CN109252018B

CN109252018B - Surface-strengthened metal matrix and surface treatment method

Info

Publication number: CN109252018B
Application number: CN201811379537.8A
Authority: CN
Inventors: 陈志凯; 何冰; 朱青海
Original assignee: Jiangsu Xugong Construction Machinery Research Institute Co ltd
Current assignee: Jiangsu Xugong Construction Machinery Research Institute Co ltd
Priority date: 2018-11-20
Filing date: 2018-11-20
Publication date: 2020-08-07
Anticipated expiration: 2038-11-20
Also published as: CN109252018A

Abstract

The invention relates to a metal matrix, wherein at least one surface of the metal matrix is provided with a laser strengthening area, the laser strengthening area comprises a plurality of linear strengthening grains, and the strengthening grains are distributed on the surface in a grid shape. The metal matrix has a hardened surface and a low deformation rate.

Description

Surface-strengthened metal matrix and surface treatment method

Technical Field

The invention relates to the field of surface treatment, in particular to a surface-strengthened metal matrix and a surface treatment method.

Background

The paver is a construction equipment mainly used for paving various materials on the upper base surface and the surface layer of the highway, and mainly comprises a broken stone and asphalt concrete paver. The asphalt concrete paver is used for uniformly paving an asphalt mixture on a road base layer and realizing the paving of an asphalt pavement through preliminary compaction and leveling.

Fig. 1 shows a schematic view of a portion of a screed of a paving machine. During construction, the chain wheel 40 drives the material conveying plate to move on the material conveying bottom plate 30. Because the chain wheel 40 has higher hardness and smaller contact area (chain width) with the material conveying bottom plate 30, the material conveying bottom plate 30 is easily seriously abraded, and an abrasion area 41 is formed in the contact area of the chain wheel 40 and the material conveying bottom plate 30. In addition, the asphalt contains a large amount of hard particles such as stones and sand, which accelerates the wear failure of the feeding base plate 30.

The laser melting strengthening is that laser with certain power density interacts with metal to make local area of metal surface be heated to high temperature above melting point instantaneously to melt it, then the melted extremely thin surface layer metal is quickly solidified by means of heat absorption and heat dissipation action of cold metal matrix.

In the process of melting and strengthening, local rapid melting and rapid solidification occur in the laser action area of the metal surface, so that a non-equilibrium cast structure with an extremely fine structure is formed, and the structure has high hardness, good wear resistance and good corrosion resistance.

Disclosure of Invention

The inventors have found that the related art employs a line-by-line scanning of the entire area during surface laser fusion, which causes deformation of the metal substrate, particularly the metal plate. Is not favorable for the subsequent utilization of the metal base material.

In some aspects, a metal substrate is provided, at least one surface of the metal substrate having a laser-enhanced region, the laser-enhanced region including a plurality of linear reinforcing ridges, the plurality of linear reinforcing ridges intersecting to form a grid.

In some embodiments, the mesh is a polygonal mesh. The polygons may be triangles, quadrilaterals, pentagons, etc.

In some embodiments, the grid is a parallelogram grid.

In some embodiments, the plurality of linear reinforcing ridges includes a plurality of first linear reinforcing ridges and a plurality of second linear reinforcing ridges, and the plurality of first linear reinforcing ridges and the plurality of second linear reinforcing ridges intersect to form a grid.

In some embodiments, the plurality of first linear reinforcing ridges are parallel to each other.

In some embodiments, the plurality of second linear reinforcing ridges are parallel to each other.

In some embodiments, the plurality of linear reinforcing ridges comprises a plurality of linear reinforcing ridges.

In some embodiments, the distance between two adjacent reinforcing lines (e.g., reinforcing lines parallel to each other) is 30-50 mm.

In some embodiments, the linear reinforcing texture has a depth (e.g., laser-formed depth of fusion) of d-1 to 3 mm.

