Research On The Interfacial Structure And Mechanical Properties Of Vacuum Hot Rolled 316L/14Cr1MoR Stainless Steel Clad Plates

With the continuous development of modern industry,our country’s large-scale containers service life has been drastically shortened,and the service environment of these containers has become more stringent,resulting higher requirements for container steel in terms of corrosion resistance and application performance.The stainless steel clad plate has the advantages of both the high structural strength of the base carbon steel and the corrosion resistance of the composite stainless steel.It is expected to replace the traditional container steel and gradually become the most promising new material.Due to its green,environmental protection,and high efficiency characteristic,vacuum hot-rolling has become one of the most widely used preparation technologies of stainless clad plates.In this paper,14Cr1 Mo R low-alloy container steel was selected as the base material,and 316 L ultra-low carbon austenitic stainless steel was used as the composite material.The316L/14Cr1 Mo R stainless clad plate was prepared by the vacuum hot rolling process.Means of microstructure characterization methods such as metallographic(OM),scanning(SEM),transmission electron microscopy(TEM)were performed.Shear strength,tensile strength,impact and other mechanical properties were tested.The effects of the rolling process(rolling temperature,reduction ratio)and heat treatment process on the microstructure and mechanical properties of the stainless steel composite plate interface were studied,and the process area of heat treatment and hot rolling process were optimized.To study the effect of rolling process on the interfacial structure and mechanical properties of stainless steel clad plate,the rolling bonding process was simulated on the Gleeble-3500 thermal simulation system.By controlling the rolling process parameters,vacuum hot-pressed composite samples with different rolling temperatures and rolling reduction rates were obtained,and the structure and properties of the composite samples were characterized.The results show that with the increase of rolling temperature and reduction ratio,the number and size of interfacial inclusions are significantly reduced,enhancing the interfacial bonding,and the shear strength were significantly increased.When the hot rolling temperature was 1200℃ and the rolling reduction rate was 70%,the highest shear strength of the composite sample was gotten,which was considered as the best process.In addition,after the composite sample was bent 180° internally nor externally,there was no obviously interfacial cracking,indicating the bending performance meets the application requirements.Under the best rolling process,vacuum hot-rolled clad plates were prepared by vacuum symmetrical billet assembly and vacuum electron beam welding technology.The rolled clad plates were subjected to a series of temperature heat treatment experiments(600℃,700℃,800℃,900℃,and 1000℃),the microstructure and mechanical properties of the heattreated clad plates were characterized.The results show that with the increasing of heat treatment temperature,the width of decarburized layer and carburized layer first increase and then decrease,and the shear strength and ultimate tensile strength first decrease and then increase.When the heat treatment temperature is 800℃,the decarburized layer and carburized layer reach the widest,and the shear strength and tensile strength reach the lowest value,which are 390 MPa and 645 MPa,respectively.The wider decarburized layer and carburized layer are the main factors of deterioration of shear and tensile properties.At900℃ and 1000℃,the carbides start to dissolve,the width of decarburized layer and the carburized layer gradually decrease,and the shear performance and transverse tensile performance are improved.The impact fracture behavior of the substrate are mainly cleavage brittle fracture.When the heat treatment temperature is 600℃ and 700℃,the area of the fan-shaped dissociation plane of the substrate on the impact fracture is small and partially area contains small dimples,the fracture mode is changed from cleavage fracture to mixed fracture,and the impact performance become better.However,an excessively high heat treatment temperature will result in coarsening of the crystal grains,which will decrease the impact energy.In summary,the suitable heat treatment temperature should be between 600℃ and 700℃.