阅读说明：本技术 一种利用复合冲压获得异构金属薄板的方法 (Method for obtaining heterogeneous metal sheet by composite stamping ) 是由 周浩 黄家喜 陈雪飞 许梦凝 瞿振宇 肖礼容 李玉胜 曹阳 于 2020-05-26 设计创作，主要内容包括：本发明公开了一种利用复合冲压获得异构金属薄板的方法,包含：预处理、复杂模具冲压、平冲压和热处理四步工序,其具体步骤为,采用可形变诱导马氏体相变的材料作为原始材料,采用一对共轭的模具分别对预处理之后的奇数块原材料板材Ⅰ加热冲压获得样品Ⅱ和样品Ⅲ,将数块样品II和样品III按照表面凹凸形状共轭形成无间隙的Ⅲ-Ⅱ…Ⅲ叠层结构并进行加热平冲压,然后经热处理形成异质金属薄板。利用高韧相和高强相之间的背应力强化和背应力加工硬化,达到高强高韧的优异力学性能。可通过对原材料的选择,冲压模具的设计以及叠层方式的灵活性等调控,满足生产和应用中不同的强韧化需求。(The invention discloses a method for obtaining a heterogeneous metal sheet by composite stamping, which comprises the following steps: the method comprises the following steps of preprocessing, complex die stamping, flat stamping and heat treatment, wherein materials capable of inducing martensite phase transformation through deformation are used as raw materials, a pair of conjugated dies are used for heating and stamping an odd number of preprocessed raw material plates I respectively to obtain a sample II and a sample III, a plurality of samples II and samples III are conjugated according to the surface concave-convex shape to form a gapless III-II … III laminated structure, heating and flat stamping are carried out, and then the heterogeneous metal sheet is formed through heat treatment. The excellent mechanical properties of high strength and high toughness are achieved by utilizing the back stress strengthening and the back stress work hardening between the high toughness phase and the high strength phase. The method can meet different strengthening and toughening requirements in production and application by selecting raw materials, designing a stamping die, regulating and controlling the flexibility of a lamination mode and the like.)

1. A method for obtaining heterogeneous metal sheets by utilizing composite stamping is characterized in that materials capable of inducing martensite phase transformation through deformation are used as original materials, a pair of conjugated dies are used for heating and stamping an odd number of pretreated raw material plates I respectively to obtain a sample II and a sample III, the samples II and the sample III are conjugated according to the surface concave-convex shape to form a gapless III-II … III laminated structure, heating and flat stamping are carried out, and then the heterogeneous metal sheets are formed through heat treatment.

2. The method according to claim 1, characterized in that the degree of relief is adjusted according to different mechanical conditions; the hardness of the die material is positively correlated with that of the material to be punched, and the die hardness is 75-150 HV higher;

one of the conjugated molds is a convex mold a, and the other conjugated mold is a concave mold b; and (3) stamping by adopting a convex die a to form soft and hard phases which are regularly and alternately distributed in a sample II, and stamping by adopting a concave die b to form soft and hard phases which are regularly and alternately distributed in a sample III.

3. The method of claim 2, wherein the material that can deformably induce a martensitic transformation is medium manganese steel, high manganese steel, IF steel.

4. The method as claimed in claim 3, wherein the deformation amount of the stamping deformation in the samples II and III obtained by stamping the pretreated odd number of raw material plates I by using a pair of conjugated dies is 50-70%;

the deformation amount of the soft phase is controlled to be 20-40% and the deformation amount of the hard phase is controlled to be 5-20% in the flat stamping process.

5. The method of claim 4, wherein the pre-processing is: selecting a material capable of inducing martensite phase transformation in a deformable mode, tempering the material at a high temperature, cooling the material in air, cutting the material into an inscribed square of a pressure head disc on stamping equipment, and mechanically grinding the surface of an odd number of square plates with equal thickness between 3 and 11 to obtain a raw material plate I; preferably, the temperature of the high-temperature tempering is more than 1000 ℃.

