Stainless steel clad plate with excellent shape and preparation method thereof

A preparation method of a stainless steel clad plate, wherein the method comprises the following steps:

• (1) composite slab preparation
• preparing two carbon steel slabs with a thickness of T1, a length of L1, and a width of W1 as a base material;
• and preparing two stainless steel slabs with a thickness of T2, a length of L2<L1, and a width of W2<W1 as a cladding material;
• performing surface treatment on at least one surface of each of the two base materials and two cladding materials;
• applying a separating agent on one surface of one cladding material;
• stacking slabs in an order of a base material, a cladding material, a cladding material, a base material;
• the cladding material is placed centrally relative to the base material, surfaces of the base material and the cladding material that contact each other are all surfaces subjected to the surface treatment, and surface coated with the separating agent faces another cladding material;
• preparing four sealing strips with a width of W3, where W3=2T2−(1~2) mm, attaching the sealing strips to four side edges of the two cladding materials, performing gas shielded welding between adjacent sealing strips and between the sealing strips and the base materials to form the two base materials and sealing strips into an integral whole, obtaining a composite slab blank;
• machining a circular hole on the sealing strip in a groove at the side edge of the composite slab blank, welding a seamless steel tube at the circular hole;
• performing surfacing welding on the grooves at four side edges of the composite slab blank;
• performing three times of vacuuming and two times of vacuum breaking on the composite slab through the seamless steel tube, finally making the vacuum degree ≤10−2 Pa;
• and then performing sealing treatment on the seamless steel tube to obtain a composite slab;
• (2) composite slab rolling
• heating the composite slab, and then performing two-stage controlled rolling of rough rolling+finish rolling;
• performing cooling after rolling:
• the unified clad plate enters ultra-rapid cooling system for intermittent cooling;
• the ultra-rapid cooling system has 24 groups of cooling headers arranged at an interval of 1 m along a roller table, a cooling distance of each group of cooling headers is 1 m;
• when the unified clad plate passes through the ultra-rapid cooling system, the operation of all 24 groups of the cooling headers is controlled in a periodic pattern consisting of N consecutive activated groups followed by M consecutive deactivated groups of cooling headers repeated as necessary;
• a cooling water pressure is 0.15~0.30 MPa, a cooling rate is 3~15° C./s, and a final cooling temperature is 380~590° C.;
• wherein N takes a value of 2, 3 or 4, and M takes a value of 2, 3 or 4;
• after exiting the ultra-rapid cooling system, the unified clad plate is directly entering straightening in a straightening machine;
• and then placing straightened unified clad plate between two steel plates at a temperature of Tf−150° C.~Tf+150° C. for stacked cooling;
• a stacked cooling time is 0.4 min/mm×10±5 min (t0 is a thickness of unified clad plate);
• the unified clad plate is air-cooled on a cooling bed until room temperature after stacked cooling;
• Tf=550+30Si−20Mn+15Cr−15Ni+10Mo, where the element symbols represent 100 times the mass percentage of the respective elements in base material;
• (3) clad plate separation and straightening
• cutting an edge of the unified clad plate to remove a portion outside the sealing strip, thereby separating the unified clad plate into an upper clad sub-plate and a lower clad sub-plate;
• placing the sized clad sub-plate on a leveling machine with a cladding layer facing upward for a leveling;
• when performing a transverse leveling, controlling a leveling force of the leveling machine to be F1=v×a×b×ct×σt/(d×(v−ct/a));
• when performing a longitudinal leveling, controlling a leveling force of the leveling machine to be F2=a×b×cl×σ1/(d+cl);
• the a denotes a width of the clad sub-plate, b is a thickness of the clad sub-plate;
• the ct denotes a flatness deviation per meter in the transverse direction of the clad sub-plate, measured in mm;
• the cl denotes a flatness deviation per meter in a longitudinal direction of the clad sub-plate, measured in mm;
• the d denotes a working distance of the leveling machine, σt denotes a tensile yield strength in the transverse direction of the clad sub-plate, σl denotes a tensile yield strength in the longitudinal direction of the clad sub-plate, and v denotes a Poisson's ratio;
• finally, performing a cold straightening on the clad sub-plate to obtain a single-sided stainless steel clad plate product.