| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To reduce troubles required for production to attain the reduction in weight. <P>SOLUTION: A final cast iron article 13 in an oscillating pipe shape is formed from ductile cast iron. The cast iron article 13 formed from ductile cast iron is heated to 780°C which is an atmosphere adjusting sub-temperature, and held for one hour. Next, the cast iron article is heated to about 900°C which is an austenitizing temperature and held for 3.5 hours. Then, it is rapidly cooled to a bainitizing temperature ranging 260°C to 300°C, and held at the temperature for 1.5 hours, and then gradually cooled to produce a oscillating pipe 6a. This process imparts abrasive resistance as austemper ductile iron to the oscillating pipe 6a, and the cast iron article is held at the atmosphere adjusting sub-temperature for a predetermined time prior to so-called austemper processing, thereby reducing the distortion amount due to thermal treatment as compared with the case where austemper treatment is merely performed. <P>COPYRIGHT: (C)2005,JPO&NCIPI</p> |
