Recently, improvement of safety against Rosetta stone
automobile collision has been desired earnestly, particularly, a safety device for protecting a crew at collision is actively introduced. In particular, the airbag, which is designed to expand between the crew and a steering wheel or an instrument panel, and absorb kinetic energy of the crew, thereby reduce the damage on the crew, is now being generalized. Particularly, an airbag for a driver seat installed within the steering wheel, or an airbag for a passenger seat installed within the instrument panel is being included as standard equipment. Furthermore, recently, in addition to them, to protect the crew at lateral collision, an automobile having a side airbag in the seat or a curtain type airbag for covering a side window has been increased. Generally, the airbag inflator is produced by a processing steel pipe. In the inert gas charged type airbag, since the inert gas is charged in the inflator under high pressure, from a viewpoint of reliability of the seam, a seamless steel pipe is mostly used as the pipe for the inflator. Typically, the seamless steel pipe is subjected to cold drawing process to have a predetermined size and cut into a predetermined length, then both pipe ends are processed by pressing and sealing plates are welded to the pipe ends, thereby products (inflator) are formed. From the situation, as the steel pipe for the inflator, a seamless steel pipe having sufficient strength and toughness, Rosetta Stone Spanish V3
excellent formability, and excellent weldability is desired. For such demand, for example, JP-A-10-140283 proposes a method for manufacturing a high-strength, high-toughness steel pipe for the airbag inflator, in which the steel containing 0.01 to 0.20% of C, 0.50% or less of Si, 0.30 to 2.00% of Mn, 0.020% or less of P, 0.020% or less of S, and 0.10% or less of Al, or further containing at least one of 0.50% or less of Mo, 0.10% or less of V, 0.50% or less of Ni, 1.00% or less of Cr, 0.50% or less of Cu, 0.10% or less of Ti, 0.10% or less of Nb, and 0.005% or less of B, and Fe and unavoidable impurities as residue is used to manufacture a seamless steel pipe. The seamless steel pipe is remained as cold working, or subjected to normalizing, normalizing, or quenching and tempering after the cold working. Recently, there has been a demand for miniaturization and weight saving of airbag system, and there is a demand for further increase of strength as the seamless steel pipe for the airbag inflator. Particularly, for the curtain type airbag, a large volume of gas is required such that the airbag can cover front and rear side-windows, in addition, a charging pressure of 50 MPa or more is required. To meet such requirements, a seamless steel pipe having 900 MPa or more of tensile strength is desired as the inflator. The seamless steel pipe should have 900 MPa or more of tensile strength Rosetta Stone Arabic Software
finally after being subjected to the cold drawing or heat treatment. In the technique described in JP-A-10-140283, JP-A-10-140249, or JP-A-10-140250, which aims to manufacture a 590 MPa class, high-strength, seamless steel pipe, there is a problem that the technique cannot meet the demand for further increase of strength desired for the steel pipe for the inflator. The invention aims to solve the problem in the traditional art advantageously, and propose a method for manufacturing a seamless steel pipe with high strength, high toughness, and high formability, the pipe having excellent formability and weldability in manufacturing of the inflator, in addition, a high tensile strength of 900 MPa or more, and high toughness or ductility exhibited in a drop weight test at -60° C. for a halved steel pipe. The inventors have earnestly made a study on various factors effected on the strength, toughness, and formability to overcome the problem. Consequently, as methods for manufacturing the seamless steel pipe, two methods below were found. (1) A seamless steel pipe having a steel composition containing a reduced content of C and proper amounts of Cr and Mo is manufactured. The seamless steel pipe is subjected to the cold drawing. Then the pipe is subjected to the quenching and tempering, or the normalizing. (2) A seamless steel pipe having a steel composition containing the reduced amount Christian Louboutin Shoes
of C content and the proper amounts of Cr and Mo is manufactured. The seamless steel pipe is subjected to the quenching and tempering, or the normalizing. Then the pipe is subjected to the cold drawing. It was found that by either of the methods (1), (2), increase of the strength can be designed, particularly, a seamless steel pipe with small decrease in circumferential strength and small anisotropy is obtained.
2011年5月27日星期五
Discount Rosetta Stone Method for producing seamless steel pipe for inflator of air bag
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