The Development And Application Of Stainless Steel Composite Plates For Bridges

The corrosion resistance and service life of the bridge can be significantly improved by using stainless steel and bridge steel composite plates instead of the traditional carbon steel,because of its good strength and toughness match and excellent corrosion resistance.The vacuum rolling method is a new type of composite board production method,which has the advantages of green environmental protection and stable production performance.However,there are few studies on the influence of rolling process parameters on the microstructure and mechanical properties of the composite surface.In this research,316 L stainless steel was selected as the composite material,and two different compositions of Q370 qD low carbon steel were used as the base material to study the effects of different substrate components on the mechanical and corrosion properties of the composite sheet,and then optimize the composition of the base material;the composite lamination process was simulated by Gleeble-3500.After the tests,the interdiffusion law,structure and properties of interface elements of simulated stainless steel composite plates were investigated by using optical microscopy(OM),scanning electron microscopy(SEM)and shear test,to optimize the optimum rolling process parameters.Based on the optimized parameters,the industrial trial production of 316L+Q370qD stainless steel clad plate was carried out,and the comprehensive mechanical properties of the base metal and the weldability,fatigue and corrosion resistance of the composite plate were evaluated.The results are as follows:When the carbon content of the composite board base material is reduced from 0.15 wt.% to 0.10 wt.%,the intergranular corrosion resistance of the composite sheet weld layer is significantly improved,and the optimized carbon content range is ?0.10 wt.%.As the rolling temperature increases,the diffusion distance of the interface elements increases,the corresponding shear strength increases,and the bonding performance of the interface are improved;While,as the rolling reduction increases,the size of oxides and inclusions gradually decreases,and finally disappears,the diffusion distance of elements decreases gradually,the shear strength increases gradually,and the interface bonding performance are improved.The optimized rolling composite process is: billet heating temperature ?1150 ?,the total rolling reduction rate ?70%.The industrial trial production of 316L+Q370qD stainless steel clad plate was carried out according to the optimized composition and rolling process.The re-inspection results show that the shear strength of the composite interface is above 484 MPa,which is much larger than the standard value of 210 MPa.In addition,the trial composite panel has excellent breaking performance,which is manifested in: the ductile-brittle transition temperature of the composite layer side and the base layer side are lower than-30 ?;the aging sensitivity coefficient of the composite layer and the substrate are ? 15%;After twisting at 1440°,the bonding interface between the composite layer and the base layer is intact;the shrinkage ratio of the Z-direction tensile section reaches Z35.The weldability,fatigue and corrosion resistance of the trial-made stainless steel clad plates were evaluated.The results show that the trial composite panels have lower hardenability and low weld crack sensitivity;stainless steel clad plates and composite plate welded joints have good Fatigue performance,the conditional fatigue limit of 2×106 cycles reached 395 MPa and 340 MPa respectively;the intergranular corrosion performance of welded joints of stainless steel clad plates and composite plates were all qualified.