JP2012131002A - Steel blasting material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem in conventional blasting materials for blasting treatment having a chemical composition comprising 0.6 to 1.4 mass% C, 0.3 to 1.6 mass% Si, 0.3 to 1.3 mass% Mn, ≤0.05 mass% P, ≤0.05 mass% S, and the balance of Fe and inevitable impurities, wherein a finished blasted surface is uneven or the blasting material is rapidly consumed because large variations are present in a metal structure or hardness or the like of individual blasting materials.SOLUTION: A steel blasting material includes a chemical composition comprising: 0.7 to 1.2 mass% C, 0.4 to 1.5 mass% Si, 0.35 to 1.2 mass% Mn, ≤0.05 mass% P, ≤0.05 mass% S, and the balance of Fe and inevitable impurities.

Description

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

Steel-based projectiles are generally manufactured using cast steel consisting of about 1% C, and are widely used in applications such as deburring of iron-based metal materials, removal of deposits, and removal of oxide films, including casting sand removal. in use.
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 manufactured by being crushed into particles by the cooling medium, there is a problem in that 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: 0.05% or less, the balance being Fe and inevitable impurities A blasting projection material having a chemical composition consisting of: 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 having a small variability in quality (hardness, density, metal structure) and a stable polishing ability by optimizing chemical components including the content of trace components (impurities). And

The present invention has been made to achieve the above object.
The blasting projection material of the present invention contains, in mass%, C: 0.7 to 1.2%, Si: 0.4 to 1.5%, Mn: 0.35 to 1.2%, P: 0.05% or less, S: 0.05% or less, The balance is characterized by having a chemical composition comprising Fe and inevitable impurities.

The blasting projection material of the present invention preferably contains Al: 0.04 to 0.12% by mass. Furthermore, it is preferable to contain Cr: 0.1-1.2% by mass%. In addition, it is preferable to contain B: 0.001 to 0.05% by mass.

Furthermore, the blast treatment projection material of the present invention contains, in mass%, C: 0.85-1.15%, Si: 0.6-1.0%, Mn: 0.6-1.0%, P: 0.03% or less, and S: 0.03% or less. can do.
The blasting projection material of the present invention preferably contains Al: 0.04 to 0.12% by mass. Furthermore, it is preferable to contain Cr: 0.1-1.2% by mass%. In addition, it is preferable to contain B: 0.001 to 0.05% by mass.

Furthermore, it is possible to contain Mo and W in a total of 0.1 to 0.5% by mass, or 0.05 to 0.5% in total of V, Nb, and Ti in mass%.

  As apparent from the above description, the present invention contains, in mass%, C: 0.7 to 1.2%, Si: 0.4 to 1.5%, Mn: 0.35 to 1.2%, P: 0.05% or less, and S: 0.05% or less. Further, the balance has a chemical composition composed of Fe and inevitable impurities, so that the variation in quality can be reduced by narrowing the composition range of each element.

Moreover, by containing Al: 0.04-0.12% by mass%, a shape can be improved and an internal defect (vacancy) can be reduced. Furthermore, hardenability can be improved by containing Cr: 0.1-1.2% by mass%. Moreover, hardenability can further be improved by containing B: 0.001-0.05% by mass%.

  Moreover, by containing C: 0.85-1.15%, Si: 0.6-1.0%, Mn: 0.6-1.0%, P: 0.03% or less, and S: 0.03% or less in mass%, it prevents deterioration of mechanical strength. it can.

Moreover, by containing Al: 0.04-0.12% by mass%, a shape can be improved and an internal defect (vacancy) can be reduced. Furthermore, hardenability can be improved by containing Cr: 0.1-1.2% by mass%. Moreover, hardenability can further be improved by containing B: 0.001-0.05% by mass%.

  Furthermore, by containing Mo and W in a total of 0.1 to 0.5% by mass, the hardenability is improved and the tempering hardness is improved. If it is less than 0.1%, there is no effect, and if it exceeds 0.5%, there is no cost merit and the toughness also decreases.

