The invention discloses a ferritic stainless steel sheet. An first embodiment of the ferritic stainless steel sheet contains 0.1 to 5.0 mass% inclusive of Cu and has a Cu-rich layer on the surface thereof, wherein the maximum concentration of Cu (Cm) in the Cu-rich layer is 10.0 mass% or more and the Fe/Cr ratio at a position at which the maximum concentration of Cu (Cm) is stood at, as observed from the surface of the steel sheet in the thickness direction, is 2.4 or more. A second embodiment of the ferritic stainless steel sheet contains 0.1 to 5.0 mass% inclusive of Cu and has a Cu-rich layer on the surface thereof, wherein the maximum concentration of Cu (Cm) in the Cu-rich layer is 18.0 mass% or more.

Ferritic stainless steel sheet having excellent anti-bacterial activity, and method for producing same

The invention relates to a continuous pickling method for a super austenitic stainless steel coil. The method comprises the following successive steps: I, connecting the front end and the rear end of a hot-rolled and annealed super austenitic stainless steel coil to duplex stainless steel coils; II, carrying out shot blasting on the super austenitic stainless steel coil at a low rotating speed before pickling; III, allowing the coil to pass through a chemical pretreatment section, with a medium being H2SO4 and a pickling speed being 13 to 18 m/min; IV, allowing the coil to pass through a first chemical mixed pickling section, with a medium being HNO3 + HF and a pickling temperature being 50 to 65 DEG C; V, allowing the coil to pass through a second chemical mixed pickling section, with a medium being HNO3 + HF; VI, allowing the coil to pass through a first water tank; VII, allowing the coil to pass through a second water tank; and VIII, cutting off the duplex stainless steel at the front end and the rear end of the hot-rolled and annealed super austenitic stainless steel. The surface of the steel coil pickled by using the continuous pickling method provided by the invention meets requirements on No. 1 plates by GB 4237, and high pickling efficiency is obtained.

Continuous pickling method for super austenitic stainless steel coil

PROBLEM TO BE SOLVED: To provide a method for pickling a ferritic stainless steel sheet including a step of performing pickling with a mixed acid liquid composed of hydrofluoric acid and nitric acid after pickling with sulfuric acid, the method capable of suppressing the generation of sludge without controlling the concentration of iron ions in the mixed acid liquid, and providing satisfactory pickling performance. SOLUTION: First to fourth pickling tanks 81 to 84 contain sulfuric acid. Fifth pickling tank 85 contains a mixed acid liquid composed of hydrofluoric acid and nitric acid. The mixed acid liquid has a concentration of the hydrofluoric acid of 20 to 150 g/L and a concentration of the nitric acid of 20 to 85 g/L. COPYRIGHT: (C)2009,JPO&INPIT

Method for pickling ferritic stainless steel sheet

Method of making a hot-rolled steel sheet having superior surface appearance, free of surface patterns and uneven glossiness from an austenitic stainless steel slab containing about 0.03 percent by weight or more of Cu, about 0.03 percent by weight or more of V, and about 0.01 percent by weight or more of Mo under any of the following conditions: (A) pickling in a nitric-hydrofluoric acid solution containing about 20 to 100 g/l of nitric acid and about 100 to 300 g/l of hydrofluoric acid; (B) controlling nitric-hydrofluoric acid content in response to the iron ion content in the solution; (C) a preliminary pickling step prior to finishing pickling; (D) grinding about 2 μm or more of the surface after preliminary pickling and prior to finishing pickling; (E) causing counterflow with a relative flow rate of 0.5 to 5.0 m/sec on the sheet surface during finishing pickling; (F) adding sulfuric acid or sulfurous acid as a hydrogen ion source to the nitric-hydrofluoric acid solution; and (G) electrolysing during finishing pickling such that the ratio of the cathodic electrolysis time to the anodic electrolysis time is about 3 or more.

