(19)
(11)EP 3 502 304 A1

(12)EUROPEAN PATENT APPLICATION
published in accordance with Art. 153(4) EPC

(43)Date of publication:
26.06.2019 Bulletin 2019/26

(21)Application number: 17840864.7

(22)Date of filing:  30.06.2017
(51)International Patent Classification (IPC): 
C23C 10/52(2006.01)
(86)International application number:
PCT/CN2017/091034
(87)International publication number:
WO 2018/032888 (22.02.2018 Gazette  2018/08)
(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR
Designated Extension States:
BA ME
Designated Validation States:
MA MD

(30)Priority: 19.08.2016 CN 201610690168

(71)Applicant: Chongqing Dayou Surface Technology Co., Ltd
Chongqing 400020 (CN)

(72)Inventor:
  • REN, Yuzhong
    Chongqing City 400020 (CN)

(74)Representative: Zaboliene, Reda 
METIDA Law Firm Zaboliene and Partners Business center VERTAS Gyneju 16
01109 Vilnius
01109 Vilnius (LT)

  


(54)STEEL SURFACE-MODIFIED STRUCTURE FORMED USING ZINC-NICKEL INFILTRATION LAYER, AND METHOD FOR PREPARATION THEREOF


(57) The present disclosure provides a surface modified steel member with anti-corrosion properties formed by nickel and zinc penetration. The surface modified steel member includes alloy structures with anti-corrosion properties formed on a steel substrate. The surface modified steel member, from outside to inside, includes an alloy deposition layer and a metallic diffusion layer. The steel substrate is made of medium-carbon steel or medium-carbon alloy steel. The alloy deposition layer includes zinc ferrum alloys. The metallic diffusion layer includes pearlite crystals, ferrite crystals, and quenching and tempering structures. The steel substrate comprising carbon element which has a content in a range from 0.3% to 0.65% in the steel substrate by weight. The surface modified steel member with anti-corrosion properties has a Micro Vickers Hardness in a range from 240 to 500. The surface modified steel member has a good corrosion resistance, which can reduce the losses caused by steel corrosion. The present disclosure further provides a method for making the surface modified steel member formed by nickel and zinc penetration.




Description

FIELD



[0001] The present disclosure relates to surface modified steel members, and more particularly, to a surface modified steel member with anti-corrosion property and a method for making the same.

BACKGROUND



[0002] Corrosion of steel causes huge losses to the world. According to researches, steel which is scrapped because of corrosion every year accounts for more than 20% of annual steel production, causing a value of loss about 7000 hundred million dollars . The loss value is far more than the total loss value caused by natural calamities such as earthquake, flood, and typhoon. Nowadays, some anti-corrosion technologies are developed to ease the steel corrosion. However, the protective coatings made by the anti-corrosion technologies are not a complete answer to corrosion, and the hardness thereof is low. Nickel and zinc penetration can allow the workpiece to have higher corrosion resistance, higher wear resistance, and high vibration resistance. Thus, it is needed to manufacture a surface modified steel structure with anti-corrosion formed by nickel and zinc penetration.

SUMMARY



[0003] What is needed, is a surface modified steel structure with anti-corrosion formed by nickel and zinc penetration.

[0004] The present disclosure provides a surface modified steel member formed by nickel and zinc penetration. The surface modified steel member comprises alloy structures with anti-corrosion properties formed on a steel substrate. The surface modified steel member with anti-corrosion properties, from outside to inside, comprises an alloy deposition layer and a metallic diffusion layer. Wherein the steel substrate is made of medium-carbon steel or medium-carbon alloy steel. The alloy deposition layer comprises zinc ferrum alloys, the metallic diffusion layer comprises pearlite crystals, ferrite crystals, and quenching and tempering structures. The steel substrate comprises carbon element which has a content in a range from 0.3% to 0.65% in the steel substrate by weight. The surface modified steel member with anti-corrosion properties has a Micro Vickers Hardness in a range from 240 to 500.

[0005] Furthermore, the surface modified steel member with anti-corrosion properties is not quenched and tempered, the metallic diffusion layer has a Micro Vickers Hardness greater than a Micro Vickers Hardness of the steel substrate.

[0006] Furthermore, the surface modified steel member with anti-corrosion properties is subjected to a quenching and tempering process and comprises quenching and tempering structures after the quenching and tempering process, the metallic diffusion layer has a Micro Vickers Hardness not greater than a Micro Vickers Hardness of the steel substrate.

