Method of heat treatment of additively manufactured low alloy steel / duplex stainless steel structures

Abstract

The application discloses a heat treatment method for additive manufacturing of low-alloy steel / dual-phase stainless steel structural parts, and is performed according to the following steps: step one: surface treatment is performed on a low-alloy steel base plate, and then low-alloy steel and dual-phase stainless steel are sequentially added on the low-alloy steel base plate to obtain a low-alloy steel / dual-phase stainless steel structural part; step two: the low-alloy steel / dual-phase stainless steel structural part obtained through additive manufacturing in step one is placed into a box-type resistance furnace for heating; step three: after heating to a predetermined temperature, the low-alloy steel / dual-phase stainless steel structural part is kept at constant temperature for heat preservation; and step four: after the heat preservation is completed, the test piece is taken out and quenched for rapid cooling. The method improves the microstructure uniformity and mechanical properties of the low-alloy steel / dual-phase stainless steel composite structure.

Description

Technical Field

[0001] This invention belongs to the field of material heat treatment technology, specifically relating to a heat treatment method for additive manufacturing low alloy steel / duplex stainless steel structural parts. Background Technology

[0002] Heterogeneous materials or functionally graded materials can possess specific local properties through varying spatial chemical properties and microstructures to adapt to diverse and complex service environments. Bimetallic composite structures, composed of two different metals, combine the distinctly different properties (thermal, physical, and mechanical) of dissimilar metals. Low-alloy steel / duplex stainless steel bimetallic composite structures possess both the excellent corrosion resistance of duplex stainless steel and the low cost advantage of low-alloy steel. In practical applications, this can save costs and avoid waste. Compared to traditional rolling and casting methods, arc additive manufacturing technology can directly form complex-shaped parts based on the workpiece's three-dimensional data. Arc additive manufacturing technology using wire as raw material is highly efficient and low-cost, and can manufacture multiple materials in a specific sequence, making it a key technology for manufacturing heterogeneous material structures.

[0003] However, the direct energy deposition method of wire arc additive manufacturing of bimetallic composite structures leads to strong microstructural anisotropy, residual stress at the interface, and deformation. Due to the thermal cycling and complex heat accumulation process in additive manufacturing, the microstructure of the resulting structures is highly complex, necessitating the control of microstructure and phase composition to achieve the desired performance. Heat treatment is an effective way to control the microstructure and mechanical properties of bimetallic composite structures, making the microstructure more uniform and significantly improving mechanical properties. While existing technologies have researched manufacturing processes for low-alloy steel / duplex stainless steel composite structures, research on heat treatment methods for composite structures is limited. Therefore, further improvements in the microstructure uniformity and mechanical properties of additively manufactured low-alloy steel / duplex stainless steel composite structures face challenges. Summary of the Invention

[0004] The purpose of this invention is to provide a heat treatment method for additive manufacturing of low alloy steel / duplex stainless steel structural parts, which improves the microstructure uniformity and mechanical properties of the low alloy steel / duplex stainless steel composite structure.

[0005] The technical solution adopted in this invention is a heat treatment method for additive manufacturing of low alloy steel / duplex stainless steel structural parts, which is carried out according to the following steps:

[0006] Step 1: Surface treatment is performed on the low alloy steel substrate, and then low alloy steel and duplex stainless steel are sequentially added on the low alloy steel substrate to obtain a low alloy steel / duplex stainless steel structural component.

[0007] Step 2: Place the low-alloy steel / duplex stainless steel structural parts obtained from the additive manufacturing in Step 1 into a box-type resistance furnace for heating;

[0008] Step 3: After heating to the predetermined temperature, keep the low alloy steel / duplex stainless steel structural components at a constant temperature.

[0009] Step 4: After the heat preservation is completed, remove the specimen and quench it for rapid cooling.

[0010] The invention is further characterized in that,

[0011] In step one, the specific process of surface treatment of the low alloy steel substrate is as follows: polish the low alloy steel substrate until the surface has a metallic luster, then place it in an ultrasonic vibrator containing anhydrous ethanol for cleaning to remove surface oil stains, and then let it dry.