6. The method as claimed in claim 5, wherein the step of stamping the pretreated odd number of raw material plates I by using a pair of conjugated dies to obtain samples II and III comprises the following steps:

assembling detachable dies a on upper and lower pressure heads of a stamping device, coating lubricating oil on the dies, feeding the plates I with the number of (the total number is 1)/2 between the upper and lower dies a, vacuumizing, filling inert gas Ar to atmospheric pressure, stamping and deforming to the expected thickness after heating, taking out a sample, and cooling the sample to room temperature in the air to obtain a sample II;

and assembling detachable dies b conjugated with the dies a on upper and lower pressure heads of the stamping equipment, coating lubricating oil on the dies, feeding the rest plate I between the upper and lower dies b, vacuumizing, filling inert gas Ar to atmospheric pressure, stamping and deforming to the expected thickness after heating, taking out the sample, and cooling the sample to room temperature in the air to obtain a sample III.

7. The method as claimed in claim 6, wherein the process parameters in the process of respectively punching the pretreated odd number of raw material plates I by using a pair of conjugated dies to obtain the samples II and III are as follows: the feeding speed is 100-250 mm/s, the vacuum pumping is carried out until the pressure is 30-100 Pa, the heating speed is 10-30 ℃/min, the heat preservation temperature is 300-600 ℃, the stamping speed is 100-150 mm/s, and the loading load is 100-150 t.

8. The method according to claim 7, characterized in that said flat-stamping is in particular: mechanically polishing and polishing the surfaces of the sample II and the sample III, and stacking the sample II and the sample III according to surface indentation to form a sample IV with a III-II … III laminated structure; assembling detachable plane dies on an upper pressure head and a lower pressure head of the stamping device, sending a sample IV between the plane dies, vacuumizing, filling inert gas Ar to atmospheric pressure, stamping and deforming to the expected thickness after heating to ensure that the sample has good metallurgical bonding, and taking out the sample to cool the sample to room temperature in the air to obtain a heterostructure sample V.

9. The method according to claim 8, wherein the process parameters in the flat-press deformation are: the feeding speed is 100-250 mm/s, the vacuum pumping is carried out until the pressure is 30-100 Pa, the heating speed is 10-30 ℃/min, the heat preservation temperature is 300-600 ℃, the stamping speed is 100-150 mm/s, and the loading load is 100-150 t.

10. The method of claim 1, wherein the heat treatment process comprises: carrying out vacuum annealing treatment on the heterostructure material prepared by flat stamping to eliminate defects and residual stress in the stamping process; the annealing temperature is 300-450 ℃, and the annealing time is 20-30 min.

Technical Field

The invention belongs to the field of preparation of heterogeneous materials, and particularly relates to a method for obtaining a heterogeneous metal sheet by composite stamping.

Background

The metal structure material is widely applied to the fields of military, industry, aviation and the like. High strength and high toughness are performance targets continuously pursued in the field of research of metal structural materials, and people improve the mechanical properties of the materials through various strengthening and toughening mechanisms, so that the materials have better service performance and safety. However, for homogeneous materials, the strength improvement tends to be at the expense of plasticity, severely limiting the application and development of metallic structural materials. Therefore, how to combine strength and plasticity is a hot spot and a focus of research on metallic structural materials.

The heterogeneous material is a novel high-strength high-toughness material which is proposed in recent years. Different from the traditional homogeneous material, the material has the advantages that soft and hard phases with different mechanical properties are constructed on the microscopic scale of the material, and the back stress strengthening effect between the soft and hard phases is utilized to realize the strengthening and toughening of the material at the same time. A search of the literature revealed that "Mechanical properties of coppers/bronzelatinates" published by Ma et al in Acta Materialia (materials journal, 2016, 116: 43-52): role of interface material in the paper, a method for obtaining coarse-grain pure copper/nanocrystalline bronze alternately-distributed isomeric copper alloy structural material by utilizing cumulative rolling and heat treatment is described, wherein the grain size of a nanocrystalline layer is about 100nm, and the grain size of a coarse-grain layer is about 5 μm. The technology has the following characteristics: (1) the equipment is simple, the sample size is large, and the industrial production is easy to realize; (2) the prepared heterogeneous copper alloy plate has excellent mechanical property, and maintains excellent uniform elongation of coarse-grain pure copper to a certain extent while having the high strength of nanocrystalline bronze. However, this technique has the following problems: (1) the requirement on the processing precision of the material surface is high, and the oxidation of an interface is difficult to control; (2) after the multi-pass process, the work hardening capacity of the material is difficult to guarantee.

