Si-CONTAINING HOT ROLLED STEEL SHEET WITH EXCELLENT CHEMICAL CONVERSION TREATMENT PROPERTY AND MANUFACTURING METHOD OF THE SAME

• Main Authors: YAMADA KATSUMI, FURUYA SHINICHI, MASUOKA HIROYUKI, TAIRA SHOICHIRO
• Format: Patent
• Language: English; Japanese
• Published: 31.03.2016
• Subjects: ALLOYS; CHEMICAL SURFACE TREATMENT; CHEMISTRY; CLEANING OR DEGREASING OF METALLIC MATERIAL BY CHEMICALMETHODS OTHER THAN ELECTROLYSIS; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATIONOR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY IONIMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING MATERIAL WITH METALLIC MATERIAL; COATING METALLIC MATERIAL; DIFFUSION TREATMENT OF METALLIC MATERIAL; FERROUS OR NON-FERROUS ALLOYS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUSMETALS OR ALLOYS; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION INGENERAL; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING OR OTHERTREATMENTS; METALLURGY; METALLURGY OF IRON; MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THESURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; TREATMENT OF ALLOYS OR NON-FERROUS METALS

PROBLEM TO BE SOLVED: To provide a Si-containing hot rolled steel sheet stably securing an excellent chemical conversion treatment property and an effective manufacturing method of the steel sheet.SOLUTION: In a manufacturing method of a hot rolled sheet steel where a pickling process, which includes an acid cleaning treatment, washing, and drying, is performed to a steel sheet after being hot rolled which includes Si of 0.5 mass% or more, and preferably has a composition of C:0.05-0.10 mass%, Si:0.5-1.0 mass%, Mn:1.0-1.5 mass%, P:0.010 mass% or less, S:0.004 mass% or less, Al:0.05 mass% or less, and N:0.0045 mass% or less, the acid cleaning of the acid cleaning treatment is performed by immersing the steel sheet in an acid cleaning bath at a temperature:70-90°C, with hydrochloric acid concentration:5-12 vol.% for 40 seconds or more, and a washing condition is adjusted such that 50% or more as an area ratio of a surface of the steel sheet is covered by a porous corrosion product.SELECTED DRAWING: Figure 1 【課題】優れた化成処理性を安定して確保できるＳｉ含有熱延鋼板およびその有利な製造方法を提供する。【解決手段】Ｓｉを０．５質量％以上含有し、好ましくは、質量％で、Ｃ：０．０５〜０．１０％、Ｓｉ：０．５〜１．０％、Ｍｎ：１．０〜１．５％、Ｐ：０．０１０％以下、Ｓ：０．００４％以下、Ａｌ：０．０５％以下、Ｎ：０．００４５％以下である組成を有する熱間圧延後の鋼板に、酸洗処理し水洗し乾燥する工程である酸洗工程を施し、熱延鋼板とする熱延鋼板の製造方法において、前記酸洗工程における酸洗処理を、温度：７０〜９０℃、塩酸濃度：５〜１２ｖｏｌ％の酸洗浴に４０秒以上浸漬する処理とし、水洗条件を調整して、鋼板表面がポーラス状の腐食生成物によって面積率で５０％以上被覆されているようにする。【選択図】図１