JPS6216267B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing knife iron.

Knife iron has been used for many years as a base material for household knives, carpenter's tools, and agricultural tools, but its production is generally done by semi-smelling pig iron in a type of reverberatory furnace called a charcoal furnace or a coal-fired paddle furnace. It has been manufactured using the traditional smelting method, which involves melting, oxidizing and removing the carbon in the pig iron, extracting the paste-like material, and then forging it. They are no longer manufactured.

However, this knife iron contains a large number of layers of non-metallic inclusions that are mainly composed of pure iron oxide, so when it is honed with a whetstone, it becomes extremely soft and has remarkable free-cutting properties. It also has properties such as good forge weldability due to its porous nature, and excellent electrochemical cathodic corrosion resistance due to the oxide in the iron base, making it an essential base material for various cutlery tools. Currently, those skilled in the art are only able to meet this demand by dismantling aging iron bridges and towers and salvaging sunken ships.

Therefore, in order to manufacture inexpensive knife iron on an industrial scale, the inventor of the present invention has conducted various researches and found that by subjecting soft iron thin plates to surface oxidation treatment to form an oxide scale layer, stacking these layers and rolling or forging. discovered that it is possible to produce a dispersed metal composite material in which an oxide scale layer is dispersed in a fine uniform layer in a rolled or forged material, and that it has physical properties comparable to knife iron produced by conventional methods, and has developed the present invention. It was completed.

That is, the object of the present invention is to laminate soft iron thin plates with an oxide scale layer formed on their surfaces, or to laminate them with oxide scale plates or oxide scale wool interposed between the soft iron thin plates, and to weld and seal the peripheral edges of the laminated plates. Provided is a method for producing knife iron, which is characterized in that the iron is then subjected to hot rolling or forging to give a rolling reduction or processing rate of 30% or more at a forge welding temperature, thereby dispersing the oxide scale layer in a fine uniform layer. It's about doing.

Generally, knife iron has C0.03~0.05% and Si0.03~0.10.
%, Mn0.10~0.30%, P0.010~0.030%, S0.002
Because it has a composition of ~0.020% and the balance iron,
As the starting material, extremely soft iron or enameled steel plate (hereinafter simply referred to as soft iron thin plate unless otherwise specified) suitable for the above-mentioned composition is used.

In the laminate, it is preferable that a plurality of oxide scale layers are inserted into the iron base, and the surfaces of soft iron thin plates are laminated by oxidation treatment, or the soft iron ultrathin plates corresponding to the oxide scale layers are substantially oxidized by oxidation treatment. The entire structure is formed by laminating a layer of oxide scale (hereinafter referred to as an oxide scale plate) inserted between thin sheets of soft iron, and welding and sealing the entire periphery.

The oxide scale layer has a porous structure in which oxides such as Fe ₂ O ₃ , Fe ₃ O ₄ and FeO are uniformly dispersed.

The depth of the oxide scale layer is determined in relation to the plate thickness, and for a plate thickness of 3 to 5 mm, 0.5 to 1 mm is practically appropriate.

When inserting an oxide scale plate, use a scale plate of 0.3 to 1 mm, and when using oxide scale wool, use scale wool that has been oxidized with ignition to make approximately 50% or more iron oxide. .

The forge welding conditions for the laminate are determined depending on the oxide scale layer and the chemical and physical properties of the soft iron sheet, but the initial reduction rate or working rate is 30% at the forge welding temperature.
It has been found that by carrying out the above process, the built-in oxide scale is completely finely fractured, and the desired bonding is achieved through complex dispersion accompanying the diffusion bonding of iron, and the crystal grains are integrated in the recrystallization process. ing. In addition, when inserting an oxide scale plate, it is preferable that the reduction ratio at the forge welding temperature is 35% or more.
Thereafter, it is rolled or forged to a predetermined thickness according to a conventional method.

The present invention will be explained below based on Examples.

Example 1 As shown in Fig. 1, a piece of extremely soft iron for cutlery (SAE1008) 5 x 100 x 700 mm was heated in a heavy oil furnace 3 at 1000°C for 10 minutes, and an oxidation scale of about 0.25 to 0.5 mm was formed on the surface. form a layer. This oxidized plate 7
After stacking the sheets, covering them with a 5 mm thick cover sheet, and sealingly welding the entire periphery to form the laminate W,
Heated to a temperature of 1100℃ and subjected to hot rolling 4 to 45mm
The steel is rolled down to 10mm and forge welded to obtain knife iron. In this rolling process, the first pass is 45mm.
When the steel is rolled down to 31.5mm, the built-in oxide scale is completely finely fractured, and the iron is bonded by diffusion bonding, and the crystals are made uniform in the recrystallization process.
The state is shown in the cross-sectional micrograph of FIG.

Example 2 As shown in Figure 2, extremely soft iron for cutlery (SAE1008) 5 x 100 x 700 mm1 and decarburized steel plate for enamel SPP JIS G3133 (1981) 0.5 x 100 x
Using 700 mm2 as a material, the iron plate 2 is heated for 10 minutes in an oxygen-rich furnace 3 to form an oxide scale layer of approximately 0.2 mm on each surface, thereby forming an oxide scale plate 2.
These 5 oxide scale plates were stacked by inserting them between 6 pieces of extremely soft steel so as not to break each plate, covered with a 5 mm thick cover sheet, and welded around the entire periphery to form a 42.5×
A laminate W′ of 110×710 mm is formed. This is 1100
It is heated to a temperature of 35°C, and a rolling reduction of 35% or more is applied at first, and finally rolled to a thickness of 15mm to obtain knife iron.

Test Example A knife was manufactured by a conventional method using the knife iron obtained in Examples 1 and 2 as a base material for the blade, and the blade was manufactured using dismantled iron from iron bridges, etc. as the base material, and the free machinability and forge weldability were evaluated. As a result of comparative tests, it was confirmed that all of the new products were good, and the same effect as that of knife iron, which was conventionally manufactured using the old iron manufacturing method, was obtained.

[Brief explanation of the drawing]

Fig. 1 is a process explanatory diagram showing a manufacturing example according to the present invention, Fig. 2 is a process explanatory diagram showing another manufacturing example, and Fig. 3 is a process explanatory diagram showing a manufacturing example according to the present invention.
The figure is a cross-sectional micrograph showing the internal structure of the knife iron obtained by the method of Example 1. 1... Soft iron thin plate (very soft iron), 2... Oxidation scale plate, 3... Oxidation treatment furnace, 4... Rolling equipment.

Claims (1)

[Claims] 1 Laminate soft iron thin plates with a large amount of oxide scale layer on the surface, or laminate them with oxide scale plates or oxide scale wool interposed between the soft iron thin plates, and after welding and sealing the periphery of the laminated plates, hot Subjected to rolling or forging treatment, at least 30°C at forge welding temperature
A method for producing knife iron, which is characterized by providing a rolling reduction or processing rate of % or more and dispersing an oxide scale layer in a fine uniform layer.