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Solution treatment + aging heat treatment process of 718 (Inconel 718) round bar

Inconel 718 is a nickel-based precipitation hardening high-temperature alloy, commonly used in high-temperature and high-stress environments such as aerospace, gas turbines, oil and gas, and nuclear industries. In order to obtain the best mechanical properties, high-temperature strength and corrosion resistance, a heat treatment process of solution treatment + aging treatment is usually used.

1. Solution treatment + aging heat treatment process of Inconel 718 round bar

① Solution treatment

▶Purpose:

To completely dissolve the metal elements (such as Nb, Ti, Al, Cr) in the alloy to form a uniform austenite matrix.

Eliminate processing stress and improve the plasticity and toughness of the material.

▶Process parameters:

Temperature: 980-1065℃

Holding time: 1-2 hours (depending on the rod diameter)

Cooling method: Air cooling (AC) or water cooling (WQ)

▶Recommendation:

1065℃

Solution treatment is suitable for applications requiring the highest toughness (such as aircraft engine components).

980℃

Solution treatment is suitable for applications requiring higher creep resistance (such as gas turbine components).

② Aging Treatment

▶Purpose:

Through precipitation strengthening (γ' and γ'' phase precipitation), the yield strength, creep resistance and high temperature stability of Inconel 718 are significantly improved.

▶Standard two-stage aging process (suitable for most applications)

Process temperature Holding time Cooling method

First stage aging 720-760℃ 8 hours Furnace cooling to 620℃

Second stage aging 620℃ 8 hours Air cooling (AC)

▶Analysis:

720-760℃:

Promote the precipitation of γ'' phase (Ni3Nb) and γ' phase (Ni3(Al,Ti)), improve the yield strength and creep resistance of the alloy.

620℃ Secondary aging:

Optimize the precipitation phase, increase the plasticity and fracture toughness of the material

2. Typical heat treatment process of Inconel 718 round bar

▶Process 1: Standard high-strength heat treatment (most common)

Solution treatment:

980-1065℃, 1-2 hours, air cooling (AC)

Aging treatment:

720℃ × 8 hours, then furnace cooling to 620℃ 620℃ × 8 hours, then air cooling (AC)

Applicable scenarios:

Applicable to high-temperature and high-strength applications such as aircraft engines, gas turbines, high-temperature fasteners, and nuclear industry.

▶Process 2: Optimized high-toughness heat treatment

Solution treatment: 1065℃ × 1-2 hours, air cooling (AC)

Aging treatment: 760℃ × 10 hours, then furnace cooling to 650℃ 650℃ × 10 hours, then air cooling (AC)

Applicable scenarios:

Applicable to low-temperature impact load applications, such as aerospace structural parts, supersonic aircraft parts, etc.

3.Performance after heat treatment (standard Inconel 718)

Performance index typical value

Yield strength (MPa) ≥ 1035

Tensile strength (MPa) ≥ 1375

Elongation (%) ≥ 12

Sectional shrinkage (%) ≥ 15

Hardness (HRC) 35-44

Operating temperature range -253℃ ~ 700℃

4. Important notes

① Solution cooling method: air cooling or water cooling, avoid too slow cooling, otherwise it will cause Laves phase precipitation and reduce the toughness of the material.

②Strict control of aging and heat preservation time: too long may cause grain growth and reduce fatigue resistance.

③Avoid excessively high temperature treatment: exceeding 980℃ may cause grain boundary embrittlement and reduce material performance.

④The diameter of the bar affects the heat treatment time: large-sized bars require longer heat preservation time to ensure uniform treatment.

⑤The solution treatment temperature of Inconel 718 round bar is 980-1065℃, and the aging treatment usually adopts a two-stage aging process of 720℃ × 8h + 620℃ × 8h.

⑥Different heat treatment schemes can optimize strength, toughness or high temperature resistance, and are suitable for different aerospace, petroleum, and nuclear industry applications.

⑦The heat treatment process requires precise control of cooling rate and aging time to obtain optimal organization and performance.

If your Inconel 718 round bar has specific size or special application requirements, the heat treatment scheme can be further optimized, welcome to contact us!