[0012] In step one, the specific method for sequentially adding low-alloy steel and duplex stainless steel onto a low-alloy steel substrate to obtain a low-alloy steel / duplex stainless steel structural component is as follows: A cold metal transfer welding method is used. First, low-alloy steel is manufactured on the low-alloy steel substrate using ER50-6 welding wire. The process parameters are: welding current: 170A~180A, welding voltage: 18.6V~19V, welding speed: 0.20mm / min~0.25mm / min, welding radius: 6mm-8mm, and shielding gas: 80% Ar+ (volume fraction). A mixed gas with a volume fraction of 20% CO2, and the sum of the volume percentages of the above components is 100%; after the low alloy steel is manufactured, the cold metal transfer method is used to additively manufacture duplex stainless steel using ER2209 welding wire as raw material. The process parameters are: welding current: 130A~140A, welding voltage: 20V~21V, welding speed: 0.23mm / min~0.27mm / min, welding radius 6-8mm, and shielding gas: 100% Ar; the low alloy steel / duplex stainless steel composite structure is obtained by sequential deposition.

[0013] In step two, the heating temperature is 1060℃~1140℃, the heating rate is set to 200℃ / min~300℃ / min, and the heating rate is kept constant.

[0014] In step three, the heat preservation time is 1 hour.

[0015] In step four, the cooling method is water cooling, with a cooling rate of 300℃ / min to 400℃ / min. Water cooling is a rapid cooling treatment of low alloy steel / duplex stainless steel parts through an immersion etching method.

[0016] The beneficial effects of this invention are:

[0017] (1) This invention is a heat treatment method for regulating the microstructure and improving the mechanical properties of additively manufactured low-alloy steel / duplex stainless steel bimetallic composite structures. The low-alloy steel / duplex stainless steel parts are heated to the solution temperature and held for 1 hour to ensure more uniform heating. Immediately after the holding period, the parts are water-cooled to room temperature. Rapid cooling is achieved through water-cooled etching to prevent excessive austenite formation and the precipitation of harmful secondary phases such as σ-phase and carbides in the duplex stainless steel. This method improves the microstructure uniformity and mechanical properties of the low-alloy steel / duplex stainless steel composite structure.

[0018] (2) This invention provides a heat treatment method for additive manufacturing of low alloy steel / duplex stainless steel bimetallic composite structural parts. Compared with specimens produced by direct deposition and high-temperature tempering (500-650℃, holding for 2 hours), the reduction of area is improved, the microstructure inhomogeneity of the structural parts is reduced, and the mechanical properties of the structural parts are improved, resulting in significant optimization of the mechanical properties.

[0019] (3) The method of the present invention uses electric arc additive manufacturing process to manufacture low alloy steel / duplex stainless steel structural parts. Compared with traditional rolling, casting and other methods, additive manufacturing technology uses a layer-by-layer stacking method to manufacture structural parts, which has excellent metallurgical bonding, low cost and high efficiency, and has broad application prospects in the field of low alloy steel / duplex stainless steel bimetallic manufacturing. Attached Figure Description

[0020] Figure 1 This is a metallographic photograph of the interface of the low alloy steel / duplex stainless steel part after heat treatment at a heating temperature of 1100℃ and a holding time of 1h, as described in Example 1.

[0021] Figure 2 This is a metallographic photograph of the duplex stainless steel side of a low alloy steel / duplex stainless steel part after heat treatment at a heating temperature of 1100℃ and a holding time of 1h, as described in Example 1.

[0022] Figure 3 This is a metallographic photograph of the low-alloy steel side of the low-alloy steel / duplex stainless steel part after heat treatment at a heating temperature of 1100℃ and a holding time of 1h, as described in Example 1.

[0023] Figure 4 This is a comparison chart of the tensile properties of low alloy steel / duplex stainless steel parts before and after heat treatment in Example 1. Detailed Implementation

[0024] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0025] This invention provides a heat treatment method for additively manufactured low-alloy steel / duplex stainless steel structural parts, which is carried out according to the following steps:

[0026] Step 1: Surface treatment is performed on the low alloy steel substrate, and then low alloy steel and duplex stainless steel are sequentially added on the low alloy steel substrate to obtain a low alloy steel / duplex stainless steel structural component.

[0027] In step one, the specific process of surface treatment of the low alloy steel substrate is as follows: polish the low alloy steel substrate until the surface has a metallic luster, then place it in an ultrasonic vibrator containing anhydrous ethanol for cleaning to remove surface oil stains, and then let it dry.

