Inconel 718 alloy is a precipitation-hardened nickel-chromium alloy containing niobium and molybdenum. It has high strength, good toughness and corrosion resistance in high and low temperature environment under 650℃.Its state [TJC STEEL.]may be solid solution treatment or precipitation hardened state.

 

Introduction for Inconel 718 Alloy:

 

Characteristics:

● Machinability

● High tensile strength, fatigue strength, creep strength and fracture strength at 700℃

● High oxidation resistance at 1000℃

● Stable chemical properties at low temperature

● Good welding performance

 

Application:

Due to its high temperature strength, excellent corrosion resistance and easy processing at 700℃, it can be widely used in various demanding occasions.● Liquid fuel rocket

● Low temperature engineering

● Acidic environment

 

Second-ranking Nuclear Engineering

Standards and Equivalent Materials with Inconel 718 Alloy:

GH4169, GH169 (China), NC19FeNb (France), NiCr19Fe19Nb5, Mo3(Germany), [TJC STEEL.]NA 51 (UK) Inconel718, UNS NO7718(USA) NiCr19Nb5Mo3(ISO)

 

Chemical Composition(%):

	镍Ni	-	铬Cr	-	铁Fe	-	碳C	-	锰Mn	-	硅Si	-	钼Mo	-	铜Cu	-	钴Co	-	铝Al	-	钛Ti	-	铌Nb	-	硼B	-	磷P	-	硫S
Min	50	-	17	-		-		-		-		-	2.8	-		-		-	0.2	-	0.65	-	4.75	-	0	-		-
Max	55	-	21	-	余量	-	0.08	-	0.35	-	0.35	-	3.3	-	0.3	-	1	-	0.8	-	1.15	-	5.5	-	0.006	-	0.01	-
																													0.01

 

Mechanical Property for Inconel 718 Alloy:

Density for Inconel 718 Alloy:

Rho = 8.24 g/cm3 density

Melting Temperature Range

The melting temperature ranges from 1260 ℃ to 1320℃

Processing and heat treatment editing

Inconel718 alloy is a difficult material in machining field.

 

Preheating:

Surfaces must be cleaned before and during heating to keep surfaces clean.Inconel718 alloy will become brittle if the heating environment contains sulfur, phosphorus, lead or other low melting point metals.Impurities come [TJC STEEL.]from marking paint, chalk, lubricating oil, water, fuel, etc.The sulfur content of fuel should be low, such as the impurity content of liquefied natural gas and natural gas should be less than 0.1%, the sulfur content of urban gas should be less than 0.25g/m3, the sulfur content of LPG should be less than 0.5% is ideal.

Electric furnace heating had better have more accurate temperature control ability, furnace gas must be neutral or weak alkaline, should avoid furnace gas composition in oxidation and reduction in fluctuation.

 

Hot Working:

The suitable hot working temperature of Inconel718 alloy is 1120-900℃. The cooling way can be water quenching or other rapid cooling way. After hot working, annealing should be timely to ensure the best performance.The material [TJC STEEL.]should be heated to the upper limit of the processing temperature during thermal processing. In order to ensure the plasticity during processing, the final processing temperature should not be lower than 960℃ when the deformation amount reaches 20%.

 

Cold Working

Cold working should be carried out after solid solution treatment, the working hardening rate of Inconel718 is higher than austenitic stainless steel, so the processing equipment should be adjusted accordingly, and there should be an intermediate annealing process in the cold working process.

 

Heat Treatment

Different solid solution treatment and aging treatment process can obtain different material properties.Due to the low diffusion rate of phase, the best mechanical properties of Inconel718 alloy can be obtained by aging treatment for a long time.

 

Polishing

The oxides near the welds of the Inconel718 workpieces are more difficult to remove than those of stainless steel, which need to be polished with a fine sand belt, and the oxides also need to be removed with sandpaper or pre-treated in a salt bath before pickling in a mixture of nitric and hydrofluoric acids.

 

Machining

The Inconel718 is machined after solution treatment, taking into account the material's work hardening properties. Unlike austenitic stainless steels, the Inconel718 is suitable for low surface cutting speeds.

 

Welding

Precipitation-hardened Inconel718 alloys are well suited for welding and have no post-weld cracking tendency.Weldability, machinability and high strength are the advantages of this material.

Inconel718 is suitable for arc welding, plasma welding, etc.Before welding, the surface of the material shall be clean, free from oil stains, chalk marks, etc., and the polished metal shall be exposed within 25mm around the weld.

 

Recommended Welding Materials for Inconel 718:

GTAW/GMAW

Nicrofer S 5219

W. - Nr. 2.4667

SG-NiCr19NbMoTi

AWS ERNiFeCr 5.14-2 A

BS 2901 Part 5: NA 51