Method for enabling galvanized hot-formed steel tailor-welded structure to be uniform in state after being heated

Abstract

The invention relates to the technical field of galvanized hot-formed steel and hot stamping forming, and particularly discloses a method for enabling a galvanized hot-formed steel tailor-welded structure to be uniform in state after being heated, in the tailor-welded structure, the weights of zinc layers on the surfaces of constituent parts with different thicknesses of steel are designed in different weights, and the thinner the zinc layer is, the thicker the zinc layer is; the heating temperature and the heating time are controlled, and the weight of a standard single-face zinc layer of the steel is based on the 1.8 mm thickness part; calculating the weight of a standard single-sided zinc layer of each thickness part of the steel; according to the method, the zinc layer on the surface of the galvanized hot-formed steel is controlled in advance, so that it is guaranteed that the surface states of all parts are more uniform after the tailor-welded structure is heated, the state of the galvanized hot-formed steel tailor-welded structure is uniform after heating, and the welding and coating quality of formed parts is guaranteed.

Description

Technical Field

[0001] This invention relates to the fields of galvanized hot-formed steel and hot stamping forming technology, and specifically to a method for making the welded structure of galvanized hot-formed steel uniform in state after heating. Background Technology

[0002] During the heating process of galvanized hot-formed steel, elements such as Mn, Al, and Fe diffuse into the galvanized surface, forming an oxide layer containing zinc oxide, aluminum oxide, zinc-manganese oxides, and iron oxides. This oxide layer thickens with increasing heating, causing the surface color to change from light gray to light yellow, yellow, brownish-yellow, and finally dark brown. The degree of heating of the sheet metal is related to the weight of the zinc layer, the heating temperature, the heating time, and the sheet thickness. The thicker the sheet metal and the thicker the zinc layer, the slower the heating rate and the lower the degree of surface oxidation. Higher heating temperatures and longer heating times result in a deeper degree of surface oxidation. An excessively thick oxide layer can lead to excessively high surface contact resistance, easily causing spatter during spot welding. Oxide residue in the weld nugget can degrade weld quality. Furthermore, the surface condition significantly affects subsequent electrophoresis, impacting coating quality.

[0003] Under normal circumstances, the thicker the steel plate, the slower the heating rate. Different heating times are used for galvanized hot-formed steel of varying thicknesses to control the surface condition. However, welded structures such as door rings are composed of steel plates of different thicknesses, resulting in varying surface conditions in different areas after heating, leading to poor surface conditions in some locations. Therefore, this study explores a method to ensure uniform heating of galvanized hot-formed steel welded structures, aiming to address the problems of poor coating quality and surface condition in existing galvanized hot-formed steel systems. Summary of the Invention

[0004] In view of the problems existing in the prior art, the purpose of this invention is to provide a method for making the state of galvanized hot-formed steel welded structures uniform after heating.

[0005] The technical solution adopted by this invention to solve its technical problem is: a method for making the state of a galvanized hot-formed steel welded structure uniform after heating, comprising the following steps:

[0006] S1. In the welded structure, the zinc layer weight on the surface of the steel components with different thicknesses is designed to be different, so that the zinc layer thickness is thicker in the thinner parts.

[0007] S2. Control the heating temperature and heating time. The standard single-sided zinc coating weight of steel is based on the 1.8mm thickness portion.

[0008] S3. Calculate the standard single-sided zinc coating weight for each thickness of the steel.

[0009] Specifically, in step S2, the heating temperature range is 770-900℃, and the heating time range is 180-480s.

[0010] Specifically, the preferred heating temperature is 790°C, and the preferred heating time is 300 seconds.

[0011] Specifically, the formula for calculating the weight of the zinc layer in step S3 is as follows:

[0012] ;

[0013] Where: h - material thickness, in mm;

[0014] T - Heating temperature, in °C;

[0015] t - heating time, in seconds;

[0016] G - Zinc coating weight, in g / m 2 .

[0017] Specifically, the actual single-sided zinc coating weight of each thickness portion of the steel is the standard single-sided zinc coating weight G ± 5 g / m. 2 scope.

[0018] Specifically, the steel, after being heated, is light gray, light yellow, or yellow in color at various thicknesses.

[0019] Specifically, after the steel is heated and formed, two welded parts are stacked one on top of the other, and the contact resistance between different thicknesses of the steel is ≤1.5mΩ.

