Inconel 718 Hot Extruded Square Pipe

This makes Inconel 718 hot extruded square pipe from Jiangsu Ji Lai Da Nickel-Based Alloy Co., Ltd. (Ji lai da) the right choice when a square section must carry heavy structural load at 600–700 °C, not just resist corrosion. We produce it by hot extrusion through a square die — seamless, no welds, no corners that weren't formed as part of the original metal. One of the few China manufacturers offering this product, factory-direct with full MTC documentation.

Where 718 Differs from C276 and N08031

These three alloys solve different problems, and choosing the wrong one is expensive. C276 (16% Cr, 16% Mo, 4% W) is the gold standard for reducing-acid corrosion — hydrochloric, sulfuric, wet chlorine — but its yield strength tops out around 400 MPa and it softens quickly above 500 °C. N08031 (27% Cr, 6.5% Mo, 1.2% Cu) bridges oxidizing and reducing media brilliantly, yet it's also a solid-solution alloy with similar mechanical ceilings. Inconel 718 takes the opposite approach: 19% Cr and 3% Mo give moderate corrosion resistance, but the precipitation-hardening mechanism delivers triple the yield strength and maintains it to ~700 °C. If your square section sits inside a gas turbine hot duct, a rocket thrust structure, or a high-pressure reactor vessel where the temperature routinely exceeds 550 °C — C276 and N08031 will deform; Inconel 718 hot extruded square pipe will hold.

What Makes This Pipe Work

The one-piece extruded structure is critical for 718. This alloy is notoriously difficult to weld — it's susceptible to strain-age cracking in the heat-affected zone, and post-weld heat treatment must be precisely controlled to avoid losing the precipitation-hardened strength you specified the alloy for in the first place. A welded square tube in 718 has four longitudinal seams, each one a potential crack initiation site under thermal cycling. Our hot extrusion process forms Inconel 718 hot extruded square pipe as a single homogeneous body — no seams, no heat-affected zones, no weld inspection overhead. The grain flow follows the square contour continuously, distributing stress evenly at the corners where welded tubes concentrate it.

Equal-wall or unequal-wall profiles are both available. For aerospace duct structures where one face bolts to a hot component and the opposite face is exposed to cooler bypass air, an unequal-wall section puts metal exactly where the thermal and mechanical loads demand it — something you cannot achieve by welding flat plates together. Ji lai da supplies Inconel 718 hot extruded square pipe in solution-annealed condition (easier to machine, you age after final shaping) or fully aged condition (ready for installation at full strength). Custom cross-sections, custom heat treatment — one RFQ to Jiangsu Ji Lai Da Nickel-Based Alloy Co., Ltd.

Typical Service Environments

Inconel 718 hot extruded square pipe is specified where the combination of temperature, stress, and moderate corrosion rules out both stainless steel and corrosion-first nickel alloys:

● Gas turbine — hot duct structural frames, combustor liner supports, transition duct stiffeners at 600–700 °C
● Aerospace — engine pylon brackets, exhaust system structural housings, thrust reverser frames
● Oil & gas — HPHT downhole tool housings, subsea choke structural bodies
● Nuclear — reactor internals, control rod guide tube support structures
● Defense — missile airframe structural members, launch equipment frames

Q1: When should I pick 718 over C276 or N08031 for a square section?

A: When structural strength at elevated temperature is the primary driver. C276 and N08031 are stronger in acid corrosion — no question. But if your square section carries mechanical load at 550–700 °C, their ~400 MPa yield won't hold. Inconel 718 hot extruded square pipe delivers >1,000 MPa yield after aging. Choose the alloy that matches your first-priority failure mode.

Q2: Is welding 718 square tube a bad idea?

A: It's risky. 718 is prone to strain-age cracking in the weld heat-affected zone — the very act of welding can trigger premature precipitation that cracks the metal before you even age it. If you must weld, procedures must be tightly controlled and post-weld heat treatment is mandatory. With seamless extruded pipe from Ji lai da, you avoid the problem entirely.

Q3: Can you supply unequal-wall 718 square profiles?

A: Yes. Thick bottom wall for mounting or thermal contact, thin sides for weight reduction — whatever cross-section your design calls for. We custom-design the extrusion die for your profile.

Q4: How is your pricing?

A: Competitive. Inconel 718 hot extruded square pipe is rare — most mills don't offer it at all — so there aren't many reference prices. As a China manufacturer with our own extrusion line, we control the full chain and price without trading margins. Contact Jiangsu Ji Lai Da Nickel-Based Alloy Co., Ltd. and compare.

Q5: In what condition do you supply the pipe?

A: Solution-annealed (AMS 5662) for customers who want to machine or cold-form before aging, or fully precipitation-aged (AMS 5663) for immediate installation at full mechanical properties. Specify when ordering.