Further, by containing 0.05 to 0.5% in total by mass of V, Nb and Ti, there is an effect of refining crystal grains and improving toughness. O. If it is less than 5%, there is no effect, and if it exceeds 0.5%, carbides increase, and the toughness is reduced.

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 that the raw material was a desired component and melted using an experimental high-frequency melting furnace having 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 Hv 440 to 460. The shots subjected to the heat treatment were sieved and the size of φ1 mm (the one that 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.
For porosity, when shot particles were embedded in a resin and polished, and the particle cross section was observed with a magnifying glass, the ratio of shot particles in which the area occupied by the voids was 10% or more of the cross sectional area was determined. . 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 a major axis of the shot particle twice or more the minor axis was obtained. 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 the average value of 20 effective measured values was obtained.

Regarding the shot life, an impact crushing test specified in SAE (Society of Automotive Engineers, Inc.) J-445 was conducted. That is, 100 g of the above φ1 mm shot is put into a test apparatus, repeatedly collided with a wear-resistant cast iron target at a speed of 60 m / s, and the crushed shot is removed by sieving at every fixed number of collisions and the weight of the remaining shot is increased. 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.

  Examples 1 to 3 were prepared by adjusting P and S to be 0.04 to 0.05% with respect to the chemical composition of claim 1, and particularly investigating the effects of C, Si, and Mn. Si and Mn are close to the lower limit, Example 2 is a composition where C, Si, and Mn are close to the upper limit, and Example 3 is the most common composition. 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 in which C, Si, and Mn did not satisfy the lower limit of the composition of claim 1, the porosity and non-spherical particle ratio increased, and the life ratio was greatly reduced. This is because C, Si, and Mn are low, so that the deoxidation effect at the time of dissolution is insufficient, and defects such as vacancies increase. Further, in Comparative Example 2 in which C, Si, and Mn exceed the upper limit of the composition of claim 1, the life ratio is particularly greatly reduced. This is because, since the amount of C is large, carbide (Fe ₃ C) is easily formed during water atomization, and particles in which carbide that could not be decomposed by heating during quenching are mixed.

  In Example 4, the influence of Al was investigated. When Al contained in the composition range shown in claim 2 was included, 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 in which Al exceeded the upper limit of the composition range shown in claim 2, the non-spherical particle ratio increased and the life ratio also decreased although the porosity was low. 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.

  Example 5 is an investigation of the effect of Cr, and when Al is contained within the composition range shown in claim 2 and further containing Cr within the composition range shown in claim 3, the porosity, non-spherical The particle ratio was significantly reduced, the life ratio was slightly improved, and good results were obtained.

  On the other hand, in Comparative Example 4 in which Cr exceeded the upper limit of the composition range shown in claim 3, the non-spherical particle ratio increased and the life ratio decreased in comparison with 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 to reduce toughness.

  Example 6 is an investigation of the effect of B, Al is contained within the composition range shown in claim 2, and Cr is contained within the composition range shown in claim 3, and further the composition range shown in claim 4. In the case of containing B, 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 where B exceeded the upper limit of the composition range shown in claim 4, the result was close to Example 6, but considering the cost, the composition range shown in claim 4 was sufficiently effective. It is possible to obtain

＜試験例2＞

<Test Example 2>

In this test example, the effects of C, Si, Mn, P, S and Mo, W, V, Nb, and Ti were 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, the influence of each element on the porosity and non-spherical particle ratio could be confirmed, so in this test example, only the result of the life ratio is shown.

  In Examples 7-8, with regard to the chemical composition of claim 5, after adjusting P, S to be 0.03% or less, the effects of C, Si, Mn were investigated, Example 7 was C, Si and Mn are compositions close to the lower limit, and Example 8 is a composition where C, Si, and Mn are close to the upper limits. The life ratios of the samples of Examples 7 to 8 all exceeded 100, and the effects of reducing P and S, which are harmful elements for steel, and making C, Si and Mn more preferable ranges were observed.

