| 摘要 |
<p>[Problem] To provide a glow plug with which it is possible to improve heat resistance and durability in comparison with a heretofore known one. [Means for Resolution] A glow plug uses a sheathed heater with a heating coil housed in a sheath tube. The sheath tube, being formed from a nickel base alloy containing 21 to 30 percent by mass of chromium (Cr), 0.05 to 0.30 percent by mass of carbon (C), 1.0 to 2.4 percent by mass of aluminum (Al), and 0.1 to 0.3 percent by mass of one kind or more among titanium (Ti), zirconium (2r), and niobium (Nb), is such that when examining a metal structure in a circumferential transverse section of the sheath tube, the size of the metal structure has a variation of 2 or less in crystal grain size number according to JIS G0551 (2005), and Vickers hardness is within a range of 200 to 400.</p> |