[0007] Furthermore, when the surface modified steel member is not quenched and tempered, a color of the pearlite crystals in the metallic diffusion layer is lighter than a color of the pearlite crystals in the steel substrate after 10 seconds to 50 seconds by immersing the surface modified steel member in an etchant including nitric acid and alcohol, with a concentration from 1% to 5%.

[0008] Furthermore, when the surface modified steel member is quenched and tempered, the metallic diffusion layer on the medium-carbon steel or the medium-carbon alloy steel comprises the quenching and tempering structures, a bright white color remains on the metallic diffusion layer after 10 seconds to 50 seconds by immersing the surface modified steel member in an etchant including nitric acid and alcohol, with a concentration from 1% to 5%.

[0009] Furthermore, a thickness of the alloy deposition layer is in a range from 60 microns to 110 microns, and a thickness of the metallic diffusion layer is in a range from 30 microns to 120 microns.

[0010] Furthermore, the steel substrate of the surface modified steel member with anti-corrosion properties is made of medium-carbon steel or medium-carbon alloy steel.

[0011] The present disclosure further provides a method for modifying surface of steel material, comprising:

S1, providing a steel substrate which is made of medium-carbon steel or medium-carbon alloy steel;

S2, cleaning oil and grease adhering to surface of the steel substrate by alkaline solution;

S3, cleaning rust on the surface of the steel substrate obtained by S1 by grit blasting;

S4, loading the steel substrate and a penetrating agent into an enclosed steel container, heating the steel container to a temperature in a range from 370 degrees Celsius to 430 degrees Celsius, and rotating the steel container at a speed in a range from 5 RPM to 10 RPM during the heating, the penetrating agent comprising Zn powder in a range from 25% to 30% by weight, Ni powder in a range from 2% to 2.5% by weight, Al powder in a range from 1% to 2.5% by weight, rare earth metallic powder in a range from 0.5% to 1.5% by weight, ammonia chloride in a range from 1% to 4% by weight, and Al2O3 powder in a remaining range by weight;

S5, washing.


BRIEF DESCRIPTION OF THE DRAWINGS



[0012] 

FIG. 1 is a metallographic view of an embodiment of a steel material with anti-corrosion.

FIG. 2 is a metallographic view of a cross-section of a steel substrate of steel No. 45 after surface modification, which is not quenched and tempered.

FIG. 3 is a metallographic view of a cross-section of a steel substrate of steel No. 45 after surface modification, which is subjected to a quenching and tempering process.

FIG. 4 is a metallographic view of a cross-section of a steel substrate of 42CrMoA after surface modification, which is subjected to a quenching and tempering process.

FIG. 5 is metallographic view of a cross-section of a steel substrate of 35CrMo after surface modification, which is subjected to a quenching and tempering process.

FIG. 6 is a metallographic view of a cross-section of a steel substrate of 35VB after surface modification, which is subjected to a quenching and tempering process.

FIG. 7 is metallographic view of a cross-section of a steel substrate of 40Cr after surface modification, which is subjected to a quenching and tempering process.


DETAILED DESCRIPTION



[0013] Implementations of the disclosure will now be described, by way of embodiments only, with reference to the attached figures. The embodiments shown and described above are only examples. Changes may be made in the detail within the principles of the present disclosure, up to and including the full extent established by the broad general meaning of the terms used in the claims. It will, therefore, be appreciated that the embodiments described above may be modified within the scope of the claims.

[0014] The present disclosure provides a surface modified method for making steel material with anti-corrosion by nickel and zinc penetration. The method includes following steps.

[0015] S1, a steel substrate is provided, which is made of medium-carbon steel or medium-carbon alloy steel.

[0016] One or more steel substrates are provided, which are made of medium-carbon steel or medium-carbon alloy steel.

[0017] S2, the steel substrate is subjected to pretreatment.

[0018] In an embodiment, the pretreatment includes cleaning of oil and grease adhering to the surface by alkaline solution (or by ultrasonic waves and heating) and cleaning of rust on the surface by grit blasting.

[0019] Cleaning of oil and grease by alkaline solution: the alkaline solution can include a basic salt, and the basic salt includes caustic soda, sodium carbonate, sodium phosphate tribasic, sodium silicate, or sodium borate. The basic salt can include at least two of the above components. Furthermore, the alkaline solution can further include a steel chelating agent and an organic additive agent to improve the surface cleaning. The steel chelating agent includes at least one of elhylene diamine tetraacetic acid (EDTA), sodium citrate, and triethanolamine. The organic additive agent includes at least one of ethylene glycol and ethylene glycol monoethyl ether.

