JP5777201B2 - Steel projection material - Google Patents

Description

The present invention relates to a steel-based projection material that has small variations in quality (hardness, density, metal structure) and has a stable scouring ability.

Steel-based projectiles are generally manufactured using cast steel consisting of about 1% C, and are widely used for deburring of iron-based metal materials, removal of deposits, and removal of oxide films, including casting sand removal. It is used.
Other projection materials used for such applications include cut wires cut from hard steel wires, stainless cut wires manufactured by cutting stainless steel wires, stainless shots manufactured by atomizing stainless cast steel with water, etc. However, steel shot is the most widely used blasting material that can be manufactured at the lowest cost.
However, for example, a cut wire is manufactured by cutting a uniform material such as a wire, so it has the feature that there is little variation in components, hardness, metal structure, etc. Since the particles are crushed into particles by the cooling medium, the cooling history of individual particles (shots) varies, and the same variation occurs in the heat treatment process such as quenching and tempering. For this reason, there are problems in that the finish of the blasted surface is uneven as compared with the cut wire, and the shot is consumed quickly.

Conventionally, in mass%, C: 0.6 to 1.4%, Si: 0.3 to 1.6%, Mn: 0.3 to 1.3%, P: 0.05% or less, S : A blasting projection material containing 0.05% or less and the balance having a chemical composition composed of Fe and inevitable impurities was used. Even with such a wide variation in components, it performed well for processing purposes such as removing sand from castings and removing oxides from steel sheets, but due to the large variations in the metal structure and hardness of individual shots, blasting There are problems that the surface finish is uneven and that the projection material is consumed quickly.

It is an object of the present invention to provide a projection material in which the variability in quality (hardness, density, metal structure) is small and the cleaning ability is stable by optimizing chemical components including the content of trace components (impurities). And

The present invention has been made to achieve the above object.
The blast treatment projection material of the present invention is in mass%, C: 0.96 to 1.0%, Si: 0.82 to 0.88%, Mn: 0.92 to 0.99%, Al: 0 0.08-0.11%, Cr: 0.22-0.68%, P: 0.02-0.04%, S: 0.02-0.04%, B: 0.003-0.04 % , With the balance having a chemical composition consisting of Fe and inevitable impurities.

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As is apparent from the above description, the present invention is, in mass%, C: 0.96 to 1.0%, Si: 0.82 to 0.88%, Mn: 0.92 to 0.99%, Al: 0.08-0.11%, Cr: 0.22-0.68%, P: 0.02-0.04%, S : 0.02-0.04 %, B: 0.003-0. By containing 04% and the balance having a chemical composition composed of Fe and inevitable impurities, the compositional range of each element was narrowed, thereby making it possible to reduce quality variations.

Further, by containing Al: 0.08 to 0.11 % by mass%, the shape can be improved and internal defects (vacancies) can be reduced. Furthermore, hardenability can be improved by containing Cr: 0.22 to 0.68 % by mass%. Moreover, hardenability can be improved further by containing B: 0.003-0.04% by mass%.

In addition mass%, C: 0.96 ~ 1.0% , Si: 0.82 ~ 0.88%, Mn: 0.92~0.99%, P: 0.02~0.04%, S : By containing 0.02 to 0.04 %, a decrease in mechanical strength can be prevented.

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Hereinafter, test examples (Examples / Comparative Examples) performed for confirming the effects of the present invention will be described.
<Test Example 1>

    In this test example, steel scrap, Fe-Si, Fe-Mn, Fe-Cr, Fe-B, pure aluminum, carburized to investigate the effects of C, Si, Mn, P, S, Al, Cr, B The raw material composition was adjusted so as to be a desired component using the raw material as a raw material and melted using an experimental high-frequency melting furnace with an iron equivalent melting amount of 100 kg. The melting temperature was 1640-1680 ° C., and steel shots were produced by the water atomization method. The obtained shot was dried and heated to 850 ° C. and held for 1 hour, followed by water quenching, and further tempered so that the shot had a hardness of Hv440 to 460. The shots subjected to the heat treatment were sieved and a size of φ1 mm (passed through the 1.18 mm sieve and remained on the 1.00 mm sieve) was taken out and evaluated for quality and the like. The results are shown in Table 1.

The porosity, non-spherical particle ratio, and hardness were measured by the methods defined in JIS-Z0311.
Regarding the porosity, when shot particles were embedded in a resin and polished, and the cross section of the particles was observed with a magnifier, the ratio of shot particles in which the area occupied by the voids was 10% or more with respect to the cross sectional area was obtained . The number of shot particles observed was 100.
Regarding the non-spherical particle ratio, when the shot particles were spread on a glass flat plate and observed with a magnifying glass, the ratio of the particles having the major axis of the shot particle twice or more the minor axis was determined. The number of shot particles observed was 100.
Regarding the hardness, shot particles were embedded in a resin and polished, and the Vickers hardness of the particle cross section was measured. The test load was 9.8 N, the load time was 12 seconds, and an average value of 20 effective measured values was obtained.

