STEEL PLATE EXCELLENT IN LASER BEAM MACHINABILITY AND ITS PRODUCTION

• Main Authors: KAIZU TORU, KABASAWA MAKOTO, KOBAYASHI SATOO, OMURA MASAKI, URABE TOSHIAKI
• Format: Patent
• Language: English
• Published: 16.06.1998
• Edition: 6
• Subjects: ALLOYS; CHEMISTRY; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; FERROUS OR NON-FERROUS ALLOYS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUSMETALS OR ALLOYS; MACHINE TOOLS; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING OR OTHERTREATMENTS; MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVINGMATERIAL; METAL-WORKING NOT OTHERWISE PROVIDED FOR; METALLURGY; METALLURGY OF IRON; MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; PERFORMING OPERATIONS; PUNCHING METAL; ROLLING OF METAL; SOLDERING OR UNSOLDERING; TRANSPORTING; TREATMENT OF ALLOYS OR NON-FERROUS METALS; WELDING; WORKING BY LASER BEAM

PROBLEM TO BE SOLVED: To obtain a steel plate restraining the development of a notch at the time of machining with a laser beam despite having a composition in the range of general steel plate materials and excellent tin a laser beam machinability by forming a scale layer containing a specific quantity of magnetic on the surface of the steel plate. SOLUTION: In order to improve the machinability when treating the steel plate with the laser beam, a scale having <=15μm thickness is formed so that the developing quantity of the magnetite in the scale becomes >=15vol% (the balance is substantially wustite). In order to simultaneously control the thickness of this scale and the developing quantity of the magnetite, at the time of hot- rolling directly or after rehashing the hot steel slab obtd. by the continuous casting, descaling is executed before hot-rolling and during rolling to remove the scale developed during heating and rolling. Further, parameters of the comprehensive predicting conditions composed of the last draft and the rolling temp. in a finish-rolling and the cooling speed and the coiling temp. just after the finish-rolling, are controlled.