Heat treatment process of Inconel 718 board

- Aug 24, 2019-

(1). Warm up

The workpiece must be surface cleaned before and during heating to keep the surface clean. If the heated environment contains sulfur, phosphorus, lead or other low melting point metals, the Inconel 718 alloy will become brittle. Impurities come from painting, chalk, lubricating oil, water, fuel, etc. The sulfur content of the fuel should be low, such as the impurity content of liquefied gas and natural gas should be less than 0.1%, the sulfur content of city gas should be less than 0.25g / m3, and the sulfur content of petroleum gas should be less than 0.5%.

The heated electric furnace preferably has a relatively precise temperature control capability, the furnace gas must be neutral or weakly alkaline, and the composition of the furnace gas should be prevented from fluctuating in terms of oxidation and reduction properties.

(2). Heat treatment

A suitable hot working temperature for the Inconel 718 alloy is 1120-900 °C. The cooling method can be water quenching or other rapid cooling methods. After heat treatment, it should be annealed in time to ensure the best performance. During hot working, the material should be heated to the upper limit of the processing temperature. In order to ensure plasticity during processing, when the amount of deformation reaches 20%, the final processing temperature should not be lower than 960 °C.

(3). Cold work

Cold working should be carried out after solution treatment. Inconel718 has a higher work hardening rate than austenitic stainless steel. Therefore, the processing equipment should be adjusted accordingly and an intermediate annealing process should be performed during cold working.

(4). Heat treatment

Different solution treatments and aging treatments will result in different material properties. Due to the low diffusion rate of the gamma "phase, Inconel 718 alloy achieves optimum mechanical properties through extended aging treatment.

(5). polishing

The oxide near the Inconel718 workpiece weld is more difficult to remove than stainless steel. Need to be sanded with a fine abrasive belt. Prior to pickling with a mixed acid of nitric acid and hydrofluoric acid, sandpaper should also be used to remove the oxide or salt bath pre-preparation. deal with.

(6). machining

The processing of Inconel 718 is carried out after solution treatment. Inconel 718 is suitable for low surface cutting speeds, unlike austenitic stainless steels, given the work hardenability of the material.

(7). welding

The precipitation hardened Inconel 718 alloy is ideal for welding and will not break after welding. Adhesion, ease of processing and high strength are several advantages of this material.

Inconel718 is suitable for arc welding, plasma welding, etc. Before welding, the surface of the material should be clean, free of oil, no powder, etc. The polished metal should be polished within 25 mm around the weld.

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