JPH0765144B2 - Stainless steel for cold forging - Google Patents

Description

TECHNICAL FIELD The present invention relates to a ferritic stainless steel, and more particularly to a stainless steel for cold forging in which the ferritic stainless steel has improved corrosion resistance, magnetic properties, free-cutting properties, and the like. Is.

(Prior Art and Problems to Be Solved) As the soft magnetic material, various materials are used depending on the application, such as pure iron, silicon iron, electromagnetic stainless steel, and permalloy.

Of these, stainless steels for electromagnetics, such as 13Cr and 18Cr, are mainly used for electromagnetic valves, relay iron cores, etc. due to their excellent magnetic properties and corrosion resistance. Some of this kind of electromagnetic stainless steel contains appropriate amounts of silicon and aluminum for the purpose of improving magnetic properties, and a small amount of ships, calcium, tellurium, selenium, etc. are added to impart machinability. There is also free-cutting stainless steel. However, as a stainless steel for electromagnetics, not only the magnetic properties and corrosion resistance but also the demand for further improvement in workability is not necessarily satisfied.

The present invention has been made in order to meet such a request, and an object thereof is to provide a stainless steel for cold forging which can improve corrosion resistance, formability or machinability without impairing magnetic properties. To do.

(Means for Solving the Problems) In order to achieve the above object, the present invention has been made by attempting to control the so-called impurity amount together with the addition of alloying elements.

That is, the stainless steel for cold forging according to the present invention is C
≤0.08%, Si: 0.1-3.0%, Mn≤0.5%, Cr: 8-18% and
Mo ≦ 3%, Ti: 0.01-1%, Nb: 0.01-1%,
One or more of Zr: 0.01 to 1% and V: 0.01 to 1%, and S ≦ 0.015%, N ≦ 0.05%, O ≦ 100pp
Restricted to m, and further containing Al ≤ 0.5% as a base component, and optionally Pb: 0.03 to 0.3%, C
a: 0.002-0.02%, Te: 0.01-0.2%, Bi: 0.002-0.02%
And Se: 0.03 to 0.3%, or one or more of them are added.

The present invention will be described in detail below based on examples.

First, the reasons for limiting the components of the steel of the present invention will be shown.

C is preferably as small as possible in order to improve corrosion resistance and magnetic properties, but 0.08% is made the upper limit in consideration of various melting conditions.

Si has the effect of improving the magnetic characteristics, especially the saturation magnetic flux density (B ₃₀ ), and increasing the electric resistance. For that, 0.1-3.0
% Must be added.

Mn is added as a deoxidizer, but if it is too much, it deteriorates the workability, so 0.5% is made the upper limit.

Cr is an important component for ensuring corrosion resistance. If it is less than 8%, its effect cannot be obtained, and if it is added in excess of 18%, the effect saturates, resulting in poor hot workability and high cost. Therefore, it is added in the range of 8 to 18%.

Mo is effective in improving the corrosion resistance, but if it is too much, it causes deterioration of hot workability, so it is added at 3% or less.

Ti, Nb, Zr, and V have the effect of fixing C, N, etc. in the steel to improve the magnetic properties, especially lowering the coercive force, so one or more of them are added as necessary. To do. When added, Ti: 0.01-1%, Nb :: 0.01-1%, Zr: 0.01-1
%, V: 0.01 to 1%.

S, N and O are contained as so-called impurities in steel, but S
Deteriorates the cold workability, so it is necessary to control it to 0.015% or less. Further, by controlling N to be 0.05% or less, it is effective in improving magnetic characteristics such as a decrease in coercive force.
If O is present in a large amount, cracks will form from the oxide, which will deteriorate the cold forgeability. Therefore, in order to prevent this and reduce the coercive force (Hc), it is necessary to regulate the content to 100 ppm or less.

In addition to the above basic components, the following elements can be added as required.

Al has the effect of improving the magnetic properties, and further has the effect of increasing the electrical resistance. When it is added, the upper limit is 0.5%, and if it is too large, the hot workability deteriorates.

Pb, Ca, Te, Bi and Se can improve the machinability without impairing the magnetic properties, and when added, one or more of them are Pb: 0.03 to 0.3%, Ca: 0.002 to 0.02%, Te: 0.0
It is added in the range of 1 to 0.2%, Bi: 0.002 to 0.02%, Se: 0.03 to 0.3%. If the amount of each component exceeds the upper limit, hot workability deteriorates.

