Stainless Steel 422 Round Bar / SAE 422 Rods / AISI 422 Bars

Product Description

AISI 422 (UNS S42200 / Type 422) is a hardenable, martensitic stainless steel engineered primarily for high-strength service at elevated operating temperatures.

While baseline martensitic grades like AISI 410 or 420 begin to lose their structural properties above 900°F (482°C), AISI 422 maintains excellent creep-rupture strength, high resistance to scaling, and structural integrity at continuous service temperatures up to 1200°F (649°C). This stability makes it a core material for high-stress components in steam turbines, aerospace systems, and power plants.

1. Chemical Composition (Weight %)

The elevated high-temperature performance of 422 stainless steel is achieved by introducing transition metal carbide-formers (tungsten, vanadium, and molybdenum) into a higher-carbon chromium matrix.

2. Mechanical Properties (Typical Room-Temp, Heat-Treated)

When sourced as a round bar or rod, Type 422 is typically delivered in the hardened and tempered condition (often conforming to ASTM A565 Grade 616).

• Tensile Strength: $\ge 140,000 \text{ psi}$ ($965 \text{ MPa}$)

• Yield Strength (0.2% Offset): $\ge 110,000 \text{ psi}$ ($760 \text{ MPa}$)

• Elongation (in 2"): $\ge 15\%$

• Typical Hardness Range: 290 to 350 HBW (31 to 38 HRC)

3. Microstructure and Processing Realities

Heat Treatment Requirements

To develop its target mechanical properties, Type 422 undergoes a strict thermal profile:

1. Austenitizing: Heated to $1900^\circ\text{F} - 1950^\circ\text{F}$ ($1038^\circ\text{C} - 1066^\circ\text{C}$) followed by an oil or air quench to form a fully martensitic matrix.

2. Tempering: Must be tempered at a minimum of $1100^\circ\text{F}$ ($593^\circ\text{C}$) to guarantee high-temperature stability. Because of secondary hardening effects driven by the tungsten and vanadium additions, tempering at these high ranges precipitates a fine dispersion of spheroidized carbides (as visualized above) which locks the matrix against high-temperature creep.

Machinability & Fabrication

• Machining: Rated at approximately 40-45% of AISI 1212. Because it is highly alloyed, it produces tough, stringy chips and exhibits rapid work hardening. Rigid setups, heavy sulfurized cutting oils, and sharp carbide tooling are mandatory.

• Welding: Due to high carbon and alloy levels, Type 422 is highly prone to cold cracking. It requires strict preheating to $400^\circ\text{F} - 600^\circ\text{F}$ ($204^\circ\text{C} - 316^\circ\text{C}$), constant interpass control, and a mandatory immediate post-weld heat treatment (PWHT) / stress relief to temper the brittle heat-affected zone (HAZ).

4. Primary Procurement Specifications

If you are drafting purchase orders or validating mill test reports (MTRs) for 422 bars or rods, the material usually aligns with the following industrial baselines:

Typical Applications

Because of its unique blend of high thermal strength and corrosion resistance, AISI 422 bars are frequently machined into:

• Steam Turbine Components: High-pressure bucket blades, rotors, and shroud bolting.

• Aerospace Hardware: Valve components, structural aircraft fasteners, and gas turbine compressor wheels.

• Power Generation Equipment: High-temperature structural pins, boiler trim parts, and heavy-duty reaction vessels.