The Research Of Plasma Cladding Preparation Fe-Al Intermetallic Compound Coating Perform On The Surface Of Q235Steel

In this paper, The Plasma cladding technology was used to prepare Fe-Alintermetallic compound coating on the face of Q235, metallographic observation,microhardness testing on the cladding layer were carried out, and then themicrostructure and mechanical properties of the Fe-Al intermetallic compound coatingwere studied by means of SEM, XRD analysis.In this paper the preparation of Fe-Al intermetallic cladding layer need to meet thefollowing requirements: no stomatal crack and the obvious flaw, but metallurgical bondafter argon shielded arc remelted to the base metal. metallurgically bonded with thesubstrate would be gained, and must ensure that low dilution rate. So in order to get theclad layers of good quality, the plasma cladding process were investigated as follows:（1）First, the reasonable cladding process was designed by use the orthogonal design,when the prefabricated layer thickness for fixed value2mm, nozzle height10mm. thebest specific process parameters were as follows: Transfer arc current:140A, Transferarc voltage:36V, Arc swing speeds:1200mm min, Ion flow:0.3m³/h, Welding speed:30mm min, Swinging the width:20.5mm electric arc, Protection gas flow:0.8m³/h.（2） The three groups of Fe-Al intermetallic compound coating in different content ofAl were prepared（Al content were10%,20%,30%, and the rest are Fe）, experimentalinvestigation shows that:（a） The composition are Fe₃Al, FeAl, and α-Fe in different Alcontent of cladding layers;（b） The microstructure of cladding layers are bulky columnarexhalation, and the needle separation material appears irregular arrangement, the studyshow that the bulky columnar crystal matrix organization is theα-Fe, needle separation isFe₃Al, as the the content of Al in the cladding layer increase, the cladding layer needleseparation material is increasing, but when Al content was30%, the cladding layer hasbulky needle exhalation, the bulky needle is also for Fe₃Al which proved by XRD EDSanalysis;（c） microhardness testing on the cladding layer of three groups in differentcontent of Al were carried out, the result show that hardness is increase with the increaseof the content of Al.（3） Fe, Al and ferrochrome were used as raw material, three groups of intermetalliccompound coating in different content of Cr were prepared（Cr content is5%,10%,15%,and Fe: Al=7:1）, the research indicated that: when the Cr content is5%, the claddinglayer have particles phase （Fe₃Al） generation, the micro hardness of cladding layerchange little; when the Cr content is10%, the microstructure of cladding layer had notchanged significantly, but the micro hardness of cladding layer has Increased; when the Cr content is15%, the cladding layer have hard phase（Fe,Cr）₇C₃formation, But due touneven distribution of the hard phase, the microhardness curve of cladding layer appearsirregular curve.（4） the plasma cladding process will produce defects just like the stressconcentration, so the annealing processing must use after cladding, in this paper, threegroups of annealing process was used:700℃×2h、800℃×2h、900℃×2h uniformityannealing processing for cladding layer. experimental investigation shows that thehardness have increased significantly after700℃×2h uniform annealing; the hardness ofcladding layer depressed after800℃×2h uniform annealing; when after900℃×2huniform annealing the organization of cladding layer are not evenly distributed, thehardness is decreased obviously.