TW201809294A - Method of treating surface of austenitic alloy steel - Google Patents

Abstract

The present invention relates to a method of treating a surface of an austenitic alloy steel. The austenitic alloy steel is firstly provided, and subsequently is subjected to a surface treating process. A surface of the austenitic alloy steel includes at least one surface defect. In the aforementioned surface treating process, a cold working step is firstly peformed to the austenitic alloy steel to form a treated steel. And then, a grinding step is performed to the surface of the treated steel, thereby removing the at least one surface defect and enhancing a yield of the steel, futher substantially decreasing a lost of the grinding step.

Description

Surface treatment method for Worthite iron alloy steel

The present invention relates to a surface treatment method for a Worthfield iron-based alloy steel, and more particularly to a surface treatment method for a Worthfield iron-based alloy steel which can remove surface defects and suppress edge crack defects.

Since the Worthfield iron-based alloy steel has more nickel elements and has a face-centered cubic Vostian iron phase structure, it has better high-temperature mechanical properties. Therefore, Worthite iron alloy steel is often used in high temperature environments, such as engine components, engine fasteners, high temperature bearings, furnace enclosures or petrochemical plant pipelines.

In general, the production of Worthite iron-based alloy steel is produced by a hot rolling process by means of continuous casting or die casting of steel. However, due to the original defects in the billet, the surface of the steel after the rolling is easy to have a sheet-like surface defect, which cannot meet the application requirements.

In order to meet the application requirements of the obtained steel, the above surface defects are generally removed by an annealing process and a grinding process. However, such surface defects are generally distributed at a depth of about 0.24 mm (mm), so that the single-sided abrasive loss in the grinding step is generally 4.2%. Therefore, the conventional Worth Iron Foundation Although the surface treatment method of gold steel can remove surface defects, the abrasive material is excessively damaged, and the steel yield is lowered, and the production efficiency of the steel is lowered.

In addition, if the shape of the Worthite iron-based alloy steel is not good or the surface has a side-wave shape defect, the steel obtained after grinding is prone to uneven grinding (such as partial grinding too deep) and causing edge cracking defects. And so on.

In view of this, it is not necessary to provide a surface treatment method for a Worthfield iron-based alloy steel to improve the defects of the conventional surface treatment method.

Therefore, an aspect of the present invention provides a surface treatment method for a Worthfield iron-based alloy steel which can remove surface defects and suppress edge cracking by subjecting a Worthfield iron-based alloy steel to a surface treatment process. Defects, increase the yield, and significantly reduce the material loss of the grinding step.

According to one aspect of the present invention, a surface treatment method for a Worthfield iron-based alloy steel is proposed. This method first provides a Worthfield iron-based alloy steel, and the surface of the Worthfield iron-based alloy steel contains at least one surface defect. Then, the Worthfield iron-based alloy steel is subjected to a surface treatment process. Among them, the surface treatment process first performs a cold working step on the Worthfield iron-based alloy steel to form the Worstian iron-based alloy steel into a processed steel. Next, a surface of the processed steel material is subjected to a grinding step to remove the at least one surface defect.

According to an embodiment of the present invention, the aforementioned Wostian iron-based alloy steel material comprises a hot rolled steel coil or a hot rolled steel sheet.

According to another embodiment of the present invention, the Vostian iron-based alloy is based on 100% by weight of the total weight of the aforementioned Worthfield iron-based alloy steel. The steel material comprises from 7 weight percent to 75 weight percent nickel and from 15 weight percent to 35 weight percent chromium, with the balance being iron.

According to still another embodiment of the present invention, the Vostian iron-based alloy steel further comprises 0% by weight to 0.2% by weight of carbon and 0% by weight based on 100% by weight of the total weight of the aforementioned Worth Iron-based alloy steel. 6.0 weight percent titanium, 0 weight percent to 16.0 weight percent aluminum, 0 weight percent to 12.0 weight percent molybdenum, 0 weight percent to 12.0 weight percent tungsten, 0 weight percent to 20.0 weight percent cobalt, 0 weight percent to 5.0% by weight and 0% by weight to 12.0% by weight of 钽.

According to still another embodiment of the present invention, the aforementioned cold working step may include a rolling step, a forging step, an extrusion step, or a stamping step.

According to still another embodiment of the present invention, the reduction rate of the aforementioned cold working step is greater than 0% and less than or equal to 15.0%.

According to still another embodiment of the present invention, the reduction rate of the aforementioned cold working step is 2.5% to 15.0%.

According to still another embodiment of the present invention, the abrasive loss of the grinding step is less than 4.2%.

According to still another embodiment of the present invention, after performing the foregoing surface treatment process, the method further comprises the steps of performing a solution heat treatment process, performing a sand blasting process, and performing a pickling process.