Further search shows that the Chinese invention patent CN110129700A introduces' Ti-TiAl₃The principle of the preparation method of the metal/intermetallic compound layered composite material is that Ti foil and Al foil are alternately stacked after surface treatment, and high-strength and high-toughness Ti-TiAl is obtained by hot rolling after a pure Ti sheath is sealed and welded at the periphery of a sample₃A metal/intermetallic compound laminate composite. The method is characterized in that: (1) obtaining Ti-TiAl₃The metal/intermetallic compound layered alternate composite material can give consideration to both high strength and high toughness; (2) by adjusting the thickness and the number of the Ti foil and the Al foil laminated layers, the layered composite materials with different thicknesses can be obtained. The limitations are as follows: (1) the processing work before rolling comprises the procedures of surface cleaning, cutting, argon arc welding sealing, heating and the like in multiple times and operationsThe requirement is high, and the production efficiency is low; (2) the bonding strength of the composite interface is difficult to ensure.

Disclosure of Invention

The invention aims to provide a method for obtaining a heterogeneous metal sheet by using composite stamping.

The technical solution for realizing the purpose of the invention is as follows: a method for obtaining heterogeneous metal sheets by using composite stamping adopts a material capable of inducing martensite phase transformation through deformation as an original material, adopts a pair of conjugated dies to respectively heat and stamp an odd number of pretreated raw material plates I to obtain a sample II and a sample III, conjugates a plurality of samples II and samples III according to the surface concave-convex shape to form a gapless III-II … III laminated structure, heats and horizontally stamps, and then carries out heat treatment to form the heterogeneous metal sheets.

Further, the concave-convex degree is adjusted according to different mechanical states; the hardness of the die material is positively correlated with that of the material to be punched, and the die hardness is 75-150 HV higher;

one of the conjugated molds is a convex mold a, and the other conjugated mold is a concave mold b; and a convex die a is adopted to punch to form soft and hard phases which are regularly and alternately distributed in a sample II, and a concave die b is adopted to punch to form soft and hard phases which are regularly and alternately distributed in a sample III.

Furthermore, the material capable of inducing the martensite transformation through deformation is medium manganese steel, high manganese steel and IF steel.

Furthermore, a pair of conjugated dies is adopted to respectively stamp the pretreated odd number of raw material plates I to obtain 50-70% of deformation amount of stamping deformation in the sample II and the sample III;

in the flat stamping process, the deformation amount of the soft phase is controlled to be 20-40%, and the deformation amount of the hard phase is controlled to be 5-20% (the deformation amount of the soft phase and the deformation amount of the hard phase are calculated and considered for shape factors).

Further, the pretreatment comprises the following steps: selecting a material capable of inducing martensite phase transformation in a deformable mode, tempering the material at a high temperature, cooling the material in air, cutting the material into an inscribed square of a pressure head disc on stamping equipment, and mechanically grinding the surface of an odd number of square plates with equal thickness between 3 and 11 to obtain a raw material plate I; preferably, the temperature of the high-temperature tempering is more than 1000 ℃.

Further, the step of respectively stamping the pretreated odd number of raw material plates I by using a pair of conjugated dies to obtain a sample II and a sample III specifically comprises the following steps:

assembling detachable dies a on upper and lower pressure heads of a stamping device, coating lubricating oil on the dies, feeding the plates I with the number of (the total number is 1)/2 between the upper and lower dies a, vacuumizing, filling inert gas Ar to atmospheric pressure, stamping and deforming to the expected thickness after heating, taking out a sample, and cooling the sample to room temperature in the air to obtain a sample II;

and assembling detachable dies b conjugated with the dies a on upper and lower pressure heads of the stamping equipment, coating lubricating oil on the dies, feeding the rest plate I between the upper and lower dies b, vacuumizing, filling inert gas Ar to atmospheric pressure, stamping and deforming to the expected thickness after heating, taking out the sample, and cooling the sample to room temperature in the air to obtain a sample III.

Further, the process parameters in the process of respectively stamping the pretreated odd number of raw material plates I by adopting a pair of conjugated dies to obtain a sample II and a sample III are as follows: the feeding speed is 100-250 mm/s, the vacuum pumping is carried out until the pressure is 30-100 Pa, the heating speed is 10-30 ℃/min, the heat preservation temperature is 300-600 ℃, the stamping speed is 100-150 mm/s, and the loading load is 100-150 t.

