Coordination Mechanism Of Stainless Steel/Carbon Steel Clad Plate And Research On Co-Enhancement Of Strength And Plasticity In Matrix Steel

Stainless steel/carbon steel clad plates are widely used in nuclear power,petrochemical and other major fields because of their excellent corrosion resistance and good strength.At present,the problem of stainless steel/carbon steel clad plate is that the interface bonding is not uniform and the strength is not high enough,which leads to the interface delamination and fracture in the service process,thus affecting its applicability.In order to solve these problems,the 304 stainless steel/Q235 carbon steel(SS/CS)clad plates were successfully prepared based on the vacuum diffusion bonding(VDB)method in this paper.The effect of process parameters on mechanical properties was explored,and the relationship between the interfacial microstructure and properties and the coordination mechanism of interfacial dislocations during deformation were clarified.At the same time,the possibility of co-enhancement of strength and plasticity of the alloy steel for the clad plate was explored.The details are as follows:(1)The effects of heating temperature,holding time and loading pressure on the mechanical properties of clad plates obtained by direct VDB were investigated.The results show that the maximum shear,tensile and bending strength values were obtained when the clad plate was prepared at 800°C under 15 MPa for 120 min.The good mechanical properties are attributable to the fact that metallurgically bonded interfaces had been constructed between the stainless steel and the carbon steel.(2)High resolution transmission electron microscopy(HRTEM)was used to overcome the difficulty of the large difference between the bands of the ferrite and the austenite crystals,and realize the formation of clear high-resolution images of the ferrite and austenite at the same time.Three types of interface coordination mechanisms that occur at the ferrite–austenite interface during the clad plate deformation are proposed.(3)The Burgers vector of dislocation measurements were carried out by using two-beam method of TEM electron diffraction contrast image(EDCI)technology and high-resolution TEM imaging.Two types of dislocation reactions may have occurred at the ferrite–austenite interface during the SS/CS clad plate deformation,i.e.a/2[111]→a/6[111]+a/3[111]on the ferrite side of the interface,and /2[110]→a/3[111]+a/6[11(?)]on the austenite side of the interface.(4)The possibility of co-enhancement of strength and plasticity of the steel for the clad plate was explored.The composition of alloy steel was adjusted,and the effects of heat treatment processes on the strength,plasticity and microstructure of alloy steel were investigated.The results showed that the strength-elongation product of the original sample reached 27633.4 MPa·%,which had the possibility of strength and plasticity co-increase.