Effect Of Heat Treatment And Interlayer On Microstructure And Properties Of C276/Q235B Vacuum Rolled Composite Plate

C276/Q235B composite plate combines the excellent corrosion resistance and oxidation resistance of C276 alloy with the excellent molding,thermal conductivity and high toughness of Q235B,and reducces the use of expensive material C276,greatly reducing the cost of engineering,has a wide application prospect.However,at present,the processing technology of C276/Q235B composite plate is still in the stage of exploration and development,and there are few relevant studies.In actual production,there are also many problems,such as poor performance coordination between C276 and Q235B,low interface bonding strength and so on.In this thesis,aiming at the problems existing in C276/Q235B composite plate,based on the actual production process,this paper studies the effects of post rolling heat treatment（solid solution treatment,tempering treatment）and pre rolling treatment（adding interlayer）on the composite plate.By summarizing the changes of microstructure and properties of composite plate under different test parameters,it provides a reference for improving the production process of C276/Q235B composite plate.After solution of C276/Q235B composite plate at 900,1000 and 1100℃for 0.5-2.5 h,Mo carbides layer is formed near the interface of C276 side.With the increase of temperature and time,the quantity of carbides increases,and the morphology of carbides changes from fine dispersion agglomeration to coarse network,and the effect of solution temperature on the quantity and morphology of carbides is significantly greater than that of solution time.The cross section hardness of C276/Q235B composite plate varies with the type and distribution of microstructures.The hardness distribution uniformity of C276/Q235B composite plate is better than that of other systems after solution at 1100℃for 2 h.The effect of solution treatment on corrosion resistance of C276 is mainly manifested in self-corrosion potential E_corrand passivation zone widthΔE₂.The self-corrosion tendency of the materials decreases with the increase of the temperature and then increases with the solution time,and the self-corrosion tendency is the lowest at1100℃for 2 h.Considering hardness uniformity of Q235B and corrosion resistance of C276,the optimal solution process is 1100℃solution for 2 h.On the basis of the best solid solution process,in order to further improve the toughness of the material,temper at 200,300,400,500 and 600℃for 1 h respectively.The results show that the number and morphology of C276 side carbides have not changed after tempering treatment.With the increase of tempering temperature,the hardness decreases as a whole.When the tempering temperature is 500℃,the martensite structure in Q235B changes and forms tempered sorbite structure.The hardness decreases most obviously and the toughness increases accordingly.After tempering treatment,the corrosion resistance of C276 is improved,and its self-corrosion tendency decreases first and then increases with the increase of tempering temperature.The self-corrosion tendency is the smallest at 500℃.The intergranular corrosion test also shows that the annual corrosion rate of C276 is the lowest when tempered at 500℃,which is 0.68 mm/year.After comprehensively measuring the toughness and corrosion resistance of the material,the optimum tempering temperature is 500℃.While exploring the post rolling heat treatment process of C276/Q235B composite plate,according to the production process,pure Ni and pure Fe layers with different thickness are added between C276 and Q235B in the blank assembly link to explore the influence of the addition of interlayer on the interfacial bonding strength and properties of C276/Q235B composite plate.The results show that the interfacial strength of C276/Q235B composite plate increases with the increase of interlayer thickness,and the addition of pure Ni layer is better than that of pure Fe layer,and the maximum shear strength is 312.9 MPa.The corrosion resistance of C276 increases with the increase of interlayer thickness,and the performance is the best when 0.5 mm pure Ni layer is added.