[0020] Cleaning of oil and grease by ultrasonic waves (ultrasonic cleaning) is using ultrasound waves to agitate washing fluid, thereby producing high forces directly or indirectly on the contaminants to disperse, emulsify, or separate the contaminants, thereby achieving cleaning. The ultrasonic cleaning needs a proper washing fluid.

[0021] Cleaning of oil and grease by heating is heating the steel substrate to a temperature equal to or higher than the ignition point of the oil and the grease, thereby causing the oil and the grease to be burned and volatilized.

[0022] The steel substrate before cleaning may have contaminants adhering to the surface, including the oil and the grease, and dust. If the contaminants are not cleaned, the contaminants will be carbonized to form carbonization during heating, and the carbonization affects the appearance and the surface modification effect. Cleaning of the oil and grease can clean the contaminants adhering to the surface, thereby laying a foundation for the following surface modification.

[0023] Grit blasting can further clean the surface of the steel substrate. The grit blasting forcibly propels a stream of small hard balls under high pressure to remove rust and oxide skin, thereby allowing the surface to obtain desired roughness and brightness and laying the foundation for the following surface modification.

[0024] S3, a penetrating agent is provided.

[0025] The penetrating agent is prepared according to the type and the desired anti-corrosion properties of the alloy. The penetrating agent is in a form of powders, which includes Zn powder in a range from 25% to 30% by weight, Ni powder in a range from 2% to 2.5% by weight, Al powder in a range from 1% to 2.5% by weight, rare earth metallic powder in a range from 0.5% to 1.5% by weight, ammonia chloride in a range from 1% to 4% by weight, and Al2O3 powder in a remaining range by weight. Specific concentration of each type of powder in the penetrating agent can be varied according to the material of the steel substrate or its intended application.

[0026] S4, the surface of the steel substrate is modified.

[0027] The steel substrate obtained by step S1 and the penetrating agent obtained by step S2 are loaded into an enclosed steel container. The steel container is heated, and is rotated during the heating. By conduction heating by the penetrating agent, the steel substrate and the penetrating agent can be at same temperature, and the penetrating agent can penetrate into the steel substrate to modify the surface of the steel substrate. In the present disclosure, the steel container and is rotated at a speed in a range from 5 Revolutions Per minute (RPM) to 10 RPM during the heating. The speed for rotating the steel container ensures even heating of the penetrating agent and the steel substrate. Thus, the penetrating agent evenly penetrates into the steel substrate, thereby obtaining the steel material with anti-corrosion.

[0028] The steel substrate is made of medium-carbon steel or medium-carbon alloy steel.

[0029] In an embodiment, the steel container is heated at a temperature in a range from 370 degrees Celsius to 430 degrees Celsius. The temperature for heating the steel container is also important, a higher temperature provides a significantly larger penetrating rate by the atoms in the penetrating agent. The specific temperature for heating and the specific time period for heating the steel container can be varied according to the material of the steel substrate or its intended application. A time period for the surface modification is in a range from 1 hour to 10 hours.

[0030] The steel substrate can be preheated and the preheated steel substrate and the penetrating agent are mixed and loaded into the steel container. The steel substrate can also be not preheated, and the steel substrate and the penetrating agent are mixed at room temperature. The steel substrate and the penetrating agent during heating the steel container.

[0031] Before step S4, the steel substrate can be preheated as needed. The steel substrate can be preheated to a temperature from 400 degrees Celsius to 420 degrees Celsius.

[0032] S5, washing.

[0033] The steel substrate after step S3 is naturally cooled. After removing dust on the surface, the steel substrate is then washed by water to remove remaining powders and other impurities.

[0034] The steel substrate can be subjected to a quenching and tempering process before the pretreatment. The steel substrate can form quenched and tempered structures on the surface after the quenching and tempering process.

[0035] A surface modified steel member with anti-corrosion properties can be formed on the steel substrate after the above steps. FIG. 1 illustrates a metallographic view of the steel material after surface modification. The steel material, from outside to inside, includes an alloy deposition layer, a metallic diffusion layer, and a steel substrate. The metallic diffusion layer defines a transition region between the steel substrate and the alloy deposition layer.

Embodiment 1



[0036] FIG. 2 is a metallographic view of a cross-section of a steel substrate of steel No. 45 after surface modification, which is not quenched and tempered. In this embodiment, the steel substrate is made of medium-carbon steel, specifically, steel No. 45. The surface of the steel substrate of steel No. 45 is modified as follows.

[0037] In this embodiment, the steel substrate is made of medium-carbon steel, specifically, steel No. 45. The surface of the steel substrate of steel No. 45 is modified as follows.