Further, the flat stamping specifically comprises: mechanically polishing and polishing the surfaces of the sample II and the sample III, and stacking the sample II and the sample III according to surface indentation to form a sample IV with a III-II … III laminated structure; assembling detachable plane dies on an upper pressure head and a lower pressure head of the stamping device, sending a sample IV between the plane dies, vacuumizing, filling inert gas Ar to atmospheric pressure, stamping and deforming to the expected thickness after heating to ensure that the sample has good metallurgical bonding, and taking out the sample to cool the sample to room temperature in the air to obtain a heterostructure sample V.

Further, the process parameters in the flat stamping deformation are as follows: the feeding speed is 100-250 mm/s, the vacuum pumping is carried out until the pressure is 30-100 Pa, the heating speed is 10-30 ℃/min, the heat preservation temperature is 300-600 ℃, the stamping speed is 100-150 mm/s, and the loading load is 100-150 t.

Further, the heat treatment process comprises the following steps: carrying out vacuum annealing treatment on the heterostructure material prepared by flat stamping to eliminate defects and residual stress in the stamping process; the annealing temperature is 300-450 ℃, and the annealing time is 20-30 min.

Compared with the prior art, the invention has the following remarkable advantages:

(1) the stamping equipment and the working procedure disclosed by the invention are simple and have low operation requirements, and industrial automatic production can be realized.

(2) The whole composite stamping process belongs to a thermal deformation process and is in an Ar atmosphere protection state, so that impurity doping and interface oxidation are effectively avoided, and the prepared sample has good metallurgical bonding.

(3) The heterostructure material prepared by the invention and composed of the soft material deformation induced martensite hard phase can give consideration to both strength and toughness, and can meet the requirements of some special industrial applications to a certain extent.

(4) According to the invention, a two-phase heterostructure with regularly distributed soft and hard phases is formed by locally different deformation amounts, a stamping die can be designed according to actual requirements, the number of laminated layers and the stacking mode are adjusted, the structural design is flexible, and different strengthening and toughening requirements in production and application are met.

(5) The raw materials (such as austenitic steel and ferritic steel) capable of inducing the martensitic transformation by deformation are applied to multiple fields, so that the technology is widely applied.

Drawings

FIG. 1 is a schematic diagram of a stamping process of a conjugate mold according to the present invention; wherein, the drawing a) is the stamping of a die a, and the drawing b) is the stamping of a die b.

Fig. 2 is a schematic drawing of a flat stamping process.

FIG. 3 is a schematic view of a heat treatment process and a heterogeneous metal sheet product, wherein a) is the heat treatment process and b) is the heterogeneous metal sheet product.

Description of reference numerals:

1-stamping device, 2-stamping die a, 3-stamping die b, 4-flat stamping die, and 5-vacuum annealing furnace.

Detailed Description

The present invention is described in further detail below with reference to the attached drawing figures.

In the figure, I is a raw material, II is a sample formed by stamping a die a, III is a sample formed by stamping a die B, IV is a sample with a III-II-III laminated structure, V is a sample formed by laminating and flat stamping, A is an original microstructure of the material, and B is a martensite structure. (in the drawing, the minimum 3-layer structure of the III-II … III stack structure is shown as a representative).

A preparation method of a novel isomeric material. By utilizing a composite stamping process, a structure with both hardness and softness is formed in the material through deformation induction martensite phase transformation, and a three-dimensional controllable and designable heterogeneous structure is prepared.

The composite stamping process specifically comprises the steps of assembling a detachable die a on a pressure head of stamping equipment, stamping a sample I to obtain a sample II, assembling a die B conjugated with the die a to stamp the sample I to obtain a sample III, stacking a plurality of samples II and III according to the concave-convex shape of the surface to form a gapless III-II … III laminated structure, stamping by using the pressure head of an assembling and balancing die, eliminating residual stress through heat treatment to finally form an A/B heterogeneous structure, and strengthening and hardening back stress between a high-toughness phase and a high-strength phase to achieve excellent mechanical properties of high strength and high toughness.

