Spark plug and method of producing spark plug

摘要

A spark plug (100) includes: a central electrode (3); an insulator (2) surrounding the central electrode (3) radially; a metallic shell (1) surrounding the insulator (2) radially; and a ground electrode (4) having a first end connected to the metallic shell (1) and a second end defining a side face. The ground electrode (4) is so bent that the side face of the second end faces the central electrode (3). The ground electrode (4) contains: a nickel in a range from 58% to 71% by weight, a chromium in a range from 21% to 25% by weight, an iron in a range from 7% to 20% by weight, and an aluminum in a range from 1% to 2% by weight. The ground electrode (4) has a Vickers hardness in a range from Hv 140 to Hv 220 through a Vickers hardness test specified in Japanese Industrial Standard Z2244. A load 9.8 N is applied to the ground electrode (4) in the hardness test.