[0028] In step one, the specific method for sequentially adding low-alloy steel and duplex stainless steel onto a low-alloy steel substrate to obtain a low-alloy steel / duplex stainless steel structural component is as follows: A cold metal transfer welding method is used. First, low-alloy steel is manufactured on the low-alloy steel substrate using ER50-6 welding wire. The process parameters are: welding current: 170A~180A, welding voltage: 18.6V~19V, welding speed: 0.20mm / min~0.25mm / min, welding radius: 6-8mm, and shielding gas: 80% Ar+ volume fraction. A mixed gas with a component of 20% CO2, and the sum of the volume percentages of the above components is 100%; after the low alloy steel is manufactured, the cold metal transfer method is used to additively manufacture duplex stainless steel using ER2209 welding wire as raw material. The process parameters are: welding current: 130A~140A, welding voltage: 20V~21V, welding speed: 0.23mm / min~0.27mm / min, welding radius: 6-8mm, and shielding gas: 100% Ar; a low alloy steel / duplex stainless steel composite structure is obtained by sequential deposition.

[0029] Step 2: Place the low-alloy steel / duplex stainless steel structural parts obtained from the additive manufacturing in Step 1 into a box-type resistance furnace for heating;

[0030] In step two, the heating temperature is 1060℃~1140℃, the heating rate is set to 200℃ / min~300℃ / min, and the heating rate is kept constant.

[0031] Step 3: After heating to the predetermined temperature, keep the low alloy steel / duplex stainless steel structural parts at a constant temperature for 1 hour.

[0032] Step 4: After the heat preservation is completed, remove the specimen and quench it for rapid cooling.

[0033] In step four, the cooling method is water cooling, with a cooling rate of 300℃ / min to 400℃ / min. Water cooling is a rapid cooling treatment of low alloy steel / duplex stainless steel parts through an immersion etching method.

[0034] Example 1

[0035] A heat treatment method for additively manufactured low-alloy steel / duplex stainless steel structural parts, comprising the following steps:

[0036] Step 1: Surface treatment is performed on the low alloy steel substrate, and then low alloy steel and duplex stainless steel are sequentially added on the low alloy steel substrate to obtain a low alloy steel / duplex stainless steel structural component.

[0037] In step one, the specific process of surface treatment of the low alloy steel substrate is as follows: polish the low alloy steel substrate until the surface has a metallic luster, then place it in an ultrasonic vibrator containing anhydrous ethanol for cleaning to remove surface oil stains, and then let it dry.

[0038] In step one, the specific method for sequentially adding low-alloy steel and duplex stainless steel onto a low-alloy steel substrate to obtain a low-alloy steel / duplex stainless steel structural component is as follows: A cold metal transfer welding method is used. First, low-alloy steel is manufactured on the low-alloy steel substrate using ER50-6 welding wire. The process parameters are: welding current: 170A~180A, welding voltage: 18.6V~19V, welding speed: 0.20mm / min~0.25mm / min, welding radius: 6mm-8mm, and shielding gas: 80% Ar+ (volume fraction). A mixed gas with a volume fraction of 20% CO2, and the sum of the volume percentages of the above components is 100%; after the low alloy steel is manufactured, the cold metal transfer method is used to additively manufacture duplex stainless steel using ER2209 welding wire as raw material. The process parameters are: welding current: 130A~140A, welding voltage: 20V~21V, welding speed: 0.23mm / min~0.27mm / min, welding radius: 6-8mm, and shielding gas: 100% Ar; the low alloy steel / duplex stainless steel composite structure is obtained by sequential deposition.

[0039] Step 2: Place the low-alloy steel / duplex stainless steel structural parts obtained from the additive manufacturing in Step 1 into a box-type resistance furnace for heating;

[0040] In step two, the heating temperature is 1100℃, the heating rate is set to 300℃ / min, and the heating rate is kept constant.

[0041] Step 3: After heating to the predetermined temperature, keep the low alloy steel / duplex stainless steel structural parts at a constant temperature for 1 hour.

[0042] Step 4: After the heat preservation is completed, remove the specimen and quench it for rapid cooling.

[0043] In step four, the cooling method is water cooling, and the cooling rate is 400℃ / min. Water cooling is a rapid cooling treatment of low alloy steel / duplex stainless steel parts by immersion etching.

[0044] from Figure 1 As can be seen, there is a clear interface in the additively manufactured bimetallic composite structure;

[0045] from Figure 2 As can be seen from the data, after heat treatment, one side of the duplex stainless steel has a ferrite and austenite duplex structure with a more uniform distribution and a ratio of the two phases close to 1:1.

[0046] from Figure 3 As can be seen from the data, the microstructure of the low alloy steel after heat treatment consists of side strip ferrite and acicular ferrite, and its crystal structure is characterized by columnar crystals with uniform grain size.

