IRON-BASED SUPERALLOY FOR HIGH TEMPERATURE 700 C WITH COHERENT PRECIPITATION OF CUBOIDAL B2 NANOPARTICLES

Abstract

An iron-based superalloy for high temperature 700° C. with coherent precipitation of cuboidal B2 nanoparticles, belongs to the field of heat-resistant stainless steel, including Fe, Cr, Ni, Al, Mo, W, Zr, B elements. C, Si, Mn, S, P, O, N are impurity elements. The weight percent (wt. %) of its alloy composition is Cr: 10.0˜12.0, Ni: 13.0˜15.0, Al: 6.0˜7.0, Mo: 2.0˜3.0, W: 0.3˜0.7, Zr: 0.03˜0.05, B: 0.004˜0.007, C≤0.02, Si≤0.20, Mn≤0.20, S≤0.01, P≤0.02, O≤0.005, N≤0.02, Fe: balance; and the atomic percent ratio of Zr/B is 1:1, the atomic percent ratio of Cr/(Mo+W) is 8:1, and the atomic percent ratio of Mo/W is 8:1. The coherent precipitation of cuboidal B2 nanoparticles in ferritic matrix through the alloy composition design.

Claims

1. An iron-based superalloy for high temperature 700° C. with coherent precipitation of cuboidal B2 nanoparticles, wherein the iron-based superalloy for high temperature of 700° C. includes Fe, Cr, Ni, Al, Mo, W, Zr, B elements, C, Si, Mn, S, P, O, N are impurity elements, and weight percent (wt. %) of alloy composition are Cr: 10.0˜12.0, Ni: 13.0˜15.0, Al: 6.0˜7.0, Mo: 2.0˜3.0, W: 0.3˜0.7, Zr: 0.03˜0.05, B: 0.004˜0.007, C≤0.02, Si≤0.20, Mn≤0.20, S≤0.01, P≤0.02, O≤0.005, N≤0.02, Fe: balance; and atomic percent ratio of Zr/B is 1:1; atomic percent ratio of Cr/(Mo+W) is 8:1; and atomic percent ratio of Mo/W is 8:1; wherein the iron-based superalloy has a specific microstructure: cuboidal B2 nanoparticles coherent precipitated in BCC ferritic matrix, which makes the iron-based superalloy exhibit good high-temperature microstructural stability and high strength at high temperature of 700° C.

2. (canceled)

Description

BRIEF DESCRIPTION OF DRAWINGS

[0015] The Figure is the TEM image of Fe-10.92Cr-13.87Ni-6.38A1-2.24Mo-0.54W-0.042Zr-0.005B (wt. %) alloy prepared in Example 1, showing coherent precipitation of cuboidal B2 nanoparticles in a ferrite matrix.

DETAILED DESCRIPTION

[0016] The specific implementation of the invention is described in detail below in combination with technical solutions.

EXAMPLE 1 Fe-10.92Cr-13.87Ni-6.38Al-2.24Mo-0.54W-0.042Zr-0.005B (wt. %) Alloy

[0017] Step 1: Preparation of Alloy

[0018] According to the mass percentage, the ingredients were prepared using high purity metal. The 15 g of the mixture was placed in the water-cooled copper crucible of the arc melting furnace and melted under the protection of argon atmosphere using the non-self-consuming arc melting method. And the ingots were so repeatedly melted at least five times to obtain alloy ingots of uniform composition. Then the uniformly melted alloy ingots were melted and the melt is drawn into the cylindrical copper model cavity using the copper mold suction casting process to obtain rods with a diameter of 6 mm. The alloy bars were then homogenized at 1200° C. for 2 h and finally aged at 700° C. for 24 h.

[0019] Step 2: The Microstructure and Mechanical Properties of the Alloy Were Tested

[0020] OM, SEM and XRD were used to examine the Microstructure of the alloy after aged treatment, and the results showed that the alloy matrix of the present invention is ferrite, and the cuboidal B2 nanoparticles are coherently precipitated in the ferrittic matrix, see shown in the Figure. Even after long-term aging, it still maintains good stability of BCC/B2 coherent precipitation; Room temperature hardness test was conducted using Vickers hardness tester HV=380 kgf.Math.mm.sup.−2. The mechanical properties of the alloy at room temperature and high temperature were measured using the UTM5504 electronic universal tensile tester: room temperature mechanical properties of the alloy were tensile strength σ.sub.b=1230 MPa; high temperature mechanical properties of the alloy at 700° C., yield strength σ.sub.s=253 MPa, tensile strength σ.sub.b=320 MPa.

EXAMPLE 2 Fe-10Cr-15Ni-6Al-3Mo-0.7W-0.03Zr-0.004B (wt. %) Alloy

[0021] Step 1: Preparation of Alloy

[0022] According to the mass percentage, the ingredients were prepared using high purity metal. The 15 g of the mixture was placed in the water-cooled copper crucible of the arc melting furnace and melted under the protection of argon atmosphere using the non-self-consuming arc melting method. And the ingots were so repeatedly melted at least five times to obtain alloy ingots of uniform composition. Then the uniformly melted alloy ingots were melted and the melt is drawn into the cylindrical copper model cavity using the copper mold suction casting process to obtain rods with a diameter of 6 mm. The alloy bars were then homogenized at 1200° C. for 2 h and finally aged at 700° C. for 0.5 h.

[0023] Step 2: The Microstructure and Mechanical Properties of the Alloy Were Tested

[0024] OM, SEM and XRD were used to examine the Microstructure of the alloy after aged treatment, and the results showed that the alloy matrix of the present invention is ferrite, and the cuboidal B2 nanoparticles are coherently precipitated in the ferrittic matrix, see shown in the Figure. Even after long-term aging, it still maintains good stability of BCC/B2 coherent precipitation; Room temperature hardness test was conducted using Vickers hardness tester HV=480 kgf.Math.mm.sup.−2. The mechanical properties of the alloy at room temperature and high temperature were measured using the UTM5504 electronic universal tensile tester: room temperature mechanical properties of the alloy were tensile strength σ.sub.b=1690 MPa; high temperature mechanical properties of the alloy at 700° C., yield strength σ.sub.s=265 MPa, tensile strength σ.sub.b=348 MPa.

EXAMPLE 3 Fe-12.0Cr-13.0Ni-7.0Al-2Mo-0.3W-0.05Zr-0.007B (wt. %) Alloy

[0025] Step 1: Preparation of Alloy

[0026] According to the mass percentage, the ingredients were prepared using high purity metal. The 15 g of the mixture was placed in the water-cooled copper crucible of the arc melting furnace and melted under the protection of argon atmosphere using the non-self-consuming arc melting method. And the ingots were so repeatedly melted at least five times to obtain alloy ingots of uniform composition. Then the uniformly melted alloy ingots were melted and the melt is drawn into the cylindrical copper model cavity using the copper mold suction casting process to obtain rods with a diameter of 6 mm. The alloy bars were then homogenized at 1200° C. for 2 h and finally aged at 700° C. for 48 h.

[0027] Step 2: The Microstructure and Mechanical Properties of the Alloy Were Tested

[0028] OM, SEM and XRD were used to examine the Microstructure of the alloy after aged treatment, and the results showed that the alloy matrix of the present invention is ferrite, and the cuboidal B2 nanoparticles are coherently precipitated in the ferrittic matrix, see shown in the Figure. Even after long-term aging, it still maintains good stability of BCC/B2 coherent precipitation; Room temperature hardness test was conducted using Vickers hardness tester HV=364 kgf.Math.mm.sup.−2. The mechanical properties of the alloy at room temperature and high temperature were measured using the UTM5504 electronic universal tensile tester: room temperature mechanical properties of the alloy were tensile strength σ.sub.b=1247 MPa; high temperature mechanical properties of the alloy at 700° C., yield strength σ.sub.s=237 MPa, tensile strength σ.sub.b=306 MPa.

[0029] The above described examples only express the way of implementation of the present invention, but they should not be understood as a limitation of the scope of the patent of the present invention, and it should be noted that for the technicians in the field, a number of deformations and improvements can be made without departing from the conception of the present invention, which all belong to the scope of protection of the present invention.