[0038] The steel substrate was subjected to a pretreatment, including cleaning of oil and grease by alkaline solution and removal of rust by grit blasting. The processes for cleaning of oil and grease by alkaline solution and removal of rust by grit blasting are described above and no more details here.

[0039] A penetrating agent was provided, which was in a form of powders and included Zn powder of 30% by weight, Ni powder of 2% by weight, Al powder of 2.5% by weight, rare earth metallic powder of 0.5% by weight, ammonia chloride of 4% by weight, and Al2O3 powder in a remaining range by weight.

[0040] Furthermore, the surface of the steel substrate was modified. The steel substrate after the pretreatment and the penetrating agent were both at room temperature when loaded to an enclosed steel container. The steel container was heated, and was rotated during the heating. By conduction heating by the penetrating agent, the steel substrate and the penetrating agent could be at same temperature, and the penetrating agent could penetrate into the steel substrate to modify the surface of the steel substrate. In the present disclosure, the steel container was rotated at a speed of 5 RPM during the heating. The speed for rotating the steel container could ensure even heating of the penetrating agent and the steel substrate, thereby modifying the surface of the steel substrate. A time period for the surface modification was 1 hours, the heating temperature was at 400 degrees Celsius, to obtain the surface modified steel member with anti-corrosion.

[0041] In this embodiment, the steel No. 45 and the penetrating agent were not preheated during mixing. That is, the steel No. 45 and the penetrating agent were mixed at ambient temperature and then loaded into the steel container to perform surface modification in the steel container. In detail, the steel substrate and the penetrating agent were mixed at room temperature.

[0042] In this embodiment, the steel substrate was steel No. 45 on which a surface modified steel member was formed. The surface modified steel member on the steel No. 45, from outside to inside, included an alloy deposition layer and a metallic diffusion layer. The innermost layer was the steel substrate.

[0043] Referring to FIG. 2, the color of the pearlite crystals in the metallic diffusion layer was lighter than the color of the pearlite crystals in the steel substrate. The metallic diffusion layer had a Micro Vickers Hardness greater than a Micro Vickers Hardness of the steel substrate. The thickness of the metallic diffusion layer was 100 microns. The metallic diffusion layer included pearlite crystals and ferrite crystals.

Embodiment 2



[0044] Referring to FIGS. 3-7, FIG. 3 is a metallographic view of a steel substrate of steel No. 45 after surface modification, which is subjected to a quenching and tempering process. FIG. 4 is a metallographic view of a cross-section of a steel substrate of 42CrMoA after surface modification, which is subjected to a quenching and tempering process. FIG. 5 is metallographic view of a cross-section of a steel substrate of 35CrMo after surface modification, which is subjected to a quenching and tempering process. FIG. 6 is a metallographic view of a cross-section of a steel substrate of 35VB after surface modification, which is subjected to a quenching and tempering process. FIG. 7 is metallographic view of a steel substrate of 40Cr after surface modification, which is subjected to a quenching and tempering process.

[0045] In this embodiment, the steel substrates were made of medium-carbon steel or medium-carbon alloy steel, specifically including steel No. 45, 42CrMoA, steel 35CrMo, steel 35VB, and steel 40Cr. Different surface modified structures were finally obtained.

[0046] Differences from the Embodiment 1 were those:
  1. (1) In this embodiment, the penetrating agent was in a form of powders and included Zn powder of 25% by weight, Ni powder of 2.5% by weight, Al powder of 1% by weight, rare earth metallic powder of 1.5% by weight, ammonia chloride of 1% by weight, and Al2O3 powder in a remaining range by weight.
  2. (2) In this embodiment, each of the steel substrates in this embodiment was subjected to a quenching and tempering process before the pretreatment. Each of the surface modified steel members with anti-corrosion had a total Micro Vickers Hardness in a range from 240 to 400.


[0047] Then, surface modified steel members were formed after surface modification of the steel substrates. The surface modified steel member, from outside to inside, included an alloy deposition layer and a metallic diffusion layer. The innermost layer was the steel substrate.

[0048] The quenching and tempering structures were formed on the steel substrate after the quenching and tempering process. Specifically, the quenching and tempering structures were included in the metallic diffusion layer. Furthermore, the quenching and tempering structures were at least one of tempered sorbate and tempered troostite.

[0049] Each of the surface modified steel members was subjected to an etching process by immersing the surface modified steel member in an etchant including nitric acid and alcohol, with a concentration from 1% to 5%. Results show that a bright white color remained on the metallic diffusion layer after several seconds (usually 10 seconds to 50 seconds), indicating that each surface modified steel member had a good corrosion resistance. The thickness of each metallic diffusion layer was in a range from 30 microns to 100 microns. The Micro Vickers Hardness of each metallic diffusion layer, formed by surface modification of a specific steel substrate, was slightly less than the Micro Vickers Hardness of the steel substrate. The metallic diffusion layer, formed by surface modification of the steel substrate, included metallographic structures which were at least one of tempered sorbate and tempered troostite.