In some embodiments, the width w of the linear reinforcing ridges is 3-5 mm.

In some embodiments, at least one surface of the metal substrate is provided with a first laser strengthened region and a second laser strengthened region, wherein the first laser strengthened region and the second laser strengthened region are respectively positioned at two sides of an axis of the surface, and the axis is a straight line which is along the surface and passes through the center of the surface.

In some embodiments, the center of the surface refers to the center of the circle that least circumscribes the outer contour of the surface.

In some embodiments, the surface has a shape that is symmetrical with respect to the axis, which is the axis of symmetry of the surface.

In some embodiments, the surface has an axis of symmetry along the length, the axis being a straight line axis of symmetry of the surface along the length and through the center of the surface.

In some embodiments, the first laser-strengthened region and the second laser-strengthened region are continuously distributed along the length of the surface.

In some embodiments, the first laser-strengthened region and the second laser-strengthened region are located at edges of the surface.

In some embodiments, the first laser-enhanced regions and the second laser-enhanced regions are distributed (e.g., spread out in a grid) in a range from the edge amm to bmm, a is 0 to 20, and b is 40 to 60.

In some embodiments, the first laser-strengthened region and the second laser-strengthened region are distributed (e.g., spread out in a grid) over an interval of 0-50 mm from the edge.

In some embodiments, the linear reinforcing ridges are angled from 30 to 60 ° (e.g., 40 to 50 °) from the axis.

In some embodiments, the first laser-strengthened region and the second laser-strengthened region are symmetric to each other with the axis as an axis of symmetry.

In some embodiments, the first laser-strengthened region has the same shape and/or area as the second laser-strengthened region.

In some embodiments, there is a non-laser-strengthened region between the first and second laser-strengthened regions.

In some embodiments, the material of the metal matrix is steel, such as mild steel.

In some embodiments, the metal substrate is plate-shaped.

In some embodiments, the metal substrate is planar plate-shaped.

In some embodiments, the metal substrate is in the form of a rectangular plate.

In some embodiments, the metal substrate is rectangular with a width of 300 to 600 mm.

In some embodiments, the metal substrate is in the form of a rectangular plate, the surface is an upper or lower surface of the plate-like metal substrate, and the axis is a straight line centered on the rectangle and parallel to the length of the rectangle.

In some embodiments, the contour of the surface is a right-angled quadrilateral, such as a rectangle, e.g., a square. Here, the rectangular quadrangle means a shape substantially having a rectangular quadrangle. The sides of the quadrilateral may not be strictly straight lines.

In some embodiments, the laser-strengthened region is a laser-hardened region.

In some embodiments, the material of the metal substrate is a low carbon steel, such as Hardox 400 low carbon steel.

In some embodiments, the metal substrate is a screed sole plate, such as a screed sole plate of a paving machine, such as a screed sole plate of an asphalt concrete paving machine.

In some aspects, a method for treating a surface of a metal substrate is provided, which includes performing local strengthening treatment on at least one surface of the metal substrate to form a laser strengthened region on the surface, wherein the laser strengthened region includes a plurality of linear strengthening grains, and the strengthening grains intersect to form a grid.

In some embodiments, the first laser strengthened region and the second laser strengthened region are located on either side of an axis of the surface, the axis being a straight line along the surface and passing through a center (e.g., geometric center) of the surface;

the method for implementing local strengthening treatment comprises the following steps:

performing 1A local strengthening treatment on the position, on the surface of the metal matrix, of a first laser strengthening area to be formed, drawing a series of 1A strengthening grains which are parallel to each other along a first direction, wherein the extension line of the first strengthening grains along the first direction is intersected with the axis to form a 1A acute included angle;

performing 2A local strengthening treatment on the position of a second laser strengthening area to be formed on the surface of the metal matrix, and drawing a series of 2A strengthening grains which are parallel to each other along a second direction; the extension line of the second strengthening grain along the second direction is intersected with the axis to form a 2A acute included angle;