According to the surface treatment method of the Worthite iron-based alloy steel of the present invention, the Worthfield iron-based alloy steel obtained has substantially no surface defects, and the surface treatment method has a high finished product rate and greatly reduces the grinding step. Material loss. Secondly, this method can also suppress edge cracking of steel and has better surface quality.

100‧‧‧ method

110‧‧‧Provide the steps of the Worthite iron alloy steel

120‧‧‧Surface treatment process

121‧‧‧Steps of cold working to form a step of processing steel

123‧‧‧Steps for the grinding step

For a more complete understanding of the embodiments of the invention and the advantages thereof, reference should be made to the description below and the accompanying drawings. It must be emphasized that the various features are not drawn to scale and are for illustrative purposes only. The relevant schema description is as follows:

Fig. 1A is an optical micrograph showing a side crack defect of a Worthfield iron-based alloy steel according to an embodiment of the present invention.

Fig. 1B is a partially enlarged optical micrograph showing a side crack defect of a Worthfield iron-based alloy steel according to an embodiment of the present invention.

FIG. 2 is a flow chart showing a surface treatment method of a Worthfield iron-based alloy steel according to an embodiment of the present invention.

The making and using of the embodiments of the invention are discussed in detail below. However, it will be appreciated that the embodiments provide many applicable inventive concepts that can be implemented in a wide variety of specific content. The specific embodiments discussed are illustrative only and are not intended to limit the scope of the invention.

The term "edge crack defect" as used in the present invention means that the deformation of the steel material is too large (for example, the amount of cut is too large), and cracks occur at the edge of the steel material, and further cutting is required, thereby reducing the quality of the steel and its application value. Please refer to FIG. 1A and FIG. 1B, which respectively show Vostian according to an embodiment of the present invention. An optical micrograph of the edge cracking defect of an iron-based alloy steel, and an optical microscope image of a partial enlargement of the edge cracking defect. According to FIG. 1A and FIG. 1B, when the steel material has edge crack defects, the steel material needs to be further cut to meet the application requirements, but the material loss thereof will be greatly increased.

Next, the term "range of surface defects" as used in the present invention refers to the distribution area of surface defects on the surface of the steel material, and "the depth of distribution of surface defects" refers to the depth of surface defects from the surface of the steel material.

Referring to FIG. 2, a flow chart of a surface treatment method for a Worthfield iron-based alloy steel according to an embodiment of the present invention is shown. The method 100 is to first provide a Worthfield iron-based alloy steel as shown in step 110. Wherein, the surface of the Vostian iron-based alloy steel material comprises at least one surface defect. In one embodiment, the Worthfield iron-based alloy steel does not contain edge cracking defects.

In a specific example, the Vostian iron-based alloy steel of the present invention may include, but is not limited to, a hot-rolled steel coil, a hot-rolled steel sheet, other suitable Wostian iron-based alloy steel, or any combination of the above steel materials.

This Vostian iron-based alloy steel mainly contains the Worthfield iron phase structure of Face Center Cubic (FCC). The material of the Worthfield iron-based alloy steel may include, but is not limited to, nickel-based alloys such as Alloy 800H, Alloy A-286, Alloy 625 or Alloy 718, and Wostian iron-based stainless steels such as 309 stainless steel or 310 stainless steel, Alloy 400 or Alloy 500K nickel-copper alloy, other suitable materials or any combination of the above materials.

The Vostian iron-based alloy steel contains 7 wt% to 75 based on 100 wt% of the total weight of the aforementioned Worthite iron-based alloy steel. Weight percent nickel and 15 weight percent to 35 weight percent chromium, with the balance being iron.

In one embodiment, the Vostian iron-based alloy steel further comprises 0% by weight to 0.2% by weight of carbon, and 0% by weight to 6.0% by weight based on 100% by weight of the total weight of the Vostian iron-based alloy steel. Titanium, 0 weight percent to 16.0 weight percent aluminum, 0 weight percent to 12.0 weight percent molybdenum, 0 weight percent to 12.0 weight percent tungsten, 0 weight percent to 20.0 weight percent cobalt, 0 weight percent to 5.0 weight percent铌 and 0% by weight to 12.0% by weight of 钽.

After step 110, the surface treatment process 120 of the aforementioned Vostian iron-based alloy steel material is performed. Wherein, the surface treatment process 120 includes a cold working step and a grinding step.

First, the aforementioned Worstian iron-based alloy steel material is subjected to a cold working step to form a processed steel material as shown in step 121. The cold working step may include, but is not limited to, a rolling step, a forging step, an extrusion step, a stamping step, other suitable processing steps, or any combination of the above.