In Example 9, the influence of Al on the chemical composition of claim 5 was investigated, and the life ratio was improved as compared with Example 4 in Table 1. This is estimated to be an effect of adjusting P and S low.
On the other hand, in Comparative Example 6 exceeding the Al composition range shown in Claim 6, the life ratio was lowered as in Comparative Example 3 in Table 1.

  Example 10 is an investigation of the effect of Cr, and when Al is contained within the composition range shown in claim 6 and further containing Cr within the composition range shown in claim 7, the life ratio is slightly improved. Good results were obtained.

  On the other hand, in Comparative Example 7 in which Cr exceeded the upper limit of the composition range shown in Claim 7, the life ratio was lowered as compared with 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 to reduce toughness.

  Example 11 is an investigation of the effect of B, Al is contained in the composition range shown in claim 6, and Cr is contained in the composition range shown in claim 7, and further the composition range shown in claim 8. In the case of containing B, the life ratio was improved and the best result was obtained.

  On the other hand, in Comparative Example 8 where B exceeded the upper limit of the composition range shown in claim 8, the result was close to Example 11, but considering the cost, the composition range shown in claim 8 is sufficiently effective. It is possible to obtain

  Example 12 is an investigation of the effects of Mo and W, Al is contained within the composition range shown in claim 6, and Cr is contained within the composition range shown in claim 7, and B is further claimed. In the case where it is contained within the composition range shown in FIG. 9, when Mo and W are contained within the composition range shown in claim 9, the life ratio is further improved as compared with Example 11, and the best results are obtained.

  On the other hand, in Comparative Example 9 in which the sum of Mo and W exceeded the upper limit of the composition range shown in Claim 9, the life ratio was somewhat reduced compared to Example 12, but the cost was reduced. In consideration, it is possible to obtain a sufficient effect within the composition range shown in claim 9.

  Example 13 is an investigation of the effects of V, Nb, and Ti.Al is contained within the composition range shown in claim 6, and Cr is contained within the composition range shown in claim 7, and B is further charged. In the case where it is contained within the composition range shown in Item 8, when it contains V, Nb, and Ti in the composition range shown in Claim 10, the highest life ratio was obtained and the best result was obtained. It is presumed that the inclusion of an appropriate amount of V, Nb, and Ti improved the microstructure of the metal and improved toughness.

  In contrast, in Comparative Example 10 in which the total amount of V, Nb, and Ti exceeded the upper limit of the composition range shown in Claim 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 (10)

Chemical composition comprising, by mass%, C: 0.7 to 1.2%, Si: 0.4 to 1.5%, Mn: 0.35 to 1.2%, P: 0.05% or less, S: 0.05% or less, the balance being Fe and inevitable impurities A blasting projection material characterized by comprising: The blasting treatment projection material according to claim 1, which contains Al: 0.04 to 0.12% by mass%. 3. The blasting projection material according to claim 2, comprising Cr: 0.1 to 1.2% by mass%. 4. The blast treatment projection material according to claim 3, which contains B: 0.001 to 0.05% by mass%. In mass%, C: 0.85-1.15%, Si: 0.6-1.0%, Mn: 0.6-1.0%, P: 0.03% or less, S: 0.03% or less, with the balance being a chemical composition consisting of Fe and inevitable impurities. A blasting projection material, comprising: 6. The blast treatment projection material according to claim 5, which contains Al: 0.04 to 0.12% by mass%. The blasting treatment projection material according to claim 6, wherein the blast treatment projection material contains Cr: 0.1 to 1.2% by mass%. The blasting treatment projection material according to claim 7, wherein B: 0.001 to 0.05% by mass. The blasting treatment projection material according to claim 1, wherein the blast treatment projection material contains Mo and W in a total of 0.1 to 0.5% by mass. The blasting treatment projection material according to claim 1, comprising 0.05 to 0.5% of V, Nb, and Ti in total by mass%.