performing 1B local strengthening treatment on a position, on the surface of a metal matrix, where a first laser strengthening region is to be formed, drawing a series of 1B strengthening grains which are parallel to each other along a first direction, wherein a 1B acute included angle is formed by intersecting an extension line of the first strengthening grain along the first direction with the axis;

performing 2B local strengthening treatment on the position of a second laser strengthening area to be formed on the surface of the metal matrix, and drawing a series of 2B strengthening grains which are parallel to each other along a second direction; the extension line of the second strengthening grain along the second direction is intersected with the axis to form a 2B acute angle included angle;

the 1A reinforced grains and the 2A reinforced grains are intersected to form a grid;

the 1B reinforced grains and the 2B reinforced grains are intersected to form a grid.

In some embodiments, an extension of the 1A enhanced texture can intersect the 2A enhanced texture along the surface;

in some embodiments, an extension of the 1B reinforcing texture can intersect the 2B reinforcing texture along the surface.

In some embodiments, the 1A acute included angle is α degrees, the 1B acute included angle is γ degrees, the 2A acute included angle is degrees, and the 2B acute included angle is β degrees, characterized by any of:

·α＝；

·γ＝β；

α being 30 to 60 (e.g., 40 to 50);

β being 30 to 60 (e.g., 40 to 50);

γ is 30 to 60 (for example, 40 to 50);

30 to 60 (e.g., 40 to 50).

In some embodiments, α ═ γ ═ β;

in some embodiments, the 1 st acute included angle is different from the 1 st acute included angle in the opening direction;

in some embodiments, the acute 2A angle is different from the acute 2B angle in opening direction.

In some embodiments, the local strengthening treatment is performed in the following order:

performing 1A local strengthening treatment on the surface of the metal substrate at the position where a first laser strengthening region is to be formed;

performing 2A local strengthening treatment on the surface of the metal substrate at the position where a second laser strengthening region is to be formed;

performing 1B local strengthening treatment on the surface of the metal substrate at the position where a first laser strengthening region is to be formed;

and carrying out 2B local strengthening treatment on the surface of the metal substrate at the position where the second laser strengthening region is to be formed.

In some embodiments, the laser strengthened metal matrix of the present disclosure is obtained by the method of the present disclosure.

In some embodiments, the laser-strengthened metal matrix produced by the methods of the present disclosure is a laser-strengthened metal matrix of the present disclosure.

In some embodiments, laser surface strengthening includes laser consolidation, laser amorphization, laser shock peening, and laser infiltration, laser chemical vapor deposition, laser physical vapor deposition, and the like.

In the present invention, unless otherwise specified, scientific and technical terms used herein have the meanings that are commonly understood by those skilled in the art. Also, the laboratory procedures referred to herein are all conventional procedures widely used in the corresponding field. Meanwhile, in order to better understand the present invention, the definitions and explanations of related terms are provided below.

In some embodiments, the operations are performed at ambient temperature and pressure unless otherwise specified.

As used herein, the term "ambient temperature" refers to 25 ± 5 ℃.

As used herein, the term "atmospheric pressure" refers to 1 atmosphere ± 5%.

As used herein, the term "about" should be understood by those skilled in the art and will vary to some extent depending on the context in which it is used. If the use of the term is not clear to one of ordinary skill in the art based on the context in which the term is used, then "about" means no more than plus or minus 10% of the stated particular value or range.

Advantageous effects

(1) Compared with the laser strengthening areas which are continuously and densely distributed, the latticed laser strengthening areas not only reduce the processing cost and improve the processing efficiency, but also have better strengthening effect. For example,

the latticed laser strengthening area plays a role in blocking the abrasion grooves, and a large-size continuous abrasion area is prevented from being formed on the matrix in a certain direction;

if hard particles (such as sand and stone) exist in the friction interface, when the hard particles move to the laser strengthening area, the movement form can be changed from sliding to rolling, so that the friction coefficient of the friction interface can be reduced, and the service life of the wear-resistant part is further prolonged.