The technical scheme for realizing the aim of the invention comprises three procedures of pretreatment, complex die stamping, flat stamping and heat treatment, and specifically comprises the following steps:

the first step is as follows: pretreatment: selecting materials (such as austenitic steel, ferritic steel, titanium alloy and the like) capable of inducing martensite phase transformation by deformation, tempering the materials at high temperature (above 1000 ℃) and cooling the materials in the air so as to reduce the yield strength and meet the requirements of the subsequent deformation process. Then cutting into an inscribed square of a pressing head disc of the punching equipment, and mechanically grinding the surface of a plurality of square plates (taking odd numbers between 3 and 11) with equal thickness to be used as a raw material sample I.

Step two, complex die stamping: assembling detachable dies a on upper and lower pressure heads of a stamping device, coating lubricating oil on the dies, sending a sample I with the quantity of (the total number is 1)/2 between the upper and lower dies a, vacuumizing, filling inert gas Ar to atmospheric pressure, taking out the sample after stamping deformation (50-70% of deformation) reaches the expected thickness, and cooling the sample to room temperature in the air to obtain a sample II; and assembling detachable dies b conjugated with the dies a on upper and lower pressing heads of the stamping equipment, coating lubricating oil on the dies, sending the rest of the sample I between the upper and lower dies b, vacuumizing, filling inert gas Ar to atmospheric pressure, taking out the sample after stamping deformation (deformation amount of 50-70%) reaches the expected thickness, and cooling the sample to room temperature in the air to obtain a sample III.

Thirdly, flat stamping: the surfaces of samples II and III were mechanically ground and polished, and the samples II and III were stacked in accordance with the surface roughness to form a sample IV having a gapless III-II … III laminated structure. And (3) assembling detachable plane dies on an upper pressure head and a lower pressure head of the stamping equipment, sending the sample IV between the plane dies, vacuumizing, filling inert gas Ar to the atmospheric pressure, controlling the stamping deformation to the expected thickness (1.8-2.2 mm), taking out the sample after the sample has good metallurgical bonding, and cooling the sample to the room temperature in the air to obtain the heterostructure sample V. Wherein the deformation amount of the soft phase A is controlled to be 5-20%, and the deformation amount of the hard phase B is controlled to be 20-40%.

Step four, heat treatment: and (3) carrying out vacuum annealing treatment on the composite stamping formed sample V, eliminating defects and residual stress in the stamping process, and finally obtaining a tough three-dimensional heterogeneous complex structure.

Further, the mechanism of the deformation-induced martensite transformation of the selected material in the pretreatment of the first step is as follows: generally, at M_s～M_dNo martensitic transformation occurs between temperatures, but if an external force is applied thereto, a certain amount of martensitic transformation occurs simultaneously with plastic deformation, the amount of transformation being dependent on the deformation temperature and the amount of deformation. Wherein, the martensite content and the deformation quantity are not in a linear relation, but have a certain incubation period. When the amount of deformation is not equalWhen the mechanical driving force is increased to a value sufficient to compensate for the nucleation driving force (20% of the amount of deformation) required for transformation of austenite to martensite, martensite starts to nucleate in large amounts within austenite, resulting in deformation-induced martensite phase structure.

Furthermore, odd number of square plates with equal thickness between 3 and 11 are selected in the pretreatment in the first step because the laminated structure of III-II-III-II … III is satisfied. And selecting a sample III as an outermost layer, wherein the deformation amount of the A/B phase in the laminated structure can be controlled to meet the requirement (the deformation amount of A is less than 20%, and the deformation amount of B is 20-80%) during the three-step flat stamping.

Further, the process parameters in the stamping deformation of the complex die in the second step are as follows: the feeding speed is 100-250 mm/s, the vacuum pumping is carried out until the pressure is 30-100 Pa, the heating speed is 10-30 ℃/min, the heat preservation temperature is 300-600 ℃, the stamping speed is 100-150 mm/s, and the loading load is 100-150 t.

The technological parameters in the three-step stamping deformation are as follows: the feeding speed is 100-250 mm/s, the vacuum pumping is carried out until the pressure is 30-100 Pa, the heating speed is 10-30 ℃/min, the heat preservation temperature is 300-600 ℃, the stamping speed is 100-150 mm/s, and the loading load is 100-150 t.

Further, the process parameters of the heat treatment in the fourth step are as follows: and (4) protecting in Ar atmosphere, wherein the annealing temperature is 300-450 ℃, and the annealing time is 20-30 min.