JPS6016489B2 - Manufacturing method for hot-rolled steel with excellent vibration damping properties - Google Patents

Description

[Detailed Description of the Invention] Recently, pollution problems have been occurring frequently due to vibrations generated by machine tools, industrial machinery, etc., noise generated by bridges, transportation systems, etc., but the present invention solves such noise and vibrations. The present invention relates to a method for manufacturing hot rolled steel materials with excellent vibration damping properties that are effective for reducing vibrations.

A material with excellent vibration damping characteristics is a ferromagnetic type material.

That is, when a ferromagnetic material is magnetized, a so-called magnetostriction phenomenon occurs in which the material stretches in the direction of magnetization. Conversely, it can be said that materials that exhibit magnetostriction always have the property of becoming magnetized by applying strain. When such a material is subjected to vibration or impact, vibrational strain waves propagate within the material, resulting in time-varying oscillatory magnetization.

In a ferromagnetic material, the size and direction of the magnetic domain change during the magnetization process,
Along with this, the domain walls at the boundaries of the magnetic domains move. The magnetization-magnetic field strength curve, known as the magnetization curve, forms a well-known hysteresis loop that consumes energy proportional to the area of the loop, which is used to move this wall. In other words, the movement of domain walls always involves energy consumption. Since this energy is supplied from distorted waves, a part of the vibrational distortion energy is consumed as magnetic energy. Because such energy consumption is rare, in order to obtain the material, the domain walls must be sufficiently developed and the walls must be easily movable. To achieve this, it is necessary not to leave strain in the material and to reduce the amount of interstitial elements C and N in the solid state. Further, it is necessary that the ferrite grain size is approximately 5 or less in terms of grain size number. The present invention is based on the above findings, and aims to provide a method for producing a rolled steel material that has a microstructure in which the wall is easily movable and has excellent vibration damping properties. That is, the present invention is based on CO. 003~0.050, S
io. 10-0.45%, Mnl. 05-2.50%, Crl. 0-20.0% and S.

Finishing A: 0.010-9-0%, Ti: 0.01-0.09
%, Cuo. After heating the steel containing one or more of 05 to 1.50% and the remainder substantially consisting of Fe to a temperature of 1150°C or higher and 1270°C or lower, rolling is carried out at a finishing temperature of 9.
It is characterized by the fact that by applying a thickness reduction rate of 10% or more with a thickness of 00qo or more and 105,000 or less and allowing it to cool, it is possible to obtain a rolled steel material that generally has mechanical properties comparable to SS materials and has excellent vibration damping properties. If necessary, by holding the above-mentioned steel material after roughening in a temperature range of 600 qo or more and 900 qo or less until the value of T (200 qo) becomes 21.0 × 1 pi or more (where T: absolute temperature ( K), t:
It is characterized by being able to impart even greater vibration damping characteristics over time (hr).

The reasons for limiting the range of steel components in the method of the present invention will be described below.

Since C increases the strength, it is necessary to contain it in an amount of 0.003% or more, but if it exceeds 0.050%, it deteriorates the damping characteristics.

Si is added in an amount of 0.10% or more for the purpose of deoxidizing and increasing strength, but if it is added in an amount exceeding 0.45%, the rutting property deteriorates.

Mn fixes the harmful effect of S, which clouds hot cracks, as MnS and renders it harmless. It is also effective in improving strength and toughness, and for this purpose, it is necessary to add 1.05% or more.

However, addition of more than 2.50% deteriorates damping performance.
When Cr is added in an amount of 1.0% or more, the hard port N that inhibits the movement of the domain wall is fixed as CrN, thereby improving source control performance.

However, if it exceeds 20%, hot cracking and deterioration of rutting properties occur. By adding 0.010% or more of SoSoA, solid solution N, which is harmful to the movement of the wall, is fixed as A,
Although it improves vibration damping properties, if it exceeds 9.0%, it becomes difficult to melt and deteriorates the solubility.

When Ti is added in an amount of 0.01% or more, TIN or TIC is generated and the strength is increased by dispersion strengthening. However, if added in excess of 0.09%, toughness will deteriorate. When adding Ti, the ferrite grain size does not become coarse during rolling, so it is desirable to carry out the bowl anchoring treatment in a temperature range of 600 to 900 qC.By adding 0.05% or more of Cu, It is effective for solid solution strengthening or for increasing strength by agitating the precipitation of Cu.

However, addition of more than 1.50% deteriorates vibration damping performance. Next, in hot rolling, it is necessary to eliminate segregation and make the crystal grains sufficiently coarse by heating before rolling. In the method of the present invention, the heating temperature for rolling is set to 1150 qo or higher,
The aim is to coarsen the crystal grains and reduce polarization.

At temperatures lower than 1150 pm, AZN will not harden sufficiently.
The particle size does not become coarse.