[0050] Compared to prior art, the surface modified steel structure according to the present disclosure has a good corrosion resistance, which can reduce the losses caused by steel corrosion. Furthermore, the basic mechanical properties of the steel substrate are not changed, but the abrasion resistance of the steel substrate is improved because of the high hardness imparted by these processes.

[0051] The embodiments shown and described above are only examples. The disclosure is illustrative only, and changes may be made in the detail within the principles of the present disclosure, up to and including the full extent established by the broad general meaning of the terms used in the claims. It will, therefore, be appreciated that the embodiments described above may be modified within the scope of the claims.


Claims

1. A surface modified steel member formed by nickel and zinc penetration, the surface modified steel member comprising alloy structures with anti-corrosion properties formed on a steel substrate, characterized in that:

the surface modified steel member with anti-corrosion properties, from outside to inside, comprising an alloy deposition layer and a metallic diffusion layer;

wherein the steel substrate is made of medium-carbon steel or medium-carbon alloy steel, the alloy deposition layer comprises zinc ferrum alloys, the metallic diffusion layer comprises pearlite crystals, ferrite crystals, and quenching and tempering structures, the steel substrate comprises carbon element which has a content in a range from 0.3% to 0.65% in the steel substrate by weight, the surface modified steel member with anti-corrosion properties has a Micro Vickers Hardness in a range from 240 to 500.


 
2. The surface modified steel member formed by nickel and zinc penetration of claim 1, wherein the surface modified steel member with anti-corrosion properties is not quenched and tempered, the metallic diffusion layer has a Micro Vickers Hardness greater than a Micro Vickers Hardness of the steel substrate.
 
3. The surface modified steel member formed by nickel and zinc penetration of claim 1, wherein the surface modified steel member with anti-corrosion properties is subjected to a quenching and tempering process and comprises quenching and tempering structures after the quenching and tempering process, the metallic diffusion layer has a Micro Vickers Hardness not greater than a Micro Vickers Hardness of the steel substrate.
 
4. The surface modified steel member formed by nickel and zinc penetration of claim 2, wherein when the surface modified steel member is not quenched and tempered, a color of the pearlite crystals in the metallic diffusion layer is lighter than a color of the pearlite crystals in the steel substrate after 10 seconds to 50 seconds by immersing the surface modified steel member in an etchant including nitric acid and alcohol, with a concentration from 1% to 5%.
 
5. The surface modified steel member formed by nickel and zinc penetration of claim 3, wherein when the surface modified steel member is quenched and tempered, the metallic diffusion layer on the medium-carbon steel or the medium-carbon alloy steel comprises the quenching and tempering structures, a bright white color remains on the metallic diffusion layer after 10 seconds to 50 seconds by immersing the surface modified steel member in an etchant including nitric acid and alcohol, with a concentration from 1% to 5%.
 
6. The surface modified steel member formed by nickel and zinc penetration of claims 1-5, wherein a thickness of the alloy deposition layer is in a range from 60 microns to 110 microns, and a thickness of the metallic diffusion layer is in a range from 30 microns to 120 microns.
 
7. The surface modified steel member formed by nickel and zinc penetration of claim 6, wherein the steel substrate of the surface modified steel member with anti-corrosion properties is made of medium-carbon steel or medium-carbon alloy steel.
 
8. A method for modifying surface of steel material, comprising:

S1, providing a steel substrate which is made of medium-carbon steel or medium-carbon alloy steel;

S2, cleaning oil and grease adhering to surface of the steel substrate by alkaline solution;

S3, cleaning rust on the surface of the steel substrate obtained by S1 by grit blasting;

S4, loading the steel substrate and a penetrating agent into an enclosed steel container, heating the steel container to a temperature in a range from 370 degrees Celsius to 430 degrees Celsius, and rotating the steel container at a speed in a range from 5 RPM to 10 RPM during the heating, the penetrating agent comprising Zn powder in a range from 25% to 30% by weight, Ni powder in a range from 2% to 2.5% by weight, Al powder in a range from 1% to 2.5% by weight, rare earth metallic powder in a range from 0.5% to 1.5% by weight, ammonia chloride in a range from 1% to 4% by weight, and Al2O3 powder in a remaining range by weight;

S5, washing.


 




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