(2) By adopting the surface treatment method disclosed by the invention, the treated metal matrix basically does not deform, and particularly, the treated plate-shaped metal matrix basically does not bend and deform, so that the subsequent application of the metal matrix is very facilitated.

Embodiments of the present invention will be described in detail below with reference to the drawings and examples, but those skilled in the art will understand that the following drawings and examples are only for illustrating the present invention and are not to be construed as limiting the scope of the present invention. Various objects and advantageous aspects of the present invention will become apparent to those skilled in the art from the accompanying drawings and the following detailed description of the preferred embodiments.

Drawings

Fig. 1 shows a schematic view of a portion of a screed of a paving machine.

FIG. 2 is a schematic illustration of a substrate provided with laser-enhanced regions;

FIG. 3 is a schematic illustration of yet another substrate having a laser-enhanced region on a surface thereof;

FIG. 4 is a schematic view of the curvature detection of a steel mesh;

FIG. 5 is a photograph of a substrate having laser-enhanced regions;

FIG. 6 is a photograph of a substrate having laser-enhanced regions.

Detailed Description

Embodiments of the present invention will be described in detail below with reference to examples, but those skilled in the art will appreciate that the following examples are only illustrative of the present invention and should not be construed as limiting the scope of the present invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products commercially available.

Example 1

(1) A low-carbon steel sheet was prepared, the steel sheet composition being as follows:

as shown in FIG. 2, the steel plate has a rectangular shape, a length of 1200mm, a width of 450mm and a thickness of 10 mm.

The laser strengthening areas are selected to be close to the edges of two long sides of the rectangle and are respectively a first laser strengthening area 11 and a second area to be strengthened by laser 12. The first region to be laser-strengthened 11 and the second region to be laser-strengthened 12 cover regions having a length of 1200mm and a width of 50 mm. The first laser strengthening area 11 and the second area to be laser strengthened 12 are located on two sides of a central axis 15 of the rectangle along the length direction and are close to the edges of the long sides.

(2) Surface cleaning: and (3) polishing the surface to be strengthened to remove coatings such as paint, oil stain and rust, and then cleaning the surface by using alcohol to remove impurities such as residual metal particles, low-melting-point substances and the like on the surface.

(3) Laser fusing: carrying out laser fusion treatment on a to-be-laser strengthening area on the surface of the material conveying bottom plate by using laser beams, wherein the laser power is 1800W, the scanning speed is 20mm/s, and the defocusing amount (the distance between a laser focus and a target object) is 130mm (positive defocusing);

specifically, as shown in fig. 2, the following operations are performed in order,

① at the location where the first laser strengthened region 11 is to be formed, a 1A local strengthening treatment is performed, a series of 1A strengthened ridges parallel to each other are drawn along the 1A direction, the right side of fig. 2 shows a schematic of one 1A strengthened ridge, as shown in the dashed box in fig. 2, the extension of the 1A strengthened ridge along the 1A direction intersects the axis to form a 1A acute angle, the 1A acute angle α is 45 degrees, and the distance S1A between two adjacent parallel 1A strengthened ridges is 40 mm.

② at the location where the second laser strengthened region 12 is to be formed, a 2A local strengthening treatment is performed, a series of 2A strengthening ridges parallel to each other are drawn along the 2A direction, the right side of fig. 2 shows a schematic of one 2A strengthening ridge, as shown in the dashed box in fig. 2, the extension of the 2A strengthening ridge along the 2A direction intersects the axis to form a 2A acute angle, the 2A acute angle is 45 degrees, and the distance S2A between two adjacent parallel 2A strengthening ridges is 40 mm.