When the cold working step is performed, the applied stress can force the steel to deform, and the surface defects on the surface of the steel will be subjected to work hardening, and the mechanical properties of the surface defects (such as hardness decrease and brittle fracture) ), which in turn makes the surface defects more loose. Among them, due to the looseness of the surface defects, the steel is affected by the deformation of the steel. When the steel is deformed, the structure of the surface defects will also "move". For example, when the cold working step is a rolling step, it is affected by the rolling stress, and the steel is The surface portion is elongated and deformed in the rolling direction, and the thickness of the steel is thinned. Secondly, the applied rolling force can break and lengthen the surface defect structure, thereby driving the surface portion of the surface defect tissue to "move", thereby increasing the distribution range of the surface defects and reducing the distribution depth of the surface defects. In other words, when the Worthfield iron-based alloy steel is subjected to a cold working step, the distribution of surface defects can be varied, but the distribution depth becomes shallow.

In one embodiment, the reduction rate of the cold working step is greater than 0% and less than or equal to 15.0%, and preferably from 2.5% to 15.0%. The aforementioned reduction rate (Δh/h ₀ ) refers to the percentage of the cut thickness (Δh) and the thickness of the incoming steel (h ₀ ), wherein the cut thickness (Δh) is the thickness of the incoming steel (h ₀ ) and the discharge The difference in steel thickness (h ₁ ). Accordingly, the reduction rate referred to in the present invention can be expressed by the following formula (I):

If the reduction rate of the cold working step is greater than 15.0%, the excessive reduction rate will cause the steel to be excessively deformed, and the edge of the steel is prone to cracks, thereby generating edge crack defects.

In addition, the Worstian iron-based alloy steel having a poor initial shape or a surface defect such as a side wave can be eliminated by the processing stress applied by the cold working step described above, and the subsequent Worstian iron can be improved. The quality of alloy steel.

After performing the aforementioned cold working step, the surface of the processed steel material obtained in step 121 is subjected to a grinding step, as shown in step 123, to completely remove at least one of the surface defects described above. Wherein, by the aforementioned cold working step, the structure of the surface defect becomes more brittle, so the grinding step can easily remove the table. Face defects. Secondly, the aforementioned cold working step can also reduce the distribution depth of the surface defects (that is, the distribution of the surface defects is closer to the steel surface), so the grinding step of the present invention can completely remove the surface defects only by removing less steel. Accordingly, the material loss of the grinding step can be greatly reduced. In one embodiment, the abrasive loss of the grinding step is less than 4.2%.

In an embodiment, after performing the foregoing grinding step, the method of the present invention may further comprise a solution heat treatment process, a sand blasting process, a pickling process, and the like for the obtained Worth Iron-based alloy steel, and It can further enhance the surface quality of Worthfield iron-based alloy steel to meet various application needs.

In an application example, the Vostian iron-based alloy steel treated by the method of the present invention does not have surface defects and edge crack defects. Secondly, according to the method of the present invention, the distribution depth of the surface defects in the Worthite iron-based alloy steel becomes shallower, and the surface defect structure is loose and brittle, so the Worthfield iron-based alloy steel is obtained. Can have a higher yield.

In another application example, the surface treatment method of the present invention can also be applied to a steel material having less oxidation degree, good ductility, and less brittleness during cold working, and can remove surface defects while suppressing occurrence of edge crack defects.

The following examples are used to illustrate the application of the present invention, and are not intended to limit the present invention, and various modifications and refinements can be made without departing from the spirit and scope of the invention.

Example 1

First, a Wostian iron-based alloy steel sheet is provided and has a thickness of 6.15 mm. Then, the steel sheet was subjected to a rolling step to form a processed steel sheet having a thickness of 6 mm (that is, a reduction ratio of 2.5%). Next, the grinding step was carried out under the conditions of grinding 0.05 mm per pass. After 4 passes, the surface defects of the steel sheet can be completely removed. Observed visually, the edges of the obtained steel sheets did not have edge crack defects.

Thereafter, the obtained steel plate is sequentially subjected to a solution heat treatment process, a sand blasting process, and a pickling process. The temperature of the solution heat process is 1125 ° C, and the time is 5 minutes to 10 minutes. The blasting process is carried out using steel balls numbered SAE-110 and has a particle size of from 0.3 mm to 0.6 mm. The pickling process is carried out using an acid pickling solution of nitric acid and hydrofluoric acid, and the pickling liquid contains nitric acid having a concentration of 120 g/L and hydrofluoric acid of 25 g/L.