[0047] Compared to specimens in the deposited state and those treated with tempering (heating temperature 500–650℃, holding time 2h), specimens heated to 1100℃ and held for 1h exhibited fine banded austenite uniformly distributed within a ferrite matrix on the duplex stainless steel side, resulting in a more homogeneous microstructure. On the low-alloy steel side, heat treatment resulted in the formation of a series of microstructures, including ferrite and pearlite, and demonstrated very high strength and hardness. The fracture surface shifted from the low-alloy steel side to the duplex stainless steel side through heat treatment, improving tensile strength and elongation at break, thus optimizing mechanical properties. Figure 4 As can be seen, after heat treatment, the yield strength is approximately 500 MPa and the tensile strength is approximately 720 MPa, representing increases of 32% and 39% respectively compared to the deposited state sample. Heat treatment significantly improves the mechanical properties of the composite structure. This method enhances the microstructure uniformity and mechanical properties of the low-alloy steel / duplex stainless steel composite structure.

[0048] Example 2

[0049] A heat treatment method for additively manufactured low-alloy steel / duplex stainless steel structural parts, comprising the following steps:

[0050] Step 1: Surface treatment is performed on the low alloy steel substrate, and then low alloy steel and duplex stainless steel are sequentially added on the low alloy steel substrate to obtain a low alloy steel / duplex stainless steel structural component.

[0051] In step one, the specific process of surface treatment of the low alloy steel substrate is as follows: polish the low alloy steel substrate until the surface has a metallic luster, then place it in an ultrasonic vibrator containing anhydrous ethanol for cleaning to remove surface oil stains, and then let it dry.

[0052] In step one, the specific method for sequentially adding low-alloy steel and duplex stainless steel onto a low-alloy steel substrate to obtain a low-alloy steel / duplex stainless steel structural component is as follows: A cold metal transfer welding method is used. First, low-alloy steel is manufactured on the low-alloy steel substrate using ER50-6 welding wire. The process parameters are: welding current: 170A~180A, welding voltage: 18.6V~19V, welding speed: 0.20mm / min~0.25mm / min, welding radius: 6mm-8mm, and shielding gas: 80% Ar+ (volume fraction). A mixed gas with a volume fraction of 20% CO2, and the sum of the volume percentages of the above components is 100%; after the low alloy steel is manufactured, the cold metal transfer method is used to additively manufacture duplex stainless steel using ER2209 welding wire as raw material. The process parameters are: welding current: 130A~140A, welding voltage: 20V~21V, welding speed: 0.23mm / min~0.27mm / min, welding radius: 6-8mm, and shielding gas: 100% Ar; the low alloy steel / duplex stainless steel composite structure is obtained by sequential deposition.

[0053] Step 2: Place the low-alloy steel / duplex stainless steel structural parts obtained from the additive manufacturing in Step 1 into a box-type resistance furnace for heating;

[0054] In step two, the heating temperature is 1060℃, the heating rate is set to 300℃ / min, and the heating rate is kept constant.

[0055] Step 3: After heating to the predetermined temperature, keep the low alloy steel / duplex stainless steel structural parts at a constant temperature for 1 hour.

[0056] Step 4: After the heat preservation is completed, remove the specimen and quench it for rapid cooling.

[0057] In step four, the cooling method is water cooling, and the cooling rate is 400℃ / min. Water cooling is a rapid cooling treatment of low alloy steel / duplex stainless steel parts by immersion etching.

[0058] Example 3

[0059] The heat treatment method for additively manufactured low-alloy steel / duplex stainless steel structural parts shall be carried out according to the following steps:

[0060] Step 1: Surface treatment is performed on the low alloy steel substrate, and then low alloy steel and duplex stainless steel are sequentially added on the low alloy steel substrate to obtain a low alloy steel / duplex stainless steel structural component.

[0061] In step one, the specific process of surface treatment of the low alloy steel substrate is as follows: polish the low alloy steel substrate until the surface has a metallic luster, then place it in an ultrasonic vibrator containing anhydrous ethanol for cleaning to remove surface oil stains, and then let it dry.

