Process Research On Vacuum Hot Roll-Clad For 825 Alloy/X65 Pipeline Steel

825 nickel-based corrosion resistant alloy has excellent corrosion resistance,mainly used in petroleum chemical industry,ocean engineering,energy and other industrial departments,but its expensive price limits its wide application.In the form of clad plate can be largely reduced its applications cost.825 nickel-based corrosion resistant clad plate not only has good corrosion resistant properties of 825 alloy,but also has fine mechanical properties of base material.Currently,abroad the use of vacuum hot roll-cladding technology for 825 nickel-based corrosion resistant clad plate is relatively mature,but domestic mainly adopt the method of explosive composite to manufacture 825 corrosion resistant clad plate,the properties of clad plate with foreign has a larger gap.Therefore,in order to link international market,it is necessary to research of the technology of vacuum hot roll-cladding of 825 nickel-based corrosion resistant clad plate.This paper based on "the the project of manufacture of 825 nickel-based corrosion resistant clad plate of Nanjing Steel Company " to research the process route of vacuum hot roll-cladding of corrosion resistant alloy 825/X65 pipeline steel clad plate,worked out the technology of electron beam welding and roll-cladding of 825 corrosion resistant alloy/X65 pipeline steel,and master the technology of vacuum hot roll-cladding 825 corrosion resistant clad plate,has manufactured clad plate with excellent properties which reached the international leading level.And the following conclusions are obtained:(1)Vacuum electron beam welding is suitable for welding of 825 alloy/X65 steel,and the suitable electron beam welding process parameters is:welding current 70 mA,focusing on 10 mA,welding speed 400 mm/min,the welded joint by this welding process parameters can ensure no crack in the rolling process,guarantee the interface of high vacuum degree,and can meet the requirements of the experiments.(2)The process route of preparation of 825 corrosion resistant clad plate is:use hydrochloric acid pickling + polished by steel to handle billets surface,vacuum electron beam welding machine is used to welding the composite slab all around,the composite slab with furnace heated to 1150?,keeping 2h,adopt two-phase rolling method,rolling ratio is 65%or higher,adopt the method of accelerated cooling after final rolling(cold speed>10?/s),cooled to 500?600 ?,Then air cooling to room temperature.(3)825 corrosion resistant clad plate tensile-shear strength of the interface is more than 360 MPa and meet the minimum standards(shear strength ? 320 MPa).With the increase of rolling ratio,the bond strength of composite interface basically remains unchanged,but the grain size of clad plate decreases with the increase of rolling ratio.Composite interface accompanied by dotted Al-O compound inclusions and linear distribution of TiC inclusions,tension-shear section is locate at TiC inclusions which distribution is linear.Base material of clad plate after rolling with good mechanical properties,tensile properties and impact properties can meet the requirements,compound layer has excellent corrosion resistance,and pitting corrosion resistance performance and intergranular corrosion resistance performance are all accord with the minimum standards.(4)Heat deformation resistance of 825 alloy higher than X65 steel,which is about2-3 times of X65 steel.In the form of asymmetric rolling,the deformation level of base material X65 steel lower than compound layer 825 alloy.Symmetrical rolling can change the forced deformation of the composite slab during rolling,leading to coordination deformation between base material and compound layer,and 825 alloy in accordance with the deformation level of X65 steel.The recrystallization degree of symmetry rolling higher than asymmetric rolling,clad plate can have a fine uniform organization with symmetry rolling.(5)Composite interface of clad plate in the form of symmetric rolling tensile-shear strength is 404 MPa,higher than the strength of asymmetric rolling about 40 MPa.composite interface of clad plate in the form of symmetric rolling contains a small amount of dotted Al oxides,TiC inclusions which distribution is linear,which makes the symmetrical rolling tensile-shear strength higher than symmetrical rolling,tension-shear section is locate on X65 steel matrix.Suggest using the form of symmetric rolling in actual production process.