JPS596321A - Working method of quasi-austenitic stainless steel sheet - Google Patents

Abstract

PURPOSE:To precisely realize the aimed performance of product and further to always make the standardization of performance possible, by controlling the working induced martensitic amount according to the conditions of chemical composition and working temperature of steel sheet in the press work of the titled steel sheet. CONSTITUTION:The mantensitic amount corresponding to the aimed performance of products, by at first the chemical composition of material, mainly the contents of Ni and C and by correlatively examining the amount of chemical component and the working amount of products to be worked. Then, the working temperature corresponding to this amount is established, the blank and the press mold being regulated to this established temperature by heating before press working, and the press working is carried out. Thus, the martensitic amount delicately affected by the mutual correlation of chemical component amount and working temperature can be regulated to a required value, various kinds of performance corresponding to this amount being able to be obtained and the performance can be always made standardized at the same time, too.

Description

Detailed Description of the Invention This invention relates to a press working method for quasi-austenitic stainless steel sheets in which a martensitic structure is induced by Various metal-based materials are used. Among these materials, materials such as stainless steel and aluminum are often used as materials for press working, as they have excellent appearance and corrosion resistance properties even without surface treatment. . However, aluminum generally has a problem of low strength, so its range of application is limited. In this point,
Stainless steel has high strength and various other excellent properties, so it has a very wide range of applications as a press working material.

Here, the term "quasi-austenitic stainless steel sheet" refers to an austenitic stainless steel sheet among various austenitic stainless steel sheets that has a property of inducing a martensitic structure during press working, for example, drawing work. This type of quasi-austenitic stainless steel corresponds to, for example, ausbunite stainless steels ranging from SUS 301 to Sus 316 L specified in G4303 of the J Engineering S Standard. Note that herein, the amount of martensite induced due to processing as described above will be referred to as the amount of processing-induced martensite.

This quasi-austenitic stainless steel sheet is characterized by its chemical composition (especially Ni and carbon content),
Processed milk (for plastic deformation by pressing), processing temperature (
It has a processing characteristic in which the amount of deformation-induced martensite is subtly influenced by the blank and press die (V) etc. during 7"less processing. Also, the amount of deformation-induced martensite depends on the product after processing. It has a great effect on mechanical properties such as strength (hardness) and elongation (toughness).In addition, the method of confirming the amount of martensite in a product is to check the amount of martensite using a ferrite scope, a non-destructive test. Check the site volume.

FIGS. 1 to 6 are diagrams schematically showing the characteristics in press working of a quasi-austenitic stainless steel plate. In these figures, the amount of deformation-induced martensite is shown in the upper part as a marden-sweet scene. 1st
The figure shows that the amount of martensite increases as the amount of processing increases.

Note that FIGS. 2 to 6 are characteristic diagrams when the amount of processing is constant. Figure 2 shows martensite B.

Indicates that strength (hardness) increases with increase in
FIG. 3 shows that, on the contrary, elongation (toughness) decreases as the amount of martensite increases. FIG. 4 shows that martensite m= decreases as the processing temperature increases. Figure 5 shows that as the N1 content increases, the amount of martensite decreases, and Figure 6 shows that, contrary to the case in Figure 5, as the C content increases, the martensite force increases. . As shown in these figures, quasi-austenitic stainless steel has the characteristic that the amount of deformation-induced martensite varies depending on the type conditions even when the material is the same. For example, JIS
Taking 5TJS 304 specified in G4303 as an example, the C content is 0.08 or less and the N1 content is 8.
It is specified in the range of 00 to 10.50 inches. Therefore,
Even if such JIS standard stainless steel sheets are purchased, the content L1 of C and N1 varies within the specified range, and therefore the rib marten size (M) after press working will take various values. As a result, there will be differences in the performance of the processed product, in other words, the mechanical properties, etc.
Corrosion resistance may also deteriorate. Therefore, quasi-austenitic stainless steel copper plates are cheaper than austenitic ones, but in press working, as mentioned above, the performance of the product, especially the mechanical properties, tends to vary, and the desired performance ( There is a problem in that it is difficult to accurately obtain mechanical properties, corrosion resistance, etc., and the pressing method is a problem.