(Example) A sample steel having the chemical composition (wt%) shown in Table 1 was melted,
After forging, hot forging and hot rolling were performed to manufacture a round bar material having a diameter of 60 mm.

Next, after subjecting each round bar material to annealing treatment at 850 ° C. for 4 hours, magnetic properties and corrosion resistance were examined, and machinability was also examined for some of them, and the results shown in Table 1 and FIG. 1 were obtained. It was

The corrosion resistance was evaluated by the degree of corrosion by conducting an exposure test in which the above sample was left in the atmosphere for 100 days. Also,
Machinability is 0.084 mm / re for feed using HSS tool (SKH4)
v, depth of cut 1.0 mm, cutting speed 60 m / min, cutting was performed under the conditions of using a cutting fluid, and the flank wear width was evaluated.

As can be seen from Table 1, all of the sample steels of the present invention examples (No. 1 to 10, 13) have excellent magnetic properties such as coercive force and saturation magnetic flux density (B ₃₀ ), and also have excellent corrosion resistance. While Mo
Comparative example (No. 11) that does not contain Ti has poor corrosion resistance,
The comparative example (No. 12) not containing r and V has high coercive force and poor magnetic properties.

Further, as shown in FIG. 1, it is clear that the machinability is improved in the example of the present invention to which the free-cutting element is added, and even in that case, the magnetic characteristics are not degraded.

(Effects of the Invention) As described in detail above, according to the present invention, since Mo is particularly added, Ti, Tb, Zr or V is added and the amount of impurities is further regulated, the magnetic characteristics can be improved. At the same time, corrosion resistance can be improved, and further machinability and workability can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing the machinability of the example of the present invention, showing the relationship between the cutting time and the flank wear width.

Claims (4)

[Claims] 1. In weight% (hereinafter the same), C ≦ 0.08%, S
i: 0.1 to 3.0%, Mn ≤ 0.5%, Cr: 8 to 18% and Mo ≤ 3%, Ti: 0.01 to 1%, Nb: 0.01 to 1%, Zr: 0.01 to
1% and V: 0.01 to 1% out of 0.01 to 1% or more, and S ≦ 0.015%, N ≦ 0.05%, O ≦ 100 ppm, and the balance substantially Fe. Stainless steel for cold forging. 2. C ≦ 0.08%, Si: 0.1-3.0%, Mn ≦ 0.5%,
Cr: 8-18%, Mo ≦ 3% and Al ≦ 0.5%, and Ti: 0.
01 ~ 1%, Nb: 0.01 ~ 1%, Zr: 0.01 ~ 1% and V: 0.01 ~
1% or more of 1% or more and S ≦ 0.015
%, N ≦ 0.05%, O ≦ 100 ppm, the balance is substantially
Stainless steel for cold forging, which is made of Fe. 3. C ≦ 0.08%, Si: 0.1-3.0%, Mn ≦ 0.5%,
Cr: 8-18% and Mo ≤ 3%, Ti: 0.01-1%, N
b: 0.01 to 1%, Zr: 0.01 to 1% and V: 0.01 to 1%, or one or more of them, Pb: 0.03 to 0.3%, Ca: 0.002 to 0.
02%, Te: 0.01-0.2%, Bi: 0.002-0.02% and Se: 0.03
~ 0.3% and one or more of
Stainless steel for cold forging, characterized in that ≦ 0.015%, N ≦ 0.05%, and O ≦ 100ppm, with the balance consisting essentially of Fe. 4. C ≦ 0.08%, Si: 0.1-3.0%, Mn ≦ 0.5%,
Cr: 8-18%, Mo ≦ 3% and Al ≦ 0.5%, and Ti: 0.
01 ~ 1%, Nb: 0.01 ~ 1%, Zr: 0.01 ~ 1% and V: 0.01 ~
One or more of 1% and Pb: 0.03 to 0.3%, C
a: 0.002-0.02%, Te: 0.01-0.2%, Bi: 0.002-0.02%
And Se: containing one or more of 0.03 to 0.3%, regulating S ≦ 0.015%, N ≦ 0.05%, and O ≦ 100 ppm, with the balance being essentially Fe. Stainless steel for cold forging.