③ at the location where the first laser strengthened region 11 is to be formed, a 1B local strengthening treatment is performed, a series of 1B strengthening ridges parallel to each other are drawn along the 1B direction, the right side of fig. 2 shows a schematic of one 1B strengthening ridge, as shown in the dashed box in fig. 2, the extension of the 1B strengthening ridge along the 1B direction intersects the axis to form a 1B acute angle, the 1B acute angle γ is 45 degrees, and the distance S1B between two adjacent parallel 1B strengthening ridges is 40 mm.

④ at the location where the second laser strengthened region 12 is to be formed, 2B local strengthening treatment is performed, a series of 2B strengthening ridges parallel to each other are drawn along the 2B direction, the right side of fig. 2 shows a schematic of one 2B strengthening ridge, as shown in the dashed box in fig. 2, the extension of the 2B strengthening ridge along the 2B direction intersects the axis to form a 2B acute angle, the 2B acute angle β is 45 degrees, and the distance S2B between two adjacent parallel 2B strengthening ridges is 40 mm.

The sequence of formation of the 1 st enhanced texture, the 2 nd enhanced texture, the 1 st enhanced texture, and the 2 nd enhanced texture is further schematically depicted on the right side of fig. 2 by arrows and step numbers ① - ④.

FIG. 5 is a photograph of a steel sheet after the strengthening treatment of example 1.

Comparative example 1

Comparative example 1 differs from example 1 in that:

laser fusing: the zones to be laser-strengthened on the surface of the delivery substrate were subjected to laser fusing using a laser beam of the same parameters as in example 1, but the fusing path was different.

As shown in fig. 3, the first region to be laser-strengthened 11 and the second region to be laser-strengthened 12 of comparative example 1 cover an area having a length of 1200mm and a width of 50 mm. The first laser strengthening area 11 and the second area to be laser strengthened 12 are located on two sides of a central axis 15 of the rectangle along the length direction and are close to the edges of the long sides. However, in comparative example 1, the laser-strengthened stripes were laser-fused line by line in a straight fusing path parallel to the length direction with little gap between the lines until the fused stripes spread over the first and second laser-strengthened

zones

11 and 12. Fig. 6 is a photograph of the steel sheet after the strengthening treatment of comparative example 1.

Except for this, comparative example 1 was the same as the other steps of example 1.

Example of detecting amount of deformation

The method for detecting the bending degree of the steel plate comprises the following steps:

as shown in FIG. 4, a first straight rule 31 of 1500mm is horizontally abutted against the surface 30 of the steel plate in the longitudinal axis direction, and the center of the first straight rule 31 is located on a vertical line passing through the center of the surface 30 of the steel plate. The maximum distance H from the surface of the steel sheet to the first ruler 31 is then measured with the second ruler 32. The detection results are as follows:

	h-before surface strengthening A	H-after surface strengthening B	Deformation ratio%
				Example 1	0.3mm	2mm	0.11％
Comparative example 1	0.3mm	8mm	0.51％

Deformation rate (B-a)/first linear length × 100%

According to the deformation detection result, the method can effectively strengthen the surface of the metal matrix, can keep the flatness of the metal matrix, and is beneficial to subsequent application of the metal matrix.

In addition, after the laser melting treatment, the special surface texture formed by the combination of the laser melting areas is prepared on the surface of the low-carbon steel conveying base plate, and the surface treatment mode has the following advantages:

(1) after the surface of the low-carbon steel is treated by using a laser melting technology, the metal in a laser irradiation area is rapidly melted and solidified for recrystallization, the grain size is extremely small, the hardness can be obviously improved based on a fine grain strengthening principle, and the problem of poor hardenability of the traditional heat treatment process of the low-carbon steel can be solved;

(2) after the treatment of the laser melting and fusing technology, the metal material is melted and recrystallized, so that the material cannot be added on the surface of the material conveying bottom plate, and the assembly requirements of parts cannot be influenced; the strengthening phase is directly embedded in the matrix and is metallurgically bonded with the matrix;

(3) the method comprises the following steps of locally processing a working surface by using a laser fusing technology, reducing heat input by formulating a special surface texture, and optimizing a scanning path, so that the deformation of a material conveying bottom plate is controlled without influencing the form and position tolerance of parts;

(4) the melting area is used as a main wear-resistant unit because the melting area can effectively support the chain wheel and reduce the damage to the matrix due to a fine-grain strengthening mechanism.