(3) Prior Art and Problems In the conventional press working method for quasi-austenitic stainless steel sheets, the chemical composition conditions and working temperature conditions of the stainless steel sheets were not taken into account. Unfortunately, as mentioned above, even if JIS Jt7 stainless steel sheets are purchased, there is some variation in the N1 and C content in the purchased lot 4U, and the ambient air temperature varies between summer and winter. There is a problem in that the performance of the product varies depending on the purchase lot (4σ) or depending on the season, due to differences in the temperatures of the blank and the mold.

Furthermore, since press working is usually a processing method for mass-producing the same product, it is surprisingly necessary to process a large number of products in succession. Therefore, as the pressing operation progresses, the temperature of the press die (sword mincer, die, etc.) itself increases due to the frictional heat and pressure of the working surface. The heat of this press mold is transferred to the blank, raising the temperature of the blank itself. As a result, for example, the processing temperature conditions will be different between the first product and the 30th product, and the amount of martensite will be different, as shown in the above-mentioned FIG. 4. Therefore, a difference in the amount of martensite means a difference in product performance, that is, strength (hardness) and elongation (toughness), as shown in FIGS. 2 and 3 above.

Figure 7 is a diagram showing how the amount of martensite changes with respect to the manufacturing order (manufacturing number) of products continuously processed by the conventional press working method, and at the same time shows the change in the amount of martensite caused by the difference in Nt content. It is a figure showing a state.

As is clear from the figure, as the mold temperature increases, the amount of martensite decreases rapidly from the first product to about the 30th product, and then up to about the 60th product. decreases gradually, and then becomes a nearly constant value as the mold temperature stabilizes. Further, in FIG. 7, even in the same BUS 304, when the N1 content is 8.5% and 9.0-, the martensite amount differs by about 5 to 10% as shown in the figure. In this way, in press working of quasi-austenitic stainless steel, the working temperature and the amount of chemical components of the material are related to each other and have a subtle effect on the amount of martensite. As mentioned above, the conventional processing method has the drawback that the product performance varies widely and the target performance cannot always be maintained constant. In view of these shortcomings, by skillfully controlling the amount of deformation-induced martensite, the target performance of the product can be accurately achieved, and this performance can always be maintained in the product by press processing of semi-austenitic stainless steel sheets. The purpose is to provide a method.

(5) Structure of the invention According to the present invention, when press working a quasi-austenitic stainless steel plate, the amount of chemical components of the stainless steel sheet is detected in advance, and the amount of chemical components and the amount of processing to be processed are detected in advance. By setting a processing temperature corresponding to the target performance and processing amount of the product, preheating or cooling the stainless steel plate and press die to the set temperature, and then press-working the stainless steel plate, A press for quasi-austenitic stainless steel sheet, characterized in that the amount of strain-induced martensite induced in the press process is controlled to a desired value, so that the target performance of the processed product can always be consistently obtained. This is achieved by providing a processing method.

(6) Embodiments of the invention Examples of the invention will now be described in detail based on the drawings. 8th
Figures 1 to 10 are diagrams for explaining the present invention in detail.

FIG. 8 is a diagram showing changes in the amount of martensite in products that have been continuously processed based on the processing method of the present invention with respect to the manufacturing order (manufacturing number).
This corresponds to the figure. As is clear from Figure 8,
According to the processing method of the present invention, from the first product to
It is shown that the amount of martensite is maintained at a substantially constant value up to the 50th product. Comparing this Fig. 8 with the above-mentioned Fig. 7 (conventional example), it is found that the product produced by the machined blade method of the present invention has a higher amount of martensite than the product produced by the conventional processing method. It can be seen that it is maintained extremely stably.

Now, the processing method in this case is to first detect the chemical components of the material (mainly Ni and C content 1) from the mill sheet,
The amount of chemical components and the processing amount of the product to be processed are considered in correlation to set the amount of martensite that corresponds to the target performance of the product, then the processing temperature corresponding to this amount of martensite is set, and the press Before processing, the blank and press mold are heated and adjusted to the set processing temperature, and then press processing is performed. Note that each of the above-mentioned setting values is set based on data on processing characteristics of the material as shown in FIGS. 1 to 6 mentioned above obtained in advance. Further, although the manufacturing order is only shown up to the 150th piece in FIG. 8, in reality, the amount of martensite in the product is maintained constant even in subsequent processing. The fact that the amount of martensite is constant in this way means that the product performance (mainly mechanical properties) is constant, as shown in FIGS. 2 and 3 above.

In the above embodiment, the temperature of the press die and the material (blank) is controlled by heating them together, but the temperature may be controlled depending on the needs of product performance.

FIG. 9 shows an example of a p-type diaphragm with a built-in heater. In the same figure, reference numeral 10 indicates a base, and a base 1 with
A punch 11 is fixed on the 0. An upper die 12 that fits into the punch 11 with an appropriate gap and is movable in the vertical direction.
and a lower die 13 are attached to the press stand 14. The material (blank) sandwiched between the upper die 12 and the lower die 13 is placed between the upper and lower dies 12 and 13 downward (arrow A).
) and is fitted with a punch to perform a drawing process and become the product 15. The upper die 12 and the lower die 13 have
Built-in pipe heater 16 with thermostat,
The temperatures of the upper die 12 and the lower die 13 are controlled to desired values by the heaters. In addition, the code|symbol 17 shows a cushion bin. In addition to this, there is also a method of heating the press mold (die) by embedding the arm hole and running hot water through it.

On the other hand, if you want to cool it down, use water during the embedding process.

The temperature of the press mold can be controlled by flowing cooling water, liquid nitrogen, etc., or by using dry ice.

When heating the material (blank), there is a method of heating the material (blank) by stacking a plurality of blanks 21 on the armpit heel 20, as shown in FIG. 10, for example. In addition to this, there is also a method of immersing the blank in hot water, a method of using a hot grate, etc. On the other hand, in the case of cooling, there are methods using P-lye ice, liquid nitrogen, a refrigerator, etc. In addition, the method of checking the amount of martensite in the product is to check the amount of martensite using a ferrite scope, a non-destructive test.

(7) Effects of the Invention As explained in detail above, the method of pressing semi-austenitic stainless steel sheets of the present invention accurately achieves the target performance of the product, and always brings this performance to the product in a constant manner. There are great effects, such as the possibility of compassion.

[Brief explanation of drawings]

Figures 1 to 6 are diagrams showing the processing characteristics of quasi-ausdenitic stainless steel sheets, and Figure 7 is the change in the amount of deformation-induced martensite (Q) with respect to the manufacturing order (manufacturing number) of products using the conventional processing method. Figure 8 shows the process-induced martensite for the manufacturing order (manufacturing side) of the product according to the processing method of the present invention! (%), FIG. 9 is a diagram showing an example of a drawing die with a built-in heater, and FIG. 10 is a diagram showing an example of a state in which the material (blank) is heated. DESCRIPTION OF SYMBOLS 10... Base, 11... Punch, 12... Upper die, 13... Lower die, 14... Press stand, 15...
...Product, 16...4-f heater with thermostat, 20...Ridanel heater, 21...Material (blank). Patent Applicant Fujitsu Limited Patent Application Agent Patent Attorney ± 1 Akira Ki Patent Attorney Kazuyuki Nishidate Patent Attorney 1) Yukio Patent Attorney Akiyuki Yamaguchi, Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Introduction to the song (manufactured number: 9)

Claims (1)

[Claims] 1. In the press working of quasi-aunutenitic stainless steel sheets, the amount of chemical components of the stainless steel sheets is detected in advance,
A processing temperature corresponding to the amount of chemical components, the target performance and processing amount of the product to be processed is set, the stainless steel plate and press mold are preheated or cooled to the set temperature, and then the stainless steel plate is pressed. By performing the processing, the amount of processing-induced martensite induced in the 76V steel processing process is controlled to a desired value, so that the target performance of the processed product can always be consistently obtained. Pressing method for quasi-austenitic stainless steel copper plate