690 is used as a mould material in the glass container industry and other high temperature controlled heat transfer applications with severe wear conditions at elevated temperatures. Although slightly more susceptible to sulfur corrosion than 700XX, the ability to maintain consistent linear expansion during the heating and cooling cycles makes alloy 690 the perfect choice for glass container bottle moulds.
690 has a time proven ability to resist corrosion in the glass making environment. When using 690, avoid using sulfur based swabbing compounds as release agents in either the blank or finish operation. Compounds used on the blank side will generally carryover to the finish side. When swabbing compounds containing sulfur are used in repeated production cycles, the sulfur will attack the aluminum and an orange peel texture will develop on the casting surface. To increase mould life, use a non sulfur based swabbing compound.
For repair of 690 castings, TIG welding is recommended. Suggested filler metal for TIG welding is Ampco – Trode 46. Gas should be 100% argon. Spray welding is also an acceptable procedure for repair of 690 castings. Use a Nickel based powder for filler metal in the spray welding procedure. Castings being repaired using one of the above mentioned methods is to be preheated to 500° F- 800° F, depending on process and casting size.
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