[0020] The present invention has the following beneficial effects:

[0021] The present invention provides a method for ensuring uniformity in the state of galvanized hot-formed steel welded structures after heating. By pre-controlling the zinc layer on the surface of the galvanized hot-formed steel, the surface state of each part of the welded structure is made more uniform and consistent after heating. This uniformity in the state of the galvanized hot-formed steel welded structure after heating is beneficial to ensuring the welding and coating quality of the formed parts. Detailed Implementation

[0022] The technical solutions in the embodiments of the present invention will be described clearly, completely, and in further detail below. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0023] A method for achieving uniformity in the state of galvanized hot-formed steel welded structures after heating involves designing different zinc layer weights for components of varying thicknesses, such as door rings, to make the zinc layer thicker in thinner sections. This ensures complete austenitization on the thicker side during heating, guaranteeing the required strength and microstructure after hot stamping. Simultaneously, it prolongs the diffusion time of elements like Mn, Al, and Fe from the thinner side to the galvanized surface, slowing the oxidation rate and resulting in a thinner oxide layer. This leads to a more uniform state of the galvanized hot-formed steel welded structure after heating. Deeper surface oxidation results in greater surface inhomogeneity and contact resistance differences, which in turn have a greater impact on welding and painting.

[0024] In the welded structure, the zinc layer weight on the surface of the steel components with different thicknesses is designed to be different, so that the zinc layer is thicker in the thinner parts.

[0025] Controlling the heating temperature and time, under suitable heating temperature and time conditions, the heating temperature range is 770-900℃, and the heating time range is 180-480s. The preferred heating temperature is 790℃, and the preferred heating time is 300s. The standard single-sided zinc coating weight of the steel is based on the 1.8mm thickness portion.

[0026] Calculate the standard single-sided zinc coating weight for each thickness of the steel.

[0027] The formula for calculating the weight of the zinc layer is:

[0028] .

[0029] Where: h - material thickness, in mm;

[0030] T - Heating temperature, in °C;

[0031] t - heating time, in seconds;

[0032] G - Zinc coating weight, in g / m 2 .

[0033] The actual single-sided zinc coating weight of each thickness section of the steel is the standard single-sided zinc coating weight G ± 5g / m. 2 scope.

[0034] The color of steel at different thicknesses after heating is light gray, light yellow, or yellow.

[0035] After the steel is heated and formed, two welded parts are stacked one on top of the other, and the contact resistance between the different thicknesses of the steel is ≤1.5mΩ.

[0036] Example 1: Steel is used as the central passageway in the front floor.

[0037] The heating time was 280 seconds and the temperature was 890°C. The parameter comparison before and after the application of the technical solution of this invention is shown in Table 1.

[0038] Table 1. Parameter Comparison Before and After Application

[0039]

[0040] Example 2: Steel is used as the left-side door ring.

[0041] The heating time was 320 seconds and the temperature was 880℃. The parameter comparison before and after the application of the technical solution of this invention is shown in Table 2.

[0042] Table 2. Parameter Comparison Before and After Application

[0043]

[0044] This invention pre-controls the zinc layer on the surface of galvanized hot-formed steel, thereby ensuring a more uniform and consistent surface condition of each part of the welded structure after heating, which is beneficial for subsequent welding and painting.

[0045] This invention is not limited to the above-described embodiments. Anyone should know that any structural changes made under the guidance of this invention, and any technical solutions that are the same as or similar to this invention, fall within the protection scope of this invention.

[0046] The technologies, shapes, and structures not described in detail in this invention are all known technologies.

Claims

1. A method for ensuring uniformity in the state of a galvanized hot-formed steel welded structure after heating, characterized in that, Includes the following steps: S1. In the welded structure, the zinc layer weight on the surface of the steel components with different thicknesses is designed to be different, so that the zinc layer thickness is thicker in the thinner parts. S2. Control the heating temperature and heating time. The standard single-sided zinc coating weight of steel is based on the 1.8mm thickness portion. S3. Calculate the standard single-sided zinc coating weight for each thickness of the steel.

2. The method for achieving uniformity in the state of a galvanized hot-formed steel welded structure after heating, as described in claim 1, is characterized in that... In step S2, the heating temperature range is 770-900℃, and the heating time range is 180-480s.

3. The method for achieving uniformity in the state of a galvanized hot-formed steel welded structure after heating, as described in claim 2, is characterized in that... The preferred heating temperature is 790℃, and the preferred heating time is 300s.

4. The method for achieving uniformity in the state of a galvanized hot-formed steel welded structure after heating, as described in claim 1, is characterized in that... The formula for calculating the weight of the zinc layer in step S3 is as follows: ； Where: h - material thickness, in mm; T - Heating temperature, in °C; t - heating time, in seconds; G - Zinc coating weight, in g / m 2 .

5. The method for achieving uniformity in the state of a galvanized hot-formed steel welded structure after heating, as described in claim 4, is characterized in that... The actual single-sided zinc layer weight of each thickness portion of the steel is the standard single-sided zinc layer weight G ± 5g / m. 2 scope.

6. The method for achieving uniformity in the state of a galvanized hot-formed steel welded structure after heating, as described in claim 1, is characterized in that... The steel, after being heated, is light gray, light yellow, or yellow in color at various thicknesses.

7. The method for achieving uniformity in the state of a galvanized hot-formed steel welded structure after heating, as described in claim 1, is characterized in that... After the steel is heated and formed, two welded parts are stacked on top of each other, and the contact resistance between different thicknesses of the steel is ≤1.5mΩ.

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