HastelloyX (GH3536) high temperature alloy metallographic structure
GH3536 alloy is a nickel-based high-temperature alloy with a high iron content that is mainly solid solution strengthened with chromium and molybdenum.
The effects of different heat treatment processes on the microstructure and mechanical properties of GH3536 alloy formed by selective laser melting were analyzed using OM, SEM and mechanical property testing. The results show that as the solid solution temperature increases, the grain size becomes larger, and the tensile strength gradually increases under high temperature conditions but decreases under room temperature conditions.
It has good anti-oxidation and corrosion resistance, has medium to medium durability and creep strength below 900 degree , and has good cold and hot processing formability and welding performance. It is suitable for manufacturing combustion chamber components and other high-temperature components of aero engines. It can be used under 900 degree for a long time and the short-term working temperature can reach 1080 degree . An alloy that can withstand certain stress at high temperatures of 600 to 1200 degree and has the ability to resist oxidation or corrosion.
When the solid solution temperature reaches 1120 degree , the tensile strength of the transverse test bar and the longitudinal test bar reach 816 and 731 MPa respectively under room temperature conditions; under high temperature conditions of 900 degree , they reach 189 and 204 MPa respectively. After aging treatment at 800 degree , fine carbides precipitate from the alloy matrix structure, producing a second phase strengthening effect and improving the strength. As the aging time increases, the carbides become denser, but the grain size hardly changes, which is reflected in the increase in room temperature tensile strength and elongation after fracture.
According to the matrix elements, it can be mainly divided into iron-based superalloys, nickel-based superalloys and cobalt-based superalloys. According to the preparation process, it can be divided into deformed high-temperature alloys, cast high-temperature alloys and powder metallurgy high-temperature alloys. According to the strengthening methods, there are solid solution strengthening, precipitation strengthening, oxide dispersion strengthening and fiber strengthening (see strengthening of metals). High-temperature alloys are mainly used to manufacture high-temperature components such as turbine blades, guide vanes, turbine discs, high-pressure compressor discs and combustion chambers for aviation, naval and industrial gas turbines; they are also used to manufacture aerospace vehicles, rocket engines, nuclear reactors, petrochemical equipment and Coal conversion and other energy conversion devices.
When the aging time reaches 20 h, the tensile strength of the transverse test bar and the longitudinal test bar under room temperature conditions reach 832 and 747 MPa respectively; the post-break elongation of the transverse test bar and the longitudinal test bar under high temperature conditions of 900 degree reaches 8. 5% and 21. 5%. Finally, the optimal heat treatment process for selective laser melting forming of GH3536 alloy is: solid solution (1120 degree × 1 h) + aging (800 degree × 20 h).
GH3536 chemical composition
Carbon C: Less than or equal to {{0}}.12 Chromium Cr: 21~25 Nickel Ni: 52.8~63.3 Aluminum AL: 1.8~1.7 Iron Fe: remainder Manganese Mn: Less than or equal to 1.57 Silicon Si: Less than or equal to 0.80 Phosphorus P: Less than or equal to 0.036 Sulfur S: Less than or equal to 0.04
GH3536 is a Ni-Cr-Fe-based solid solution strengthened deformed superalloy, with the international brand name Hastelloy-X. The alloy has excellent oxidation resistance and corrosion resistance as well as good welding properties and cold and hot workability. In my country's aviation industry, it has been used as aeroengine combustion chamber components, honeycomb structures, diffusers, tail nozzles and other hot end components. With the development of the times, aviation products continue to put forward new functional requirements, and the parts structure gradually becomes complex.
GH3536
UNS NO6002 HastelloyX (USA), NC22FeD (France), NiCr22FeMo (Germany), Nimonic PE13 (UK)
Traditional subtractive manufacturing methods often have many difficulties when processing parts with complex structures. Additive manufacturing technology solves the problem of difficult processing of complex components to a certain extent by virtue of its high degree of freedom manufacturing method. Selective laser melting is one of the main processes currently used for metal additive manufacturing. The powder bed process and high-energy micro-laser beam make it more advantageous than other processes in forming complex structures, part accuracy, surface quality, etc. Laser additive manufacturing has unique advantages for the manufacturing of nickel-based high-temperature alloys. It can not only shorten production time and reduce production costs, but also prioritize functional design.
GH3536 Metallographic structure:
The structure of this alloy in the solid solution state is an austenite matrix, with a small amount of TiN and M6C carbides.
In the actual production process, additive manufacturing products often require subsequent mechanical processing. However, during this process, processing weakness, tool sticking, and poor surface finish often occur. These defects are related to the forming principle of additive manufacturing. In order to solve such problems, such problems can be solved through a series of heat treatment process optimization. There are already corresponding heat treatment standards for cast GH3536 alloy. However, since selective laser melting involves a complex phase change process, it is necessary to explore the best heat treatment process plan based on selective laser melting technology.
