Blog Material Applications: Heat Resistant Alloy Profiles Part 2

Iron Chrome (Fe-Cr) Alloys. This group includes the grades HA, HC and HD.

Description

This family of stainless steel is often used in higher temperature but lower stress applications.

Properties – Why select this material

• Effective in load-bearing applications at temperatures up to 1200°F-1300°F/650°C-700°C).
• HA is used for components in low-stress applications.
• Resistant to high sulfur environments.

Some Typical Application Types

• Valves, flanges, and fittings
• Mineral processing
• Ore roasting furnace components
• Grate bars
• Salt pots

Iron Chrome Nickel (Fe-Cr-Ni) Alloys. This group includes the grades HE, HF, HH, HI, HK, HL.

Description

This family of stainless steel is often used in applications with higher temperature demands than the iron chrome family.

Properties – Why select this material

• HE provides moderate strength with corrosion resistance. Its typical service limit is 2000°F/1100°C.
• HF is effective in structural support environments. Its typical service limit is 1600°F/870°C.
• HH is produced in two sub-grades, Types 1 and 2. Typical service limits are 2000°F/1100°C. Type 1 is partly ferritic and has low creep strength and more high temperature ductility. Type 2 is purely austenitic and is stronger.
• HI is similar to HH Type 2, but contains more Cr and may therefore be used in oxidizing conditions with temperatures up to 2150°F/1180°C.
• HK alloys have good creep and rupture strength, and resistance to hot corrosion up to 2100°F/1150°C.
• HL has higher Cr than HK and is used in environments requiring higher resistance to sulfur and scaling.

Some Typical Application Types

• HE: Ore roasting and steel mill skids.
• HF: Petrochemical tube sheets, heat treat furnace fixtures, oil refinery tube supports.
• HH: Heat treat furnace components.
• HI: High temperature applications subject to oxidation.
• HK: Reformers for producing ammonia, methanol, and hydrogen. Ethylene pyrolysis coils, in tube supports and hangars, steam superheaters, and in heat treating fixtures.
• HL: Furnace skids and rolls, radiant heaters and rabble arms.

Iron Nickel Chrome (Fe-Ni-Cr) Alloys. This group includes four grades HN, HP, HT, and HU.

Description

This family of stainless steel all have stable austenitic structures and may be used at temperatures up to 2000°F – 2150°F/1100°C – 1180°C.

Properties – Why select this material

• HN provides good structural strength at high temperature.
• HP has high long term strength and good resistance to thermal cycling and carburization. With the addition of niobium its long term creep and rupture strength, ductility and weldability are increased.
• HT has high resistance to thermal shock and carburizing, and may be used in either oxidizing or reducing conditions up to 2100°F/1150°C and 2000°F/1100°C respectively.
• HU has the highest carburization and oxidation resistance of this group, but relatively low creep and rupture strength.

Some Typical Application Types

• Tube supports
• Hangars
• Heat treating fixtures and trays
• Furnace skids and rolls