[0062] In step one, the specific method for sequentially adding low-alloy steel and duplex stainless steel onto a low-alloy steel substrate to obtain a low-alloy steel / duplex stainless steel structural component is as follows: A cold metal transfer welding method is used. First, low-alloy steel is manufactured on the low-alloy steel substrate using ER50-6 welding wire. The process parameters are: welding current: 170A~180A, welding voltage: 18.6V~19V, welding speed: 0.20mm / min~0.25mm / min, welding radius: 6mm-8mm, and shielding gas: 80% Ar+ (volume fraction). A mixed gas with a volume fraction of 20% CO2, and the sum of the volume percentages of the above components is 100%; after the low alloy steel is manufactured, the cold metal transfer method is used to additively manufacture duplex stainless steel using ER2209 welding wire as raw material. The process parameters are: welding current: 130A~140A, welding voltage: 20V~21V, welding speed: 0.23mm / min~0.27mm / min, welding radius: 6-8mm, and shielding gas: 100% Ar; the low alloy steel / duplex stainless steel composite structure is obtained by sequential deposition.

[0063] Step 2: Place the low-alloy steel / duplex stainless steel structural parts obtained from the additive manufacturing in Step 1 into a box-type resistance furnace for heating;

[0064] In step two, the heating temperature is 1140℃, the heating rate is set to 300℃ / min, and the heating rate is kept constant.

[0065] Step 3: After heating to the predetermined temperature, keep the low alloy steel / duplex stainless steel structural parts at a constant temperature for 1 hour.

[0066] Step 4: After the heat preservation is completed, remove the specimen and quench it for rapid cooling.

[0067] In step four, the cooling method is water cooling, and the cooling rate is 400℃ / min. Water cooling is a rapid cooling treatment of low alloy steel / duplex stainless steel parts by immersion etching.

[0068] Example 4

[0069] The heat treatment method for additively manufactured low-alloy steel / duplex stainless steel structural parts shall be carried out according to the following steps:

[0070] Step 1: Surface treatment is performed on the low alloy steel substrate, and then low alloy steel and duplex stainless steel are sequentially added on the low alloy steel substrate to obtain a low alloy steel / duplex stainless steel structural component.

[0071] In step one, the specific process of surface treatment of the low alloy steel substrate is as follows: polish the low alloy steel substrate until the surface has a metallic luster, then place it in an ultrasonic vibrator containing anhydrous ethanol for cleaning to remove surface oil stains, and then let it dry.

[0072] In step one, the specific method for sequentially adding low-alloy steel and duplex stainless steel onto a low-alloy steel substrate to obtain a low-alloy steel / duplex stainless steel structural component is as follows: A cold metal transfer welding method is used. First, low-alloy steel is manufactured on the low-alloy steel substrate using ER50-6 welding wire. The process parameters are: welding current: 170A~180A, welding voltage: 18.6V~19V, welding speed: 0.20mm / min~0.25mm / min, welding radius: 6mm-8mm, and shielding gas: 80% Ar+ (volume fraction). A mixed gas with a volume fraction of 20% CO2, and the sum of the volume percentages of the above components is 100%; after the low alloy steel is manufactured, the cold metal transfer method is used to additively manufacture duplex stainless steel using ER2209 welding wire as raw material. The process parameters are: welding current: 130A~140A, welding voltage: 20V~21V, welding speed: 0.23mm / min~0.27mm / min, welding radius: 6-8mm, and shielding gas: 100% Ar; the low alloy steel / duplex stainless steel composite structure is obtained by sequential deposition.

[0073] Step 2: Place the low-alloy steel / duplex stainless steel structural parts obtained from the additive manufacturing in Step 1 into a box-type resistance furnace for heating;

[0074] In step two, the heating temperature is 1080℃, the heating rate is set to 260℃ / min, and the heating rate is kept constant.

[0075] Step 3: After heating to the predetermined temperature, keep the low alloy steel / duplex stainless steel structural parts at a constant temperature for 1 hour.

[0076] Step 4: After the heat preservation is completed, remove the specimen and quench it for rapid cooling.

[0077] In step four, the cooling method is water cooling, and the cooling rate is 350℃ / min. Water cooling is a rapid cooling treatment of low alloy steel / duplex stainless steel parts by immersion etching.

[0078] Example 5

[0079] The heat treatment method for additively manufactured low-alloy steel / duplex stainless steel structural parts shall be carried out according to the following steps:

[0080] Step 1: Surface treatment is performed on the low alloy steel substrate, and then low alloy steel and duplex stainless steel are sequentially added on the low alloy steel substrate to obtain a low alloy steel / duplex stainless steel structural component.

[0081] In step one, the specific process of surface treatment of the low alloy steel substrate is as follows: polish the low alloy steel substrate until the surface has a metallic luster, then place it in an ultrasonic vibrator containing anhydrous ethanol for cleaning to remove surface oil stains, and then let it dry.