While specific embodiments of the invention have been described in detail, those skilled in the art will understand that: various modifications and changes in detail can be made in light of the overall teachings of the disclosure, and such changes are intended to be within the scope of the present invention. The full scope of the invention is given by the appended claims and any equivalents thereof.

Claims

1. A surface treatment method of a metal substrate, wherein the metal substrate is plate-shaped;

the method comprises the steps of performing local strengthening treatment on at least one surface of a metal matrix to form a laser strengthening area on the surface, wherein the laser strengthening area comprises a plurality of linear strengthening grains, the linear strengthening grains are linear strengthening grains, and the strengthening grains are intersected to form a grid;

a first laser strengthening area and a second laser strengthening area are arranged on at least one surface of the metal matrix, the first laser strengthening area and the second laser strengthening area are respectively positioned on two sides of an axis of the surface, a non-laser strengthening area is arranged between the first laser strengthening area and the second laser strengthening area, and the axis is a straight line which is along the surface and passes through the center of the surface;

the first laser strengthening region and the second laser strengthening region are positioned on two sides of an axis of the surface, wherein the axis is a straight line which is along the surface and passes through the center of the surface;

the first laser strengthening region and the second laser strengthening region are symmetrical to each other by taking the axis as a symmetry axis, and the first laser strengthening region and the second laser strengthening region have the same shape and area;

the 1B reinforced grains and the 2B reinforced grains are intersected to form a grid;

the angle of 1A acute angle contained angle is α degrees, the angle of 1B acute angle contained angle is gamma degree, the angle of 2A acute angle contained angle is the degree, the angle of 2B acute angle contained angle is β degrees, its characterized in that is following any one:

·α＝；

·γ＝β；

·α＝30～60；

·β＝30～60；

·γ＝30～60；

·＝30～60。

2. the method according to claim 1, characterized by any of the following:

-the depth of the linear reinforcing texture is 1-3 mm;

-the width of the linear reinforcing ridges is 3-5 mm.

3. The method according to claim 1, characterized by any of the following:

-the first laser-strengthened region and the second laser-strengthened region are continuously distributed along the length of the surface;

-the first laser-strengthened region and the second laser-strengthened region are located at the edge of the surface.

4. The method according to claim 1, characterized by any of the following:

-the material of the metal matrix is steel;

-said metal matrix is flat;

-the contour of the surface is a right-angled quadrilateral;

-the laser-strengthened region is a laser-hardened region.

5. The method according to claim 1, characterized by any of the following:

-the material of the metal matrix is low carbon steel;

-said metal substrate is a screed feeder floor;

-the laser-strengthened zone is a laser-fused strengthened zone.

6. The method according to claim 1, characterized by any of the following:

·α＝＝γ＝β；

the opening directions of the 1 st acute included angle and the 1 st acute included angle are different;

the opening directions of the 2A acute angle included angle and the 2B acute angle included angle are different;

along the surface, an extension of the 1A enhanced texture may intersect the 2A enhanced texture;

an extension of the 1B strengthening texture can intersect the 2B strengthening texture along the surface.

7. The method of claim 1, wherein the local strengthening treatment is performed in the following order:

8. A surface-strengthened metal matrix, wherein at least one surface of the surface-strengthened metal matrix is provided with a laser strengthening region, the laser strengthening region comprises a plurality of linear strengthening grains, and the plurality of linear strengthening grains are intersected to form a grid;

the surface-strengthened metal matrix is prepared by the method of any one of claims 1 to 7.