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AVW- Austenitic Stainless Steel

Steel data sheets

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Valbruna Grade

AVW

Steel type

Austenitic Stainless Steel

Description of material

AVW is a Cr- Ni -Si austenitic stainless steel designed for elevated temperature applications whose Tungsten content warrants a good mechanical strength and hot corrosion resistance.

Applications

Exhaust valves for gasoline and diesel internal combustion engines where a high temperature strength and corrosion resistance to combustion products are needed. This grade is normally used in the production of not heavy duty exhaust valves with an operating temperature not over 720°C.

Corrosion resistance

AVW has a good resistance to oxidation and corrosion to combustion products that form inside the engine. When solution treated, this grade offers a stable austenitic structure.

Cold working

AVW has a fair ductility in the annealed condition, and cold shearing, band or circular sawing and grinding wheel cutting can be used. In the case of turning, its machinability is approximately comparable to the strain hardened austenitic TP 300 series and could be only improved with a right choice of cutting fluids, tools and machining parameters.

Weldability

In solid state joining such as Friction Welding, AVW provides a quality bond line. When friction welded with stems of alloy or martensitic steels, a stress relieving or tempering of the valve must be done in order to soften the martensitic structure of HAZ and bond line.

Hot working

AVW has a good hot plasticity and is suitable for processing by hot extrusion or by upsetting with electric resistance heating. However, overheating must be always avoided. The choice of hot working temperature and process parameters must always evaluate both the strain rate and the consequent increasing of temperature that is reached after hot deformation. High strain rates and temperatures at the top end of the range during the extrusion and forging process, could generate internal bursts of the stem of valve. The same care for electrical upsetting process must be carried out, in order to maintain the right geometry of the bulb and to avoid hot cracks and internal shortness of the head valve. A low or medium temperature range of hot working is recommended.

Heat treatment

Heat treatments do not increase the mechanical properties of AVW and only full annealing and stress relieving after friction welding can be done.

Designations

W.N. 1.4873
EN X45CrNiW18-9
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