[0082] In step one, the specific method for sequentially adding low-alloy steel and duplex stainless steel onto a low-alloy steel substrate to obtain a low-alloy steel / duplex stainless steel structural component is as follows: A cold metal transfer welding method is used. First, low-alloy steel is manufactured on the low-alloy steel substrate using ER50-6 welding wire. The process parameters are: welding current: 170A~180A, welding voltage: 18.6V~19V, welding speed: 0.20mm / min~0.25mm / min, welding radius: 6mm-8mm, and shielding gas: 80% Ar+ (volume fraction). A mixed gas with a volume fraction of 20% CO2, and the sum of the volume percentages of the above components is 100%; after the low alloy steel is manufactured, the cold metal transfer method is used to additively manufacture duplex stainless steel using ER2209 welding wire as raw material. The process parameters are: welding current: 130A~140A, welding voltage: 20V~21V, welding speed: 0.23mm / min~0.27mm / min, welding radius: 6-8mm, and shielding gas: 100% Ar; the low alloy steel / duplex stainless steel composite structure is obtained by sequential deposition.

[0083] Step 2: Place the low-alloy steel / duplex stainless steel structural parts obtained from the additive manufacturing in Step 1 into a box-type resistance furnace for heating;

[0084] In step two, the heating temperature is 1120℃, the heating rate is set to 200℃ / min, and the heating rate is kept constant.

[0085] Step 3: After heating to the predetermined temperature, keep the low alloy steel / duplex stainless steel structural parts at a constant temperature for 1 hour.

[0086] Step 4: After the heat preservation is completed, remove the specimen and quench it for rapid cooling.

[0087] In step four, the cooling method is water cooling, and the cooling rate is 300℃ / min. Water cooling is a rapid cooling treatment of low alloy steel / duplex stainless steel parts by immersion etching.

[0088] The low-alloy steel substrate in Examples 1-5 can be Q345.

Claims

1. A heat treatment method for additively manufactured low-alloy steel / duplex stainless steel structural parts, characterized in that, Follow these steps: Step 1: Surface treatment is performed on the low alloy steel substrate, and then low alloy steel and duplex stainless steel are sequentially added on the low alloy steel substrate to obtain a low alloy steel / duplex stainless steel structural component. In step one, the specific method for sequentially adding low-alloy steel and duplex stainless steel onto a low-alloy steel substrate to obtain a low-alloy steel / duplex stainless steel structural component is as follows: A cold metal transfer welding method is used. First, low-alloy steel is manufactured on the low-alloy steel substrate using ER50-6 welding wire. The process parameters are: welding current: 170A~180A, welding voltage: 18.6V~19V, welding speed: 0.20mm / min~0.25mm / min, welding radius: 6mm-8mm, and shielding gas: 80% Ar by volume. A mixed gas with a volume fraction of 20% CO2, the sum of the volume percentages of the above components being 100%; after the low alloy steel is manufactured, the cold metal transfer method is used to additively manufacture duplex stainless steel using ER2209 welding wire as raw material. The process parameters are: welding current: 130A~140A, welding voltage: 20V~21V, welding speed: 0.23mm / min~0.27mm / min, welding radius 6-8mm, shielding gas: 100% Ar; a low alloy steel / duplex stainless steel composite structure is obtained by sequential deposition; Step 2: Place the low-alloy steel / duplex stainless steel structural parts obtained from the additive manufacturing in Step 1 into a box-type resistance furnace for heating; In step two, the heating temperature is 1060℃~1140℃, the heating rate is set to 200℃ / min~300℃ / min, and the heating rate is kept constant. Step 3: After heating to the predetermined temperature, keep the low alloy steel / duplex stainless steel structural parts at a constant temperature; in Step 3, the holding time is 1 hour. Step 4: After the heat preservation is completed, remove the specimen, quench it, and cool it rapidly. In step four, the cooling method is water cooling, and the cooling rate is 300℃ / min ~ 400℃ / min.

2. The heat treatment method for additive manufacturing low-alloy steel / duplex stainless steel structural parts according to claim 1, characterized in that, In step one, the specific process of surface treatment of the low alloy steel substrate is as follows: polish the low alloy steel substrate until the surface has a metallic luster, then place it in an ultrasonic vibrator containing anhydrous ethanol for cleaning to remove surface oil stains, and then let it dry.

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