Example 2 to Example 6 and Comparative Example 1 and Comparative Example 2

The second to sixth embodiments, the comparative example 1 and the comparative example 2 were substantially the same as the surface treatment method of the first embodiment, except that the examples 2 to 6 and the comparative example 1 and the comparative example were used. 2 The surface treatment process was performed using steel plates having different thicknesses, respectively, and the cold working steps of Examples 2 to 6 and Comparative Example 1 and Comparative Example 2 had different reduction rates. Next, the grinding step is performed in accordance with the distribution depth of the surface defects to completely remove the surface defects. Similarly, after the surface treatment process was carried out, it was visually observed whether or not the edge of the obtained steel sheet had edge crack defects, and the obtained results and the above-described process conditions are as shown in Table 1. Among them, "○" means that the edge of the steel sheet does not have edge crack defects, and "X" represents that the edge of the steel sheet has edge crack defects.

Comparative example 3

The Worth Iron-based alloy steel sheet of Comparative Example 3 was treated by a conventional method. First, a Worth Iron-based alloy steel plate having a thickness of 6 mm is provided. Then, the steel sheet is annealed, wherein the annealing process is maintained at 1050 ° C for 3 minutes. Next, the annealed steel sheet was subjected to a grinding process under conditions of 0.05 mm per pass. After 5 passes, the surface defects of the steel sheet can be completely removed. Next, it was visually observed whether the edge of the obtained steel sheet had edge crack defects. The results obtained are shown in Table 1.

According to the contents of the first table and the evaluation results, the cold working step of the surface treatment process of the present invention can make the surface defect tissue looser and reduce the distribution depth of the surface defects, and can be easily performed by the subsequent grinding step. And completely remove surface defects. Among them, the depth of the surface defects is reduced, the grinding depth of the subsequent grinding step can be greatly reduced, and the grinding loss of the grinding step is reduced, thereby increasing the yield of the steel and shortening the time cost of the steel, thereby improving the Voss The production efficiency of Tiantie alloy steel.

Secondly, when the reduction rate of the cold working step is in the above range, the Worthfield iron-based alloy steel after the surface treatment process does not have edge crack defects and has better surface quality.

Accordingly, the surface treatment method of the present invention can completely remove the surface defects of the steel and improve the finished product rate of the steel. Second, when the cold processing step When the reduction ratio is in the range described above, the surface treatment method of the present invention can further suppress edge cracking of the steel material.

The present invention has been disclosed in the above embodiments, and is not intended to limit the present invention. Any one of ordinary skill in the art to which the present invention pertains can make various changes without departing from the spirit and scope of the invention. The scope of protection of the present invention is therefore defined by the scope of the appended claims.

Claims (9)

A surface treatment method for a Worthite iron-based alloy steel, comprising: providing a Worthfield iron-based alloy steel, wherein one surface of the Worthfield iron-based alloy steel includes at least one surface defect; and the Worthite iron The alloy steel is subjected to a surface treatment process, wherein the surface treatment process comprises: performing a cold working step on the Vostian iron-based alloy steel to form a processed steel; and performing a grinding step on the surface of the processed steel to The at least one surface defect is removed. The surface treatment method of the Vostian iron-based alloy steel according to the first aspect of the invention, wherein the Vostian iron-based alloy steel material comprises a hot-rolled steel coil or a hot-rolled steel sheet. The surface treatment method of the Vostian iron-based alloy steel according to the first aspect of the invention, wherein the Vostian iron-based alloy steel material comprises 7 based on the total weight of the Vostian iron-based alloy steel. The weight percentage is up to 75 weight percent nickel and 15 weight percent to 35 weight percent chromium, with the balance being iron. The surface treatment method of the Worthite iron-based alloy steel as described in claim 3, wherein the Worthfield iron-based alloy steel is used. The total weight of the material is 100% by weight, and the Vostian iron-based alloy steel further comprises 0% by weight to 0.2% by weight of carbon, 0% by weight to 6.0% by weight of titanium, 0% by weight to 16.0% by weight of aluminum, and 0% by weight. Weight percent to 12.0 weight percent molybdenum, 0 weight percent to 12.0 weight percent tungsten, 0 weight percent to 20.0 weight percent cobalt, 0 weight percent to 5.0 weight percent bismuth, and 0 weight percent to 12.0 weight percent bismuth. The surface treatment method of the Worthite iron-based alloy steel according to the first aspect of the invention, wherein the cold working step comprises a rolling step, a forging step, an extruding step or a pressing step. The surface treatment method of the Vostian iron-based alloy steel according to the first aspect of the invention, wherein the reduction ratio of the cold working step is greater than 0% and less than or equal to 15.0%. The surface treatment method of the Worthfield iron-based alloy steel according to claim 6, wherein one of the cold working steps is 2.5% to 15.0%. The surface treatment method of the Wostian iron-based alloy steel according to the first aspect of the invention, wherein the grinding loss of one of the grinding steps is less than 4.2%. The surface treatment method of the Vostian iron-based alloy steel according to the first aspect of the patent application, after performing the surface treatment process, further comprises: performing a solution heat treatment process; performing a sandblasting process; and performing a pickling process Process.