| 摘要 |
PURPOSE:To improve the heat resistance of an Al (alloy) covered steel material by heat treating the steel material at a specified temp. to convert the Al (alloy) layer into an Al-Fe intermetallic compound layer and by forming a heat and corrosion resistant paint film. CONSTITUTION:An Al (alloy) plated or clad steel material may be used as an Al (alloy) covered steel material as a starting material, and the preferred Al alloy is an Al-Si alloy contg. 1-15wt% Si. The steel material is heat treated at >=350 deg.C, especially at a temp. which is above the service temp. by >=50 deg.C to convert the Al (alloy) layer into an Al-Fe intermetallic compound layer. The heat treatment time is made >=2 times the time required to convert the Al (alloy) layer into the compound layer so that the compound layer is thermally stabilized. After the heat treatment the compound layer has a structure whose principal phase is one or more among FeAl3, Fe2Al5, FeAl and Fe3Al. The steel material is then coated with heat and corrosion resistant paint such as silicone resin paint. |