Method of making austenitic stainless steel sheet

PROBLEM TO BE SOLVED: To continuously manufacture an HTS (high-temperature superconductor ) tape in a single step. SOLUTION: An unpolished metallic tape is provided, and a plurality of surface treatment units each having a polishing station and a water-washing station are provided. The unpolished metallic tape is continuously supplied to a first polishing station of the surface treatment unit, and a plurality of the continuous surface treatment units further polish the surface of the metallic tape using slurry-like abrasive media having a polishing material and water and having a particle size of the polishing material as small as a downstream polishing station. The metallic tape is passed through a series of surface treatment units, and the polished metallic tape is recovered from a final surface treatment unit. A cushioning layer is formed on the recovered metallic tape, and a high-temperature superconductive membrane is formed on the cushioning layer. The final surface treatment unit has a plurality of polishing rings, the particle size of the polishing material in slurry-like abrasive media in the final surface treatment unit is 0.05 μm or less. COPYRIGHT: (C)2008,JPO&INPIT

Method for manufacturing hts tape, and continuous machine polishing system

PURPOSE:To provide the method for treatment of a hot rolled austenic stainless steel strip which efficiently executes the removal of the surface scale, grain boundary oxide layers and the scale flaws of the steel strip by combining mechanical grinding and pickling and selecting the conditions thereof. CONSTITUTION:This method for treatment of the hot finished oustenitic stainless steel strip consists in subjecting the hot finished austenitic stainless steel strip to a grinding treatment of a 10 to 100mum surface range with a mechanical grinding means to remove the surface scale at least down to the grain boundary oxide layers, then subjecting the steel strip to a pickling treatment with a hydronitrofluoric acid pickling soln. which contains 30 to 210g hydrofloric acid per 1 liter hydronitrofluoric acid soln. mixture and 50 to 150g nitric acid and is kept at 50 to 80 deg.C until the amt. of scarfing attains 1 to 30mum. As a result, the grinding and pickling treatments are simplified and the efficiency thereof is enhanced. The product having excellent surface quality is obtd. and the improvement in productivity and the reduction of the production cost are resulted.

Treatment of hot finished austenitic stainless steel strip

PURPOSE:To efficiently remove surface scales and scale flaws of ferritic stainless steel hot rolled stock. CONSTITUTION:Ferritic stainless steel hot rolled stock is pickled by a soln. of sulfuric acid of 80 to 100 deg.C in which the concn. of sulfuric acid per 1 liter soln. is regulated to 200 to 400g and is thereafter pickled by a soln. of 40 to 80 deg.C whose cocn. is regulated to a one mixed with 20 to 160g nitric acid and 10 to 200g hydrofluoric acid per 1 liter soln. Furthermore, as for stainless steel hot rolled stock in which intergranular erosion is generated by the pickling by nitric acid hydrofluoric acid, its surface layer is dissolved and ground by 20mum by the pickling by sulfuric acid. By the combination of the pickling by sulfuric acid removing scales on the normal part and the pickling by nitric acid/hydrofluoric acid selectively and efficiently removing scale flaws, the productivity of the pickling of ferritic stainless steel hot rolled stock is remarkably improved.

Pickling method for ferritic stainless steel hot rolled stock

PURPOSE:To efficiently eliminate the scale and surface flaw of a stainless steel band, and to improve the surface quality of a cold rolling producing. CONSTITUTION:A stainless steel band, which is manufactured by hot rolling or thin casting, is ground by an elastic grinding roll in the range of the surface at 10-100mum in the condition for satisfying the formula I so as to eliminate the scale and the surface flaw, and continuously, the stainless steel band is melted for grinding by electrolytic pickling or electrolytic polishing in the condition for satisfying the formula II so as to eliminate the part left as it is not ground and grinding burr. 5mum<=A<=35mum...(I). 0.1XA<=B<=0.5XA...(II). A: surface roughness after grinding R max (mum). B: melting grinding quantity (mum/ single surface).

Komori Tadashi

Papers

Treatment of hot finished austenitic stainless steel strip

Pickling method for ferritic stainless steel hot rolled stock

Processing method and processing device line for stainless steel band