With respect to the life of the shot, an impact crushing test defined by SAE (Society of Automotive Engineers, Inc.) J-445 was performed. That is, 100 g of the above-mentioned φ1 mm shot is put into a test apparatus, and repeatedly collided with a wear-resistant cast iron target at a speed of 60 m / s. Measurements were made until the residual shot was below the initial 30%. The value obtained by integrating the curve showing the relationship between the number of collisions and the residual shot weight ratio obtained by this test was defined as the life value. The life ratio shown in Table 1 is a ratio when the life value of Example 3, which is a general composition, is set to 100. The larger the life ratio value, the better the durability. Yes.
Regarding the chemical composition, the shots themselves were analyzed by emission spectroscopy.

    In Examples 1 to 3, P and S are adjusted to 0.04 to 0.05%, and in particular, the influence of C, Si and Mn is investigated. The samples of Examples 1 to 3 were not significantly different in terms of porosity, non-spherical particle ratio, and life ratio.

    On the other hand, in Comparative Example 1, the porosity and non-spherical particle ratio increased, and the life ratio was greatly reduced. This is because, since C, Si, and Mn are low, the deoxidation effect at the time of dissolution is insufficient, and defects such as vacancies increase. Moreover, in the comparative example 2, especially the life ratio fell significantly. This is because, since the amount of C is large, carbides (Fe3C) are easily formed during water atomization, and particles in which carbides that could not be decomposed by heating during quenching are mixed.

    In Example 4, the influence of Al was investigated. The porosity and non-spherical particle ratio were significantly reduced, and the life ratio was slightly improved. This is considered to be due to the deoxidation effect by Al.

    On the other hand, in Comparative Example 3, although the porosity was low, the non-spherical particle ratio increased and the life ratio also decreased. This is considered to be a result of the oxide being formed on the surface of the molten metal when Al is excessive, which deteriorates the shape by inhibiting the surface tension.

    In Example 5, the influence of Cr was investigated, and the porosity and non-spherical particle ratio were remarkably reduced, and the life ratio was slightly improved, and good results were obtained.

    On the other hand, in Comparative Example 4, the non-spherical particle ratio increased and the life ratio decreased compared to Example 5. When Cr is excessive, it is presumed that, as in the case of Al, oxides formed on the surface of the molten metal are increased and the shape is deteriorated, and Cr carbides are easily formed and the toughness is lowered.

    In Example 6, the influence of B was investigated, and the porosity and non-spherical particle ratio were the lowest, the life ratio was the highest, and the best results were obtained.

On the other hand, in Comparative Example 5, the result was close to that of Example 6. However, considering the cost, it is possible to obtain a sufficient effect with the B amount of Example 6 .

<Test Example 2>

In this test example, the influence of C, Si, Mn, P, S and Mo, W, V, Nb, and Ti was investigated.
The sample preparation method and evaluation method are the same as in Test Example 1. The results are shown in Table 2.
In Test Example 1, since the influence of each element on the porosity and non-spherical particle ratio could be confirmed, this test example shows only the result of the life ratio.

    Examples 7-8 investigate the influence of C, Si, and Mn after adjusting P and S to be 0.03% or less. The life ratios of the samples of Examples 7 to 8 all exceeded 100, and the effects of reducing P and S, which are elements harmful to steel, and making C, Si and Mn more preferable ranges were observed.

In Example 9, the influence of Al was investigated, and the life ratio was improved as compared with Example 4 in Table 1. This is estimated to be the effect of adjusting P and S low.
On the other hand, in Comparative Example 6, the life ratio decreased as in Comparative Example 3 in Table 1.

    In Example 10, the influence of Cr was investigated, and the life ratio was slightly improved, and good results were obtained.

On the other hand, in Comparative Example 7, the life ratio was lower than that in Example 10.
When Cr is excessive, it is presumed that, as in the case of Al, oxides formed on the surface of the molten metal are increased and the shape is deteriorated, and Cr carbides are easily formed and the toughness is lowered.

    In Example 11, the influence of B was investigated. The life ratio was improved and the best result was obtained.

On the other hand, in Comparative Example 8, the result was close to Example 11, but it is possible to obtain a sufficient effect with the amount of B of Example 11 in consideration of the cost.

    In Example 12, the influence of Mo and W was investigated, and the life ratio was further improved as compared with Example 11, and the best result was obtained.

    On the other hand, in Comparative Example 9, the life ratio was somewhat reduced as compared with Example 12, but it is possible to obtain a sufficient effect in the composition range shown in Example 12 in consideration of cost. is there.

    In Example 13, the effects of V, Nb, and Ti were investigated. The highest life ratio was obtained and the best result was obtained. By including appropriate amounts of V, Nb, and Ti, it is presumed that the metal structure is refined and the toughness is improved.

On the other hand, in Comparative Example 10, the life ratio was significantly reduced as compared with Example 13.
It was confirmed that when V, Nb, and Ti are excessive, these elements form coarse carbides and reduce the life ratio.

Claims (1)

C: 0.96-1.0%, Si: 0.82-0.88%, Mn: 0.92-0.99%, Al: 0.08-0.11%, Cr: 0.22 to 0.68%, P: 0.02 to 0.04%, S: 0.02 to 0.04% , B: 0.003 to 0.04%, the balance being Fe and inevitable A blasting projection material, characterized by having a chemical composition comprising impurities.