Also, heating above 1270 pm will significantly deteriorate the surface properties of the slab due to oxidation, so the temperature should be set at 1270 pm or less.

The rolling process is applied at a reduction rate of 10% or more because it is necessary to eliminate internal defects in the steel material, and the upper limit is not particularly limited, but should be applied in consideration of the capacity of the rolling mill, the target thickness of the finished plate, etc. It is advisable to determine the thickness reduction rate appropriately.

At this time, if the rolling finishing temperature is too low, the crystal grains become finer and the vibration damping performance deteriorates. In the method of the present invention, since the C content of the steel is extremely low as described above, the austenite transforms into a ferrite single-phase structure, and unlike general inter-rolled steel materials that normally contain C, it does not transform into ferrite + pearlite, so the ferrite produced The grains are originally coarse, but by setting the finishing temperature of rolling to 900 qo or more, the austenite grains subjected to the rolling process become coarse due to stress relief annealing, and the ferrite grains that undergo further transformation also become coarse. However, it is impossible to exceed 1050 oo at the actual hot rolling speed, and it inevitably becomes less than 1050 qo due to temperature drop.

Figure 1 shows the relationship between rolling finishing temperature and ferrite grain size in steel with the above-mentioned composition range limited in the present invention. The lower the rolling finishing temperature, the larger the ferrite grain size number and the smaller the grain size. (hatched area), the processed structure remains.

By setting the finishing rolling temperature to 900 oo or more, the ferrite grain size number becomes 5 or less, which can provide good damping properties to the damping steel material. The method of the present invention can obtain excellent properties as a restricted rolled steel material as described above, but in addition,
By performing phosphorous annealing treatment in the temperature range of 00 to 900°C, the crystal grains are further coarsened, various strains are removed, and a steel material with high vibration damping properties can be obtained.

FIG. 2 shows the temperature and holding time range of the moth blunt in the method of the present invention. This means that a branding temperature of 900°C is about 30 seconds or more, 800°C is about 20 minutes or more, 700°C is about 3 hours or more, and 600°C is about 1 year or more. The effects of the present invention will be described below with reference to Examples.

Table 1 shows the chemical composition of the test steel.

Table 1 Next, Table 2 shows the physical properties of hot-rolled steel products made from steel with the components listed in Table 1. In the manufacturing method column of Table 2, the heating temperature is the pre-rolling heating temperature, and the degree of working is the heating temperature. Thickness reduction rate in inter-rolling, finishing temperature indicates hot rolling finishing temperature, age anchor indicates scorching hammer after rolling, A and mouth correspond to the rolling treatment conditions in the method of the present invention, and C indicates before rolling. The heating temperature and rolling finish temperature are unsuitable for the conditions of the method of the present invention.

The internal friction value shown in Table 2 is an index of damping characteristics, and the higher the value, the better the damping characteristics.

Steels A to S all satisfy the limiting conditions for steel components in the present invention, but as shown in Tables 1 and 2, the rolled steel material C, whose treatment conditions are not compatible with the method of the present invention, is a material that is compatible with the method of the present invention. The internal friction value is much lower than that of rolled steel. In addition, T in the comparative example is SM41 village, but as shown in Table 2, the internal friction value is extremely low under all treatment conditions, indicating poor vibration damping characteristics. It is clear that the rolled material has sufficient strength and quality as a structural steel comparable to SM41 material, and also has extremely excellent vibration damping properties.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the relationship between the finishing temperature of rolling and the ferrite grain size of steel having a composition range in the method of the present invention. FIG. 2 is a range diagram of the temperature and holding time of the ant hammer in the method of the present invention. Groove 1 figure 2 figure

Claims (1)

[Claims] 1 C 0.003-0.050%, Si 0.10-0.
45%, Mn1.05-2.50%, and Cr1.0
~20.0% and SolAl0.010~9.0%, Ti
1 of 0.01-0.09%, Cu0.05-1.50%
After heating a steel containing one or more kinds of seeds and the remainder consisting of Fe to a temperature of 1150°C or more and 1270°C or less, rolling and pressing is performed at a finishing temperature of 900°C or more and 1050°C or less and a thickness reduction rate of 10% or more. A method for producing hot-rolled steel materials with excellent vibration damping properties, characterized by rolling and cooling. 2 C0.003-0.050%, Si0.10-0.
45%, Mn1.05-2.50%, and Cr1.0
~20.0% and SolAl0.010~9.0%, Ti
1 of 0.01-0.09%, Cu0.05-1.50%
After heating the steel containing one or more species and the remainder essentially consisting of Fe to 1150°C or more and 1270°C or less, rolling is performed at a finishing temperature of 900°C or more and 1050°C or less at a thickness reduction rate of 10% or more. After cooling, T(20+logt)≧21×10^3 in the temperature range of 600℃ or higher and 900℃ or lower
However, T: absolute temperature (°K), t: time (hr
) A method for producing hot rolled steel with excellent vibration damping properties.