Common Hydraulic Fitting Alloys: Brass, Carbon Steel, and Alloying Elements

Alloy steels begin with carbon steel and add other elements to change performance. Aluminum, chromium, copper, manganese, nickel, silicon, titanium, and other additions can increase hardness, strength, wear resistance, heat resistance, or corrosion resistance.

For fittings and industrial components, material choice affects pressure capability, corrosion behavior, cost, manufacturability, and service life.

Brass

Brass is an alloy of copper and zinc. Different proportions create different mechanical and electrical properties, which is why brass appears in pipe fittings, threaded fasteners, tube fittings, and flare fittings.

Brass is often used where corrosion resistance, machinability, flexibility, and durability are needed. It is common in plumbing and some lower-pressure fluid applications, but it must still match the pressure, media, and temperature.

Carbon Steel

Carbon steel combines iron and carbon, often with small amounts of elements such as copper, manganese, or silicon. It is widely used because it offers strength and cost advantages across industrial, construction, and agricultural equipment.

Carbon steel has limited corrosion resistance compared with stainless steel and some specialty alloys, so coatings, plating, environment, and maintenance should be considered.

Common Alloying Elements

Chromium can add hardness, toughness, and wear resistance. Chromium-vanadium can increase tensile strength while improving malleability for bending and cutting. Cobalt withstands high heat and is often associated with cutting tools.

Manganese improves surface hardness, shear strength, and resistance to shock. Molybdenum increases strength and heat resistance. Nickel improves corrosion resistance and strength. Tungsten improves grain structure and heat resistance, while vanadium can improve strength, toughness, corrosion resistance, and shock resistance.

Choosing Materials for Fittings

Brass, carbon steel, stainless steel, and specialty alloys all have a place. The correct choice depends on pressure, media, corrosion exposure, vibration, temperature, standards, and cost target.