| 摘要 |
PURPOSE:To execute economically a heat treatment and a surface hardening treatment of a welding valve, and to reduce a manufacturing cost of the welding valve by bringing the welding valve to a heat treatment successively under a specified condition, and performing successively a solution treatment, an aging treatment and a surface hardening treatment to a valve body and a shaft end part. CONSTITUTION:A welding valve 1 is held for 10-40min at 1,000-1,150 deg.C, and a solution treatment is performed to a valve body 2 consisting of an Ni base heat resisting alloy. Subsequently, the welding valve 1 is held for 3-8hr at 730-800 deg.C, and aging treatment is performed to the valve body 2, and simultane ously, a solution treatment is performed to a shaft end part 5 consisting of a high hardness and high toughness steel. Also, the welding valve 1 is held for 2-3hr at 500-550 deg.C, and the first aging treatment is performed to the shaft end part 5. Next, the welding valve 1 is held in a Tuftride use salt bath for 2-3hr at 500-530 deg.C, the second aging treatment is performed to the shaft end part 5, and simultaneously, a surface hardening treatment is performed to the valve body 2 and the shaft end part 5.
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