What are the key advantages of PTA overlays?

Accuracy: automated controls provide highest levels of consistency controlling heat input Quality: coating purity is extremely high with very little dilution into the base material Productivity: much higher production rates than other processes of similar quality (laser)

What causes porosity during welding?

In any welding process, porosity can be caused by the presence of contaminants or moisture in the welding zone, which includes the base metal, filler metal, shielding gas, and the surrounding atmosphere. Contaminants can include oil, dirt, grease, or cutting fluids. Concurrently, moisture can collect in the flux, shielding gas, or on the base metal,… Continue reading What causes porosity during welding?

What base materials can be over-layed?

Almost any steel, or stainless based alloy can be over-layed, including manganese based or non-magnetic materials.

What are the benefits of Hard-facing and Coatings ?

Reduces Cost: Restoring a worn part to “as new” condition generally costs between 20-70% of a brand new replacement part. Prolongs Equipment Life: Service life increases of 3 to 10 times are common with properly coated parts. Reduces Downtime: Parts last longer and fewer shutdowns are required. Less Spare Parts Inventory: There is no need… Continue reading What are the benefits of Hard-facing and Coatings ?

Can cast iron be hard-faced?

Yes, but you must take preheat and inter-pass temperatures into account. Nickel and nickel-iron products usually are suitable for rebuilding cast iron. These products aren’t affected by the carbon content of the parent metal and remain ductile. Multiple layers are possible. If further wear protection is required, metal carbide products can work well on top… Continue reading Can cast iron be hard-faced?

What is meant by a buildup or buffer alloy?

These alloys often resemble the parent metal alloy and are applied to severely worn parts to bring them back to dimension or act as a buffer for subsequent layers of a more wear-resistant hard-facing deposit. If the hard-facing produces check cracks, then it’s wise to use a tough manganese product as the buffer to blunt… Continue reading What is meant by a buildup or buffer alloy?

Why are some hard-facing products limited to two or three layers?

Limited-layer products usually are in the metal carbide families, such as chromium carbide and tungsten carbide. You can apply martensitic and austenitic products in unlimited layers unless the manufacturer specifies otherwise. The brittle nature of the metal carbides leads to check-cracking, and as multiple layers are applied, stress continues to build, concentrating at the root… Continue reading Why are some hard-facing products limited to two or three layers?

When is a cobalt or nickel hard-facing alloy used?

Cobalt alloys contain many types of carbides and are good for severe abrasion at high temperatures. They also have good corrosion resistance for some applications. Deposit hardness ranges from 25 HRC to 55 HRC. Work-hardening alloys also are available. Nickel-base alloys can contain chromium borides that resist abrasion. They can be good particularly in corrosive… Continue reading When is a cobalt or nickel hard-facing alloy used?

Must parts be preheated before hard-facing?

As a rule, you should bring all parts at least to room temperature. You can select higher preheat and inter-pass temperatures based on the base metal chemistry and hard-facing product you’re using.

What type of gas is used in PTAW hard-facing?

Low penetration and dilution are the major objectives in hard-facing, so pure argon and mixtures of argon with hydrogen generally will produce the desired result.