| ‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘ KAWASAKI STEEL TECHNICAL REPORT No.25 ( September 1991 ) Special Issue on 'H-Shapes with Fixed Outer Dimension' and 'Steel Pipe' ‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘ |
| Weld Zone Toughness of ERW Ti-Stabilized 11% Cr Steel Pipe for Automobile Exhaust Systems Atsushi Miyazaki, Tatsuo Kawasaki, Takaaki Toyooka, Junichi Karasawa, Osamu Hashimoto |
|
Synopsis : The toughness of weld zone of ERW Ti-Stabilized 11% Cr steel pipe produced by a "chance-free" bulge roll (CRB) forming pilot mill was investigated. The weld zone, particularly HAZ, had its toughness markedly lower than in the base metal. The reason for this embrittlement was examined by investigating precipitant behavior of Ti and Cr through laboratory-scale various heat treatments. As a result, the embrittlement of HAZ is considered to have been due to the following metallurgical factors: (1) Cr-carbides formed during cooling by the partial dissolution of TiC at high welding temperatures, (2) solute C supersaturated by rapid cooling after welding, and (3) undissolved TiN remaining even at high welding temperatures. Consequently, a reduction in the carbon and nitrogen content would improve HAZ toughness of ERW pipe. |
| TextiPDF: 8p./405kbj |