阅读说明：本技术 一种消除高温合金inconel783螺栓中β相内laves相的热处理方法 (Heat treatment method for eliminating beta phase inner laves phase in high-temperature alloy inconel783 bolt ) 是由 杜晓东 陶思友 巫振伟 刘润飞 王赛龙 于 2020-08-11 设计创作，主要内容包括：本发明公开了一种消除高温合金inconel783螺栓中β相内laves相的热处理方法,是对β相内存在laves相的inconel783螺栓试样依次进行固溶处理、β时效处理和γ’时效处理。通过本发明的热处理方法,可使laves相中的Nb固溶进奥氏体基体,细化β相中的Laves相,使大量针状的Laves相转变成细小的棒状Laves相,甚至使Laves相完全消除,使得材料的塑性韧性恢复；通过本发明的热处理方法,可以细化β相的尺寸,恢复材料的强度及塑韧性。(The invention discloses a heat treatment method for eliminating a laves phase in a beta phase in a high-temperature alloy inconel783 bolt, which is to sequentially perform solid solution treatment, beta aging treatment and gamma' aging treatment on an inconel783 bolt sample with the laves phase in the beta phase. By the heat treatment method, Nb in the Laves phase can be dissolved into an austenite matrix in a solid way, the Laves phase in the beta phase is refined, a large amount of needle-shaped Laves phases are converted into fine rod-shaped Laves phases, and even the Laves phases are completely eliminated, so that the plastic toughness of the material is recovered; the heat treatment method can refine the size of the beta phase and recover the strength and the plasticity and toughness of the material.)

1. A heat treatment method for eliminating a laves phase in a beta phase in a high-temperature alloy inconel783 bolt is characterized by comprising the following steps of:

and carrying out heat treatment on the inconel783 bolt sample with the laves phase in the beta phase, wherein the heat treatment sequentially comprises solid solution treatment, beta aging treatment and gamma' aging treatment.

2. The heat treatment method according to claim 1, characterized in that:

the solid solution treatment is to keep the temperature of an inconel783 bolt sample with laves phase in the beta phase at 1110-1150 ℃ for 1h, and air-cool the bolt sample to room temperature.

3. The heat treatment method according to claim 1, characterized in that:

and the beta aging treatment is to insulate the inconel783 bolt subjected to the solution treatment at 840 ℃ for 6h and cool the bolt to room temperature in air.

4. The heat treatment method according to claim 1, characterized in that:

and the gamma' aging treatment is to insulate the inconel783 bolt subjected to the beta aging treatment at 720 ℃ for 8h, cool the bolt to 630 ℃ along with the furnace, insulate the bolt for 8h, and cool the bolt to room temperature.

5. The heat treatment method according to claim 2, characterized in that:

the heating rate in the solution treatment is less than or equal to 5 ℃/min.

6. The heat treatment method according to claim 3, characterized in that:

the heating rate in beta aging treatment is less than or equal to 5 ℃/min.

7. The heat treatment method according to claim 4, characterized in that:

the heating rate of the gamma 'aging treatment is less than or equal to 5 ℃/min, and the gamma' aging treatment is carried out along with furnace cooling at the cooling rate of 55 ℃/h.

Technical Field

The invention belongs to the technical field of alloy heat treatment, and particularly relates to a heat treatment method for eliminating beta-phase inner laves phase in a high-temperature alloy inconel783 bolt.

Background

In order to meet the requirements of the development of the times, the requirements of the power industry on energy conservation and emission reduction are continuously improved, and a conventional parameter thermal generator set is accelerating to be converted into a high-parameter supercritical generator set. The low-expansion high-temperature alloy inconel783 introduced from the aerospace field has wide application in supercritical units. inconel783 is a low expansion coefficient high temperature alloy based on Fe-Ni-Co, and because the Al content (more than or equal to 5 percent) of the alloy is far higher than that of other traditional low expansion coefficient high temperature alloys, the alloy can precipitate dispersed gamma' phase and Ni-Al type beta phase on a gamma austenite matrix, thereby improving the Stress Accelerated Grain Boundary Oxidation (SAGBO) resistance and the endurance life of the alloy. At present, the three-phase (gamma-gamma' -beta) alloy is widely applied to connecting bolts of a main valve, a high-speed regulating valve and a steam guide pipe flange of a supercritical unit, but the hardness of the bolts is found to exceed the normal level in the conventional maintenance of the unit, a Laves phase is found to exist in the beta phase, a large number of needle-shaped Laves phases occupy the inside of the beta phase, the original structure of the beta phase is damaged, the plasticity and toughness of the bolts are reduced, and potential safety hazards are formed on the safe operation of equipment.

Disclosure of Invention

The invention provides a heat treatment method for eliminating Laves phases in beta phases in high-temperature alloy inconel783 bolts, aiming at the problems that the Laves phases exist in the beta phases in the use process of the prior inconel783 bolts, the original structures of the beta phases are damaged, the ductility and toughness are reduced, and the use safety of the bolts is influenced.

The invention discloses a heat treatment method for eliminating a beta phase inner laves phase in a high-temperature alloy inconel783 bolt, which sequentially comprises the following steps of solution treatment, beta aging treatment and gamma' aging treatment:

step 1: carrying out solution treatment on an inconel783 bolt sample with laves phase in beta phase, preserving heat for 1h at 1110-1150 ℃, and cooling in air to room temperature;

step 2: carrying out beta aging treatment on the inconel783 bolt treated in the step 1, preserving the heat at 840 ℃ for 6h, and air-cooling to room temperature;

and step 3: and (3) carrying out gamma' aging treatment on the inconel783 bolt treated in the step (2), preserving heat for 8h at 720 ℃, cooling to 630 ℃ along with a furnace, preserving heat for 8h, and cooling to room temperature in air.

Preferably, the heating rate in the step 1 is less than or equal to 5 ℃/min.

Preferably, the heating rate in the step 2 is less than or equal to 5 ℃/min.

Preferably, the temperature rising rate in the step 3 is less than or equal to 5 ℃/min, and the furnace is cooled at the temperature falling rate of 55 ℃/h.

Preferably, the test sample is a 660MW supercritical unit bolt taken from 5 years of service, a laves phase exists in a beta phase in the bolt, and the bolt is made of inconel 783. The laves phase is precipitated from the beta phase of the high-temperature alloy incol783 bolt in the using process.

The invention has the beneficial effects that:

1. by the heat treatment method, Nb in the Laves phase can be dissolved into an austenite matrix in a solid solution mode, the Laves phase in the beta phase is refined, a large number of needle-shaped Laves phases are converted into fine rod-shaped Laves phases, and even the Laves phases are completely eliminated, so that the plastic toughness of the material is recovered.

2. The heat treatment method can refine the size of the beta phase and recover the strength and the plasticity and toughness of the material.

Drawings

Fig. 1 is the beta phase of an inconel783 bolt in service for 5 years without heat treatment.

Figure 2 is the beta phase of inconel783 bolt heat treated in example 5 for 5 years service.

Fig. 3 shows the tension fracture of the non-heat treated inconel783 bolt.

FIG. 4 is an inconel783 bolt tensile fracture heat treated in example 5.

Detailed Description

The invention will be described in further detail below with reference to the drawings and examples of the specification.

Test materials, reagents and the like used in the following examples are commercially available unless otherwise specified.