JP2021076588A - Method for quantitatively identifying environmentally-friendly lead-free silicon brass with high strength, high plasticity and free-cutting property - Google Patents

Abstract

To provide a method that can be executed simply, and quantitatively identifies a silicon brass alloy with high strength, high plasticity and free-cutting property at low cost.SOLUTION: A method comprises: conducting a quasi-static tensile mechanical property test; determining quasi-static tensile yield stress σs and elongation δ for silicon brass alloys with different zinc equivalents; calculating cutting dynamic yield stress σd; with the zinc equivalent of the silicon brass alloy taken on a horizontal axis, and the quasi-static tensile yield stress σs, the elongation δ, and the cutting dynamic yield stress σd taken on a vertical axis, plotting a change tendency diagram of the quasi-static tensile yield stress σs, the elongation δ and the cutting dynamic yield stress σd with respect to the zinc equivalent; and acquiring an alloy with high strength, high plasticity and free-cutting property in which the quasi-static tensile yield stress σs is 100 MPa to 250 MPa, the elongation δ is 40% to 15%, and the dynamic yield stress σd is smaller than the quasi-static tensile yield stress σs.SELECTED DRAWING: Figure 3

Description

The present invention relates to lead-free silicon brass, specifically, a method for quantitatively identifying environment-friendly lead-free silicon brass having high strength, high plasticity, and free-cutting property, and manufactures an environment-friendly lead-free brass alloy and its parts. Belongs to the field.

Brass is widely used as one of important engineering materials in various fields such as bathroom equipment, household hardware, heat sinks, electronic devices, and low temperature pipes. Generally, brass has 1 to 3 wt. % Lead is added. Lead alone can act as a softening mass point during alloy cutting, and contributes to the improvement of brass chip cutting resistance and adhesion resistance. For this reason, lead brass is called free-cutting brass. However, lead brass is becoming more and more strict due to environmental regulations because lead has an adverse effect on the environment and human health. Therefore, attention is being paid to the development of lead-free brass such as silicon brass, brass bismuth, brass magnesium, and brass graphite. Among these developed lead-free brass, silicon element is abundant worldwide and environmentally friendly, so silicon brass is considered to be an economically and environmentally feasible alternative to lead brass. Has been done. However, the correlation between the machinability of silicon brass and its mechanical properties is unknown.

The main constituent phases of silicon brass microstructures are roughly classified into α phase (face-centered cubic), β phase (body-centered cubic), and γ phase (complex cubic). Due to their crystallographic features, size and content, the effects of various phase compositions on the mechanical properties of silicone brass are well recognized. In particular, at room temperature, the α phase exhibits lower microhardness and higher plasticity than the β phase. Therefore, as the content of the α phase in silicon brass increases, the hardness and tensile strength decrease, and the elongation increases. Conversely, at high temperatures, the α phase has a higher microhardness than the β phase. Further, the γ phase is more brittle than the α phase and the β phase, and the elongation decreases when the γ phase is present in the brass matrix. Based on the above viewpoint, we conclude that in complex extreme conditions with certain high temperature variables and other variables (eg metal cutting process), silicon brass will have different mechanical properties with respect to room temperature conditions. Can be attached.

In the cutting of plastic brass, continuous long chips are easily entangled or wrapped, so that the chip cutting force plays an important role in smooth cutting process. In particular, the α phase and β phase of brass have a great influence on the chip forming characteristics of brass. For example, the β phase is advantageous for chip destruction in brass processing, and the α phase is advantageous for producing long strip-shaped chips (Non-Patent Document 1). Brass having an α + β phase results in a spiral tip, but brass having a complete β phase tends to produce a spiral tip and a tubular tip (Non-Patent Document 2). α + β brass has an excellent chip cutting force due to its non-uniform microstructure and a moderate microhardness difference between the α phase and the β phase (Non-Patent Document 3). These findings provide useful guidance for understanding the chip cutting power of silicon brass. However, in the above research, there is no choice but to qualitatively evaluate the chip cutting force of the brass alloy based on the macro chip morphology by microstructure analysis and static mechanical property test.

However, silicon brass alloys obtained by different formulations and manufacturing processes are difficult to distinguish in shape, for example, low-strength high-plastic hard-to-cut alloys, high-strength low-plastic hard-to-cut alloys and high-strength high-plastic free-cutting alloys. Although there is virtually no distinction in shape, it is practically very different. While high-strength, high-plastic free-cutting alloys have extremely important value, low-strength, high-plastic, hard-to-cut alloys and high-strength, low-plastic, hard-to-cut alloys do not yet have excellent value in practical use. .. Therefore, it is important to quantitatively identify lead-free silicon brass, which has high strength, high plasticity, and free-cutting property and is environmentally friendly.

J. Inst. Met. 69 (1940/41) 65-79 J. Mater. Process. Tech. 170 (2005) 441-447 Mater. Sci. Eng. A 723 (2018) 296-305

An object of the present invention is to qualitatively evaluate the chip cutting force of a silicon brass alloy based on a macro chip morphology. Therefore, due to the deficiency of the conventional cutting technique, high-strength, high-plastic, free-cutting, environment-friendly lead-free silicon brass By controlling the chip cutting force by associating the geometrical morphological parameters of the silicon brass alloy chip with the cutting dynamic mechanical properties, it is difficult to identify the chip effectively. To establish a quantitative identification method for free-cutting lead-free silicon brass, and to effectively identify high-strength, high-plastic free-cutting alloys.

Metal cutting is a highly non-linear plastic deformation process characterized by high temperature, high strain rate and instantaneousness. Under these extreme dynamic conditions, the strength of materials properties are considered to have properties that are clearly different from the static mechanical properties at room temperature. Therefore, in order to adjust the machinability of silicon brass, it is more preferable to establish the relationship between the fine structure and the dynamic characteristics under the cutting conditions. Usually, the dynamic mechanical properties are measured using a Split Hopkinson Pressure Bar technique with a strain rate of up to ¹⁰ 4 / s. In addition, the stress-strain model of the material being studied can be determined from the material flow stress measured by this technique. However, this operating process is relatively complex, requires high technical skills, is not cost effective, and requires adjustment and validation of corresponding stress-strain models for different materials. On the other hand, based on Mechant's cutting theory (Eng.Fract.Mech.76 (2009) 2711-2730), machining or cutting itself can be used as an alternative technique for dynamic mechanical property testing of materials. Although its effectiveness in testing average dynamic fracture plasticity and yield strength of polymers and plastic metal materials has been demonstrated, it has not been used to identify the overall performance of silicon brass alloys.

The present invention controls the chip cutting force by associating the geometrical morphological parameters of the brass chip with the cutting dynamic dynamics characteristics. Specifically, the cutting theory is based on the geometric feature quantification parameters of the chip. _{In combination with quantification, the dynamic yield stress σ d} of silicon brass with different alloy components (different zinc equivalents / different microstructures) is calculated, and the dynamic yield stress σ _d drops sharply according to the alloy zinc equivalent. Therefore, the range of silicon brass components that facilitate chip cutting is determined, and the silicon brass in this component range has comprehensive properties such as free-cutting property, high strength, and plasticity.

Quantitative identification method of lead-free silicon brass that has high strength, high plasticity, free-cutting property and is environmentally friendly, including the following steps.
1) Semi-static tensile yield stress σ _s and elongation δ test A quasi-static tensile mechanical property test was performed on a silicon brass alloy rod having a zinc equivalent of 38% to 49%, and a stress-strain curve was obtained to obtain silicon having a different zinc equivalent. Determine the quasi-static tensile yield stress σ _s and elongation δ for brass alloys.
2) Calculation of dynamic yield stress σ _d A cutting test was conducted on a silicon brass alloy with a zinc equivalent of 38% to 49%, chips were sampled, and silicon brass alloys with different zinc equivalents were cut by a cutting force model based on Mechant. Calculate the cutting dynamic yield stress σ _d in the case.
3) Quantitative identification of silicon brass alloy The horizontal axis is the zinc equivalent of the silicon brass alloy, and the vertical axis is the quasi-static tensile yield stress σ _s , elongation d, and cutting dynamic yield stress σ _d. A change tendency diagram of tensile yield stress σ _s , elongation d, and cutting dynamic yield stress σ _d was created, and based on the change tendency diagram, a silicon brass alloy was used, and quasi-static tensile yield stress σ _s was less than 100 MPa, elongation d. Is more than 40% and the dynamic yield stress σ _d is larger than the quasi-static tensile yield stress σ _s. Low-strength, high-plastic difficult-to-cut alloy, quasi-static tensile yield stress σ _s is more than 250 MPa, and elongation δ is less than 15%. and dynamic yield stress sigma _d is quasi-static tensile strength greater than the yield stress sigma _s low plasticity flame cutting alloys, quasi-static tensile yield stress sigma _s is 100MPa～250MPa, elongation δ is 40% to 15%, It is classified into three types of high-strength, high-plastic free-cutting alloys in which the dynamic yield stress σ _d is smaller than the quasi-static tensile yield stress σ _s.

In order to further realize the object of the present invention, a method for producing a brass alloy having a different zinc equivalent in step 1) uses Cu, Zn, Si, and Al elements as Cu: 56 to 66 wt. %, Zn: 33 to 42 wt. %, Si: 0.4 to 1.5 wt. %, Al: 0.2 to 1.5 wt. t% and B: 0.003 to 0.01 wt. %, Ti: 0.03 to 0.06 wt. It is preferable that the mixture is blended in a mass% of%, the zinc equivalent X% in all the components of the brass alloy is 39 to 49%, and the microstructure is the α + β phase.

（ここで、Ｘ％：亜鉛当量、Ｃ_Ｚｎ：合金添加純亜鉛含有率、Ｃ_Ｃｕ：合金添加純銅含有率、ΣＣ_ｉＫ_ｉ：合金でＣｕ、Ｚｎを除く全ての合金元素の含有率Ｃ_ｉと亜鉛当量係数Ｋ_ｉとの積の総和）により亜鉛当量を算出することが好ましい。 Design the phase composition by zinc equivalent regulation, formula

(Wherein, X%: zinc _{equivalents, C Zn:} alloying pure zinc _{content, C Cu:} alloying pure copper content, ΣC _i K _i: content of all alloy elements excluding Cu, and Zn in the alloy _{C i} it is preferable to calculate the zinc equivalent by the sum of the product of the zinc equivalent coefficient K _i).

In step 2), J. G. It is preferred _{to use the test scheme developed by William to calculate the cutting dynamic yield stress σ d} when cutting silicon brass alloys with different zinc equivalents.

The cutting test in step 2) is performed on a CNC lathe equipped with a cutting force measuring device, the cutting sample is a cylindrical rod, the cutting tool material is a commercially available WC-8Co tool, and the value of the feed rate f is changed as a machining parameter. , It is preferable that the value of the feed rate f is 0.05 to 0.3 mm / r based on the usual cutting parameters of the brass alloy.

（ここで、ｈ_ｃ／ｓｉｎφ：せん断面の長さ、ｈ_ｃ：切削層の厚み、φ：シリコン黄銅サンプルのせん断角、Ｋ_ｂ：材料の破壊靭性、ｗ_ｃ：切削幅、Ｆ_ｃ：主切削力、Ｆ_ｔ：送り抵抗）から切削動的降伏応力σ_ｄを決定し、
前記の力バランス方程式を

に変換し、
Ｆ_ｃ／ｗ_ｃ−（Ｆ_ｔ／ｗ_ｃ）ｔａｎφ及び（ｈ_ｃ／２）（ｔａｎφ＋１／ｔａｎφ）の値を算出し、
Ｆ_ｃ／ｗ_ｃ−（Ｆ_ｔ／ｗ_ｃ）ｔａｎφ及び（ｈ_ｃ／２）（ｔａｎφ＋１／ｔａｎφ）の変化関係をプロットして線形フィッティングし、傾きを切削動的降伏応力σ_ｄとし、
シリコン黄銅サンプルのせん断角φを、式

（ここで、γ_０：切削工具のすくい角、Λ_ｈは

から決定される切削変形係数、ｈ_ｃｈ：平均チップ厚み）に従って算出することが好ましい。 Force balance equation

(Here, h _c / sin φ: length of shear surface, h _c : thickness of cutting layer, φ: shear angle of silicon brass sample, K _b : fracture toughness of material, w _c : cutting width, F _c : main The cutting dynamic yield stress σ _d is determined from the cutting force ( _{Ft: feed resistance).}
The above force balance equation

Convert to
Calculate the values of F _c / w _c − (F _t / w _c ) tan φ and (h _c / 2) (tan φ + 1 / tan φ).
The change relationship of F _c / w _c − (F _t / w _c ) tan φ and (h _c / 2) (tan φ + 1 / tan φ) is plotted and linearly fitted, and the slope is defined as the cutting dynamic yield stress σ _d .
The shear angle φ of the silicon brass sample is calculated by the formula.

(Here, γ ₀ : rake angle of cutting tool, Λ _h is

It is preferable to calculate according to the cutting deformation coefficient (h _{ch: average chip thickness) determined from.}

（ここで、Ｈ：鋸歯状チップの最大高さ、ｈ_ｓ：鋸歯の高さ）を簡単化することによって取得されることが好ましい。 The value of the serrated tip, such as the tip thickness h _{ch, is}

(Here, H: maximum height of the sawtooth tip, h _s : height of the sawtooth) is preferably obtained by simplifying.

The thickness h _{c of the} cutting layer is preferably equal to the feed f value in the cylindrical turning test.

The cutting width w _c is preferably equal to _{the relief amount ap} of the cutting edge in the cylindrical turning test.

In step 3), the high-strength, high-plastic free-cutting alloy is preferably used for manufacturing bathroom equipment, household hardware, heat sinks, electronic devices, and low-temperature pipelines.

The dynamic yield stress σ _d of the present invention is determined by J. G. Using the test scheme developed by Villain, it is calculated based on Mechant's cutting force model, that is, the component force acting on the shear plane of FIG. The insert is a chip generated from a brass sample collected by a chip collector mounted on a lathe. Ten to twenty chips are randomly selected, _{the relevant chip geometry parameters such as chip thickness h ch} are measured, and finally averaged to determine the characteristic parameters of the individual chips.

_{The region where the dynamic yield stress σ d} related to the quantitative identification of the silicon brass alloy in step 3) of the present invention decreases is a value smaller than the quasi-static yield stress σ _s. In the region where the dynamic yield stress σ _d decreases, the corresponding silicon brass alloy has comprehensive properties such as high strength and high plastic free cutting property. When the cutting dynamic yield stress σ _d is reduced to less than the quasi-static yield stress σ _{s of the} material, it is advantageous to obtain a free-cutting alloy. The silicon brass alloy corresponding to the high-strength, high-plastic free-cutting region has comprehensive properties such as high strength, high plasticity, and free-cutting property, and the zinc equivalent corresponding to the region has excellent comprehensive characteristics. This is the alloy component region of. Silicone brass alloys with excellent overall properties are used in the manufacture of bathroom equipment, household hardware, heat sinks, electronics and low temperature pipelines, but the use of alloys in other areas is severely limited.

The present invention has the following advantages and effects as compared with the prior art.
1. 1. The present invention quantitatively evaluates the chip cutting force of a silicon brass alloy material by associating the geometrical morphological parameters of the metal alloy chip with the cutting dynamic mechanical properties, and is easy to implement and low cost. Overcome the drawback that conventional identification methods that take into account the dynamic extreme conditions of material cutting engineering require the establishment of stress-strain models.
2. The present invention establishes a method for quantitatively identifying the comprehensive properties (high-strength, high-plastic free-cutting property) of a silicon brass alloy, and provides a strong reference for the design of a novel silicon brass alloy. A method for designing the composition of characteristics can be provided.
3. 3. When the cutting dynamic yield stress σ _{d according} to the present invention is reduced to less than the quasi-static yield stress σ _{s of the} material, it is advantageous to obtain a free-cutting silicon brass alloy. This test method can also be applied to the free-cutting performance and overall performance tests of other metal alloy materials.

It is a figure which shows the characteristic of the geometric characteristic parameter of a serrated tip. It is a Mechant cutting force model figure at the time of cutting a metal alloy. When the cutting speed v _c = 90 m / min in the examples, the quasi-static tensile yield stress σ _s , elongation δ, and cutting dynamic yield stress σ _d of silicon brass alloys having different zinc equivalents are shown in the change tendency diagram with respect to the zinc equivalent. is there.

Optimal form for carrying out the invention

In order to better understand the present invention, the present invention will be further described below together with examples and drawings, but the embodiments of the present invention are not limited thereto.

[Example]
A method for quantitatively identifying lead-free silicon brass, which has high strength, high plasticity, and free-cutting property and is environmentally friendly, includes the following steps.

により算出される。ここで、Ｃ_Ｚｎは、合金添加純亜鉛含有率であり、Ｃ_Ｃｕは、合金添加純銅含有率であり、ΣＣ_ｉＫ_ｉは、合金中のＣｕ、Ｚｎ以外の全ての合金元素の含有率Ｃ_ｉと亜鉛当量係数Ｋ_ｉとの積の総和（ｉは、合金元素の番号を表す）である。各元素のＫ_ｉは、銅合金関連マニュアルにより調べることができ、Ｓｉ元素及びＡｌ元素のＫ_ｉは、それぞれ１０及び６である。 (1) Preparation of Silicon Brass Alloy Cu, Zn, Si, and Al elements are blended in mass% of the five alloy numbers A, B, C, D, and E shown in Table 1, and an intermetallic compound modifier and crystal. 0.005% by mass B and 0.05 wt. As a grain micronizing agent. % Ti is added and cast to obtain a tubular silicon brass alloy. Design the phase composition according to the zinc equivalent rule, the zinc equivalent (X%) is the formula

Is calculated by. _{Here, C Zn} is an alloy added pure zinc _{content, C Cu} is an alloy added pure copper content, .SIGMA.C _i K _i is, Cu in the alloy, the content of all alloy elements other than Zn C the sum of the product of the _i and zinc equivalent coefficient K _i (i represents the number of alloying elements) is. _{K i} of each element may be determined by the copper alloy related documentation, _{K i} of Si element and Al element is 10, and 6, respectively.

As the zinc equivalent increased from 39.2%, 42.7%, 45.3%, 46.9% to 48.4% by X-ray diffraction analysis, the phase composition of the silicon brass alloy changed from the α + β two phases. The zinc equivalent of all components that change to a pure β phase is 39-49%, indicating that the microstructure uses the β phase as a matrix and that granular or lumpy α phases are embedded in the β phase matrix. Is done.

(2) Semi-static tensile mechanical property test National standards for the produced zinc equivalents of 39.2%, 42.7%, 45.3%, 46.9% and 48.4% silicon brass alloy rods, respectively. A quasi-static tensile mechanical property test is performed in accordance with GB / T288-2002 to obtain the stress-strain curve, and the corresponding quasi-static tensile yield stress σ _s and elongation δ are obtained from the stress-strain curve. 66 MPa and 42.1%, 95 MPa and 48.8%, 147 MPa and 29.5%, 213 MPa and 13.1%, 257 MPa and 9.5%, respectively. As shown in Table 1, Table 1 is a table of elemental composition, phase content, quasi-static tensile yield stress σ _s , and elongation δ of silicon brass alloys having different zinc equivalents in the examples. Here, the component data is by metal spectroscopic analysis, and the phase composition is by XRD test.

(3) Cutting test Cutting force measuring device (9265-A1, Kistler Group) for the produced zinc equivalents of 39.2%, 42.7%, 45.3%, 46.9% and 48.4% silicon brass alloys. , Swizerland), a CNC lathe (CA6150i, DMTG Co., China) was used to perform a cutting test, and the cutting sample was a φ35 × 120 m cylindrical rod. Cutting tool materials, rake angle γ ₀ = 4 °, the clearance angle α ₀ = 3 °, the inclination angle lambda _s = 0 °, side cutting edge angle _K r = 90 °, geometric, such as edge radius _R n = 1 mm It is a commercially available WC-8Co (Shu Kongo Stone Sword Tool Co., Ltd., China) having characteristic parameters. The cutting parameters in the cutting test are cutting speed v _c = 90 m / min, feed speed f = 0.1 mm / r, and cutting depth a _p = 0.5 mm. Twenty chips are collected by a chip collector attached to a lathe, and the geometry of the chips such as the _{average chip thickness h ch} of silicon brass alloys with different zinc equivalents, the maximum height H of the serrated _{tip, and the height h s of the serrated tip.} The scientific characteristic parameters are measured by a scanning electron microscope. As shown in Table 2, using the above CNC lathe, cutting force measuring device, WC-8Co tool, and cutting parameters, the feed rate f was changed to 0.15 mm / r, and cutting tests were performed on silicon brass alloys with different zinc equivalents. And sample the chips and measure the geometric characteristic parameters of the chips such as the _{average chip thickness h ch of} different zinc equivalents of silicon brass alloy, the maximum height H of the sawtooth tip, the height h _{s of the sawtooth, and table.} Shown in 2. _{Table 2 shows the characteristic parameters required for calculating the cutting dynamic yield stress σ d} of the silicon brass alloys having different zinc equivalents in Examples 1 to 5 and the calculation results thereof.

に従って算出される。ここでγ_０は、切削工具のすくい角であり、Λ_ｈは、

で決定される切削変形係数であり、ｈ_ｃｈは、チップ厚みであり、チップのトポグラフィ特性を観察することによって直接測定される。ｈ_ｃは、切削層の厚みであり、円筒旋削試験における送りｆの値に等しい。鋸歯状チップが発生する場合、鋸歯状チップの厚みｈ_ｃｈの等価値は、

を簡単化することによって取得される。ここで、図１に示すように、Ｈは、鋸歯状チップの最大高さであり、ｈ_ｓは、鋸歯の高さである。以上の計算から、ある切削速度におけるある亜鉛当量のシリコン黄銅合金のせん断角φを求める。 _{(4) Calculation of cutting dynamic yield stress F c} / w _c- when cutting silicon brass alloys with different zinc equivalents using the Williams cutting process material dynamic yield stress test method based on Mechant's cutting force model. The values of (F _t / w _c ) tan φ and (h _c / 2) (tan φ + 1 / tan φ) are calculated, specifically, calculated as follows, and the necessary related characteristic parameters are as follows.
Based on the geometrical properties of the chip, the shear angle φ of the silicon brass sample is

It is calculated according to. Here, γ ₀ is the rake angle of the cutting tool, and Λ _h is

It is a cutting deformation coefficient determined by, h _ch is a chip thickness, and is directly measured by observing the topographic characteristics of the chip. h _c is the thickness of the cutting layer and is equal to the value of the feed f in the cylindrical turning test. When a serrated tip is generated, the equal value of _{the thickness h ch of the serrated tip is}

Obtained by simplifying. Here, as shown in FIG. 1, H is the maximum height of the sawtooth tip, and h _s is the height of the sawtooth. From the above calculation, the shear angle φ of a silicon brass alloy having a certain zinc equivalent at a certain cutting speed is obtained.

が得られる。ここで、σ_ｄは、動的降伏応力であり、ｈ_ｃ／ｓｉｎφは、せん断面の長さであり、Ｋ_ｂは、材料の破壊靭性であり、ｗ_ｃは、円筒旋削試験における切刃の逃げ量ａ_ｐに相当する切削幅であり、Ｆ_ｃは、主切削力であり、Ｆ_ｔは、送り抵抗である（Ｂ．Ｗａｎｇ ｅｔ ａｌ．Ｉｎｔ．Ｊ．Ｍａｃｈ．Ｔｏｏｌ．Ｍａｎｕ．７３（２０１３） １-８）。更に、上記式を以下の式、即ち切削力とせん断とワークの動的力学性能との相関関係に変換する。

各々の切削層の厚みｈ_ｃについて、切削試験により、対応するチップ厚みｈｃｈ、主切削力Ｆ_ｃ及び送り抵抗Ｆ_ｔを求め、対応する主切削力Ｆ_ｃ及び送り抵抗Ｆ_ｔを表２に示す。これにより、更にＦ_ｃ／ｗ_ｃ−（Ｆ_ｔ／ｗ_ｃ）ｔａｎφと（ｈ_ｃ／２）（ｔａｎφ＋１／ｔａｎφ）の値を算出する。最終的に、Ｆ_ｃ／ｗ_ｃ−（Ｆ_ｔ／ｗ_ｃ）ｔａｎφと（ｈ_ｃ／２）（ｔａｎφ＋１／ｔａｎφ）の変化関係をプロットして線形フィッティングして得られた直線の傾きを切削動的降伏応力σ_ｄとする。 Based on Mechant's cutting force model, J.M. G. Using the test scheme developed by William, the dynamic yield stress σ _d when cutting silicon brass is calculated. Specifically, the cutting force model of Mechant, which is the component force acting on the shear surface in FIG. 2, is analyzed, and the equation is calculated from the force balance of the shear surface.

Is obtained. Here, σ _d is the dynamic yield stress, h _c / sin φ is the length of the sheared surface, K _b is the fracture toughness of the material, and w _c is the cutting edge of the cutting edge in the cylindrical turning test. The cutting width corresponds to the relief amount _{ap , F c} is the main cutting force, and F _t is the feed resistance (B. Wang et al. Int. J. Mac. Tool. Manu. 73 (2013). ) 1-8). Further, the above equation is converted into the following equation, that is, the correlation between the cutting force, the shear, and the dynamic dynamic performance of the work.

For the thickness h _c of each cutting layer, the corresponding chip thickness hch, main cutting force F _c and feed resistance F _t are obtained by a cutting test, and the corresponding main cutting force F _c and feed resistance F _t are shown in Table 2. .. As a result, _{the values of F c} / w _c − (F _t / w _c ) tan φ and (h _c / 2) (tan φ + 1 / tan φ) are further calculated. Finally, _{the slope of the straight line obtained by plotting the change relationship between F c} / w _c − (F _t / w _c ) tan φ and (h _c / 2) (tan φ + 1 / tan φ) and linearly fitting is cut. _{Let the} yield stress σ d.

(5) Identification of high-strength, high-plastic free-cutting alloy As shown in Fig. 3, the quasi-static tensile yield stress σ _s , elongation δ, and calculated cutting dynamic yield stress are calculated with the zinc equivalent of the silicon brass alloy as the horizontal axis. With σ _d on the vertical axis, a change trend diagram for each performance index with respect to zinc equivalent is plotted. From the figure, it can be seen that as the zinc equivalent increases, the quasi-static tensile yield stress σ _s also increases, the elongation δ decreases, and the cutting dynamic yield stress σ _d decreases once and then increases. In the region where the dynamic yield stress σ _d decreases, the value is smaller than the quasi-static yield stress σ _s, which is advantageous for the instability of thermoplasticity and the generation of serrated tips, and has free-cutting property. As a result, the silicon brass alloy has a quasi-static tensile yield stress σ _s of less than 100 MPa, an elongation δ of more than 40%, and a dynamic yield stress σ _d larger than the quasi-static tensile yield stress σ _s. Difficult-to-cut alloy, quasi-static tensile yield stress σ _s is 100 MPa to 250 MPa, elongation δ is 40% to 15%, and dynamic yield stress σ _d is smaller than quasi-static tensile yield stress σ _s. Scraping alloy, quasi-static tensile yield stress σ _s is more than 250 MPa, elongation δ is less than 15%, and dynamic yield stress σ _d is larger than quasi-static tensile yield stress σ _s. Classify into 3 types. In addition, the silicon brass alloy corresponding to the high-strength, high-plastic free-cutting region has comprehensive performance such as high strength, high plasticity, and free-cutting property, and the zinc equivalent corresponding to the region is comprehensively excellent. This is the alloy component region. Alloys in other regions are severely limited in their use. Therefore, it is important to effectively identify a high-strength, high-plastic free-cutting alloy.

Compared with the prior art, the present invention quantitatively evaluates the chip cutting ability of a silicon brass alloy material by associating the geometrical morphological parameters of the metal alloy chip with the cutting dynamic mechanical properties, and is easy to implement and low cost. It overcomes the drawback that the conventional identification method considering the dynamic extreme conditions of material cutting engineering needs to establish a stress-strain model. At the same time, the present invention establishes a quantitative identification method of high strength and high plasticity free-cutting property which is advantageous for high-performance silicon brass alloy component design, and becomes a strong reference for the design of a novel silicon brass alloy. Further, when the cutting dynamic yield stress σ _{d of} the present invention is reduced to less than the quasi-static yield stress σ _{s of the} material, it is advantageous for the instability of thermoplastics and the generation of serrated chips, and the free-cutting silicon brass. An alloy is obtained. This test method can also be applied to the free-cutting performance and overall performance tests of other metal alloy materials.

The above-described embodiment does not limit the scope of protection of the present invention, and a person skilled in the art can use the technical means of the present invention and the idea of the patent of the present invention within the scope disclosed by the present invention. All equal substitutions or modifications made are within the scope of the patent of the present invention.

(Additional note)
(Appendix 1)
A method for quantitatively identifying lead-free silicon brass, which has high strength, high plasticity, and free-cutting property and is environmentally friendly, which comprises the following steps.
1) Semi-static tensile yield stress σ _s and elongation δ test A quasi-static tensile mechanical property test was performed on a silicon brass alloy rod having a zinc equivalent of 38% to 49%, and a stress-strain curve was obtained to obtain silicon having a different zinc equivalent. Determine the quasi-static tensile yield stress σ _s and elongation δ for brass alloys.
2) Calculation of dynamic yield stress σ _d A cutting test was conducted on a silicon brass alloy with a zinc equivalent of 38% to 49%, chips were sampled, and silicon brass alloys with different zinc equivalents were cut by a cutting force model based on Mechant. Calculate the cutting dynamic yield stress σ _d in the case.
3) Quantitative identification of silicon brass alloy The horizontal axis is the zinc equivalent of the silicon brass alloy, and the vertical axis is the quasi-static tensile yield stress σ _s , elongation δ, and cutting dynamic yield stress σ _d. A change tendency diagram of tensile yield stress σ _s , elongation δ, and cutting dynamic yield stress σ _d was created, and based on the change tendency diagram, a silicon brass alloy was used, and quasi-static tensile yield stress σ _s was less than 100 MPa, elongation δ. Is more than 40% and the dynamic yield stress σ _d is larger than the quasi-static tensile yield stress σ _s. Low-strength, high-plastic difficult-to-cut alloy, quasi-static tensile yield stress σ _s is more than 250 MPa, and elongation δ is less than 15%. and dynamic yield stress sigma _d is quasi-static tensile strength greater than the yield stress sigma _s low plasticity flame cutting alloys, quasi-static tensile yield stress sigma _s is 100MPa～250MPa, elongation δ is 40% to 15%, It is classified into three types of high-strength, high-plastic free-cutting alloys in which the dynamic yield stress σ _d is smaller than the quasi-static tensile yield stress σ _s.

(Appendix 2)
The method for producing a brass alloy having different zinc equivalents in step 1) is to use Cu, Zn, Si and Al elements as Cu: 56 to 66 wt. %, Zn: 33 to 42 wt. %, Si: 0.4 to 1.5 wt. %, Al: 0.2 to 1.5 wt. t% and B: 0.003 to 0.01 wt. %, Ti: 0.03 to 0.06 wt. High strength and high plasticity according to Appendix 1, wherein the zinc equivalent X% in all the components of the brass