Precision Investment Casting of Super Duplex Stainless Steel with CNC Machining

Duplex Stainless Steel (DSS) refers to stainless steel with ferrite and austenite each accounting for about 50%. Generally, the content of less phases needs to be at least 30%. In the case of low C content, the Cr content is 18% to 28%, and the Ni content is 3% to 10%. Some duplex stainless steels also contain alloying elements such as Mo, Cu, Nb, Ti, and N.

The DSS has the characteristics of austenitic and ferritic stainless steel. Compared with ferrite, it has higher plasticity and ductility, no room temperature brittleness, and significantly improved intergranular corrosion resistance and welding performance, while still maintaining brittleness, high thermal conductivity, and superplasticity as ferrite stainless steel. Compared with austenitic stainless steel, DSS has high strength and significantly improved resistance to intergranular corrosion and chloride stress corrosion. Duplex stainless steel has excellent pitting corrosion resistance and is also a nickel-saving stainless steel.

▶ Casting Process of Super Duplex Stainless Steel - Lost Wax Investment Casting
Investment (lost wax) casting is a method of precision casting complex near-net-shape details using replication of wax patterns. It is a metal forming process that typically uses a wax pattern surrounded by a ceramic shell to make a ceramic mold. When the shell dries, the wax is melted away, leaving only the mold. Then the casting component is formed by pouring molten metal into the ceramic mold. Also called precision investment casting, lost wax casting could achieve complex forms with exceptional surface qualities for both small and large casting parts in a wide range of materials such as carbon steel, alloy steel, stainless steel...etc. lost wax casting offers tighter dimensional tolerances, better surface finishes, produces near-net shape parts which therefore require less machining and other processing, and allows for the steel casting of complex-geometry parts and intricate details such as casting marks and company logos.

▶ Advantages of Investment Casting Components by Duplex Stainless Steel

• Excellent and smooth surface finish

• Tight dimensional tolerances.

• Complex and intricate shapes with design flexibility

• Capability to cast thin walls therefore a lighter casting component

• Wide selection of cast metals and alloys (ferrous and non-ferrous)

• Draft is not required in the molds design.

• Reduce the need for secondary machining.

• Low material waste.

▶ Capabilities of Cast Duplex Stainless Steel Components

• Max Size: 1,500 mm × 1000 mm × 500 mm

• Weight Range: 0.1 kg - 500 kg

• Annual Capacity: 5,000 tons - 6,000 tons

• Tolerances: On Request.

▶ How We Inspect the Cast Duplex Stainless Steel Components:

• Spectrographic and manual quantitative analysis

• Metallographic analysis

• Brinell, Rockwell and Vickers hardness inspection

• Mechanical property analysis

• Low and normal temperature impact testing

• Cleanliness inspection

• UT, MT and RT inspection

▶ Post-Casting Process

• Deburring & Cleaning

• Shot Blasting / Sand Peening

• Heat Treatment: Normalization, Quench, Tempering, Carburization, Nitriding

• Surface Treatment: Passivation, Anodizing, Electroplating, Hot Zinc Plating, Zinc Plating, Nickel Plating, Polishing, Electro-Polishing, Painting, GeoMet, Zintec

• Machining: Turning, Milling, Lathing, Drilling, Honing, Grinding,

▶ Application of Duplex Stainless Steel Castings:

• Building hardware

• Machinery Components

• Railway Freight Cars

• Marine Hardware

• Hydraulics Cylinders

• Valve and Pump Spare Parts

• Agricultural Equipment

To know better about our capabilities of lost wax casting, please click the following picture to turn to our page of Investment Casting Capabilities: