JPH09256165A - Chemical conversion treatment of stainless steel material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently form a seizure resisting chemical conversion coating by bringing a dissimilar metal into contact with a stainless steel material and immersing them simultaneously in a treatment solution containing oxalic acid. SOLUTION: In the case where a coiled wire 1 as a stainless steel material is subjected to chemical conversion treatment, this wire is immersed together with an outer wire gauze 3 and an inner wire gauze 4, both of which are made of dissimilar metal, in a chemical conversion treatment solution of proper oxalic acid liquid conditions. Then, after treatment of high pressure water washing is performed, and wires 5 are removed and the wire gauzez 3, 4 are separated from the wire 1. Moreover, iron is most suitable used as the dissimilar metal. Because of the formation of a seizure resisting chemical conversion coating film is formed on the surface of the stainless steel material as mentioned above, pretreatment, such as pre-immersion in sulfuric acid, pre-immersion in hydrofluoric acid and nitric acid, high pressure water washing, and preheating of base material, can be omitted, and further, the coating, film capable of maintaining excellent seizure resistance even if the composition after chemical conversion treatment becomes slightly out of balance, can be formed easily with high efficiency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chemical conversion treatment method for a stainless steel material, which comprises forming a chemical conversion coating on the surface of a stainless steel material using an oxalate coating solution.

[0002]

2. Description of the Related Art Conventionally, in order to form a chemical conversion film capable of maintaining seizure resistance on the surface of a stainless steel material even if the composition balance of the chemical conversion treatment liquid is disturbed, the concentration of phosphate ion in the chemical conversion treatment liquid is increased. The method of chemical conversion treatment of stainless steel with 0.03 to 0.6 g / l is, for example, Japanese Patent Publication No. 6-
No. 72310.

[0003]

However, in such a conventional method for chemical conversion treatment of stainless steel, the concentration of phosphate ion added to the oxalic acid solution is measured for each chemical conversion treatment step, and the concentration is always kept constant. Must be managed to a value,
Therefore, there is a problem that the chemical conversion treatment is complicated, the chemical conversion treatment time is prolonged, and the overall processing efficiency of the chemical conversion treatment is deteriorated.

Further, in the above-mentioned conventional chemical conversion treatment method, in order to activate the surface of the raw material and strengthen the reaction with the chemical conversion treatment liquid, the stainless steel material is pre-soaked in sulfuric acid before starting the chemical conversion treatment. (Japanese Patent Publication No. 5-26872), it is necessary to pre-immerse in a hydrofluoric nitric acid solution, pressurize it, or preheat the base material in a warm water tank, and then immediately perform oxalic acid treatment, which makes each of these operations complicated. This is one of the causes of the deterioration of the processing efficiency as described above.

Further, since a number of such work steps are required, a number of treatment tanks for each work are arranged, which increases equipment costs and requires a large work site near the oxalic acid tank. There was a problem of becoming.

The present invention is intended to solve the above-mentioned problems, and it is possible to omit pretreatment such as sulfuric acid pre-immersion, fluorinated nitric acid pre-immersion, pressurized water, and base material preheating immediately before chemical conversion treatment with a chemical conversion treatment liquid. , A method for chemical conversion treatment of stainless steel material that can form a chemical conversion coating that maintains good seizure resistance on the surface of stainless steel material with high efficiency with simple and low-cost equipment even if the composition balance after chemical conversion treatment is slightly disturbed. The purpose is to provide.

[0007]

In order to achieve this object,
The present invention, a different metal is brought into contact with a stainless steel material to be subjected to a chemical conversion treatment, and these are immersed in a chemical conversion treatment liquid containing oxalic acid as a main component to form a seizure-resistant chemical conversion film on the surface of the stainless steel material. It is designed to be formed.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a stainless steel material and a dissimilar metal assembly structure used for carrying out the method of the present invention.
The case where a stainless steel wire rod is used as the stainless steel material is shown. In FIG. 1, (1) is a stainless steel wire supported by a hook (2), and here, a coiled one is used.

Further, (3) and (4) are outer wire meshes and inner wire meshes of one winding as dissimilar metals, which are arranged on the inner peripheral surface and the outer peripheral surface of the above-mentioned coil-shaped stainless steel wire (1). Yes, these are many contacts and are arranged so as to evenly contact the outer peripheral surface and the inner peripheral surface of the stainless steel wire (1).

The outer wire mesh (3) and the inner wire mesh (4) are bound to each other by wires (5) at a plurality of positions at both ends, and these wire meshes (3), (4) and wire ( Five)
Are in contact with the respective end faces of the stainless steel wire (1).

Then, in order to perform the chemical conversion treatment of the stainless steel wire rod (1), the stainless steel wire rod (1) together with the outer wire mesh (3) and the inner wire mesh (4) as described above is subjected to an appropriate oxalic acid solution condition. Immerse at the same time in the chemical conversion treatment solution.

Further, after this chemical conversion treatment, a pressure water post-treatment is performed, and then the wire (5) is removed to separate the outer wire mesh (3) and the inner wire mesh (4) from the stainless steel wire (1). To do. In this way, it is possible to obtain a stainless steel wire rod having the characteristics shown in Table 1, which has been subjected to the oxalate coating treatment as the chemical conversion coating treatment.

[0013]

[Table 1]

Iron is the most suitable as the above-mentioned dissimilar metal that is the wire meshes (3), (4) and the wire (5) used here, but other metals other than these have a greater ionization tendency than the treated material. If it is a metal, a sufficient adhesion effect of the oxalate film can be obtained. In order to obtain a sufficient adhesion effect, it is desirable to increase the amount of the different metals used.

Further, even if the wire mesh of the dissimilar metal is brought into contact with only one of the inner and outer circumferences of the stainless steel wire (1) but not both, an almost sufficient oxalate coating treatment can be realized.

According to experiments, SUH660 was used as the processing material.
(Φ8.0) and 3807 g (trade name) of 3807 M (trade name) as a chemical conversion treatment liquid, 3807 C (trade name) of 8.
5g / l, AC16 (trade name) 4.5g / l Parker solution (coating solution) and φ1.6 wire (smoothing material) as the dissimilar metal (shown as P in Table 1) ),
When the above-mentioned chemical conversion treatment is carried out separately when a wire mesh woven with a wire of φ0.9 is used as the dissimilar metal (indicated by Q in Table 1) and no dissimilar metal such as wire is used, the result is It is as shown in Table 1 above.

In Table 1, T is used as a bending test for the treated material.
The evaluation criteria of the treated film when P is bent so that the interior angle is 60 ° are classified into four stages of A, B, C and D. The observed portion of each wire for evaluation was the convex portion of the bent TP, and after bending, lightly rubbing with a cloth in order to remove the coating film peeled off and attached to the convex portion.

The above evaluation criterion A is a case where the film is firmly attached. The evaluation criterion B is when the coating is almost attached but feels thin as a whole, or when the coating is firmly attached but the amount of peeling of the coating when bending is large or when the coating is partially peeled.

Further, the evaluation criterion C is that the coating is substantially attached, but the coating is slightly peeled off when bent as a whole or the coating peeling amount is large. Also, the evaluation standard D is
This is the case where the coating is completely peeled off.

From this experimental effect, when different metals are in contact with each other, the oxalate film formation is better than in the case where they are not contacted, and when the contact amount of different metals is large, it is better than when there is less contact. It was confirmed that

That is, by carrying out the method of the present invention,
The contact of dissimilar metals can improve the adhesion of the oxalate coating to the treated material, which improves the seizure resistance and eliminates the need to add phosphoric acid to the chemical conversion treatment liquid as in the past, thus controlling the phosphoric acid concentration. The work of can be avoided.

Further, there is no need for the conventional pretreatment such as sulfuric acid pre-soaking, hydrofluoric nitric acid pre-soaking, pressurized water, preheating of the base material, etc., and chemical conversion treatment may be carried out within 8 hours after pickling.
Even if each of the above pretreatments is performed, there is no need to perform oxalic acid treatment immediately after the treatment. Therefore, it is possible to reduce the chemical conversion treatment process and equipment, and further reduce the space occupied by the equipment.

[0023]

As described above, according to the invention of claim 1, different metals are brought into contact with the stainless steel material to be subjected to the chemical conversion treatment, and these are immersed in the chemical conversion treatment solution containing oxalic acid as a main component. Since a galvanic resistant chemical conversion coating is formed on the surface of the above stainless steel material, pretreatment such as sulfuric acid pre-immersion, hydrofluoric nitric acid pre-immersion, pressurized water, base metal pre-heating just before chemical conversion treatment with the chemical conversion treatment liquid is omitted. Even if the composition balance after the chemical conversion treatment is slightly disrupted, the effect that the chemical conversion coating that maintains good seizure resistance can be easily and efficiently formed on the surface of the stainless steel material is obtained.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an assembly structure of a stainless steel material and a dissimilar metal used for carrying out the chemical conversion treatment method of the present invention.

[Explanation of symbols]

 1 Stainless steel wire rod 3 Outside wire mesh (dissimilar metal) 4 Inner wire mesh (dissimilar metal)

Claims (1)

[Claims] 1. A stainless steel material to be subjected to a chemical conversion treatment is brought into contact with a dissimilar metal, and these are simultaneously immersed in a stainless steel treatment liquid containing oxalic acid to form a seizure-resistant chemical conversion coating on the surface of the stainless steel material. A method for chemical conversion treatment of a stainless steel material, which comprises forming.