysis.The hardness of materials on both sides of the interface at low welding speed is lower than high welding speed.The hardness tends to be consistent with the increase of feed speed.In addition,the hardness of surfacing layer is higher than consumable base material.It reached 106.62HV when the rotational speed was 950 rpm.The bonding strength of surfacing layer decreases with increasing welding speed.With the increase of feed speed,it shows an upward trend.With the increasing speed,it does not show an obvious trend,The bonding strength of the sample reaches the maximum when the welding speed is 60mm/min.With the increase of welding speed,the corrosion potential moves to the right and the current density moves down.The corrosion resistance of the surfacing layer at high welding speed is higher than at low welding speed.The increase of rotating speed leads to left shift of corrosion potential,up shift of current density and decrease of corrosion resistance.The corrosion resistance of the surface is decreased.At the rotational speed is 950rpm,welding speed is 100mm/min and feed speed is 20mm/min,the corrosion resistance is the best The corrosion morphology of the surface is composed of bright white massive dark gray particles and a large number of fine corrosion holes,and the corrosion product is mainly Al2O3. |
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