PTA Welding Parameters of Nickel-based Tungsten Carbide Alloy Powder

In response to demand in certain industries, Wisdom developed the nickel-based tungsten carbide powder WD+Ni(Cr), which is mainly used in the surfacing repair of equipment parts for mining, oil exploration and earthworks, for example stabilizer, scraper, knife roll and wear plate etc.

This product is a nickel-based composite alloy powder containing 65% tungsten carbide. The carbide has an angular microstructure, and the hard phase has a micro-hardness of 2200 to 2500 HV. Nickel-based alloys as the matrix phase can provide good wear resistance and uniform impact strength for the deposit layer. The wear-resistant phase - cemented carbide are uniformly distributed in the matrix, so after welding they are almost completely retained in the matrix. The matrix powder is manufactured by gas atomization, which improves the stability of the welding process.

The material can be used for hardfacing low carbon steel, stainless steel and nickel alloy substrates. Before welding, the base metal can be preheated to avoid any cracks entering the base metal. During a plasma transfer arc welding, the phase transition of tungsten carbide does not occur through a reasonable process. The matrix structure will not produce cracks due to carbon addition, so the overlay of PTA welding can eliminate the tendency of cracking.

Below are typical welding parameters of PTA process:

• Current: 100 – 140 A
• Voltage: 22 – 25 V
• Nozzle diameter: 3.2 mm
• Plasma gas: argon 2.2 – 2.8 L/min
• Feeding gas: argon 2.0 – 3.0 L/min
• Shielding gas: 15 – 18 L/min
• Welding speed: 7 – 10 cm/min
• Oscillation width: 14 – 18 mm
• Oscillation speed: 900 – 1200 cm/min
• Powder delivery: 50 – 120 g/min
• Gun height: 10 – 15 mm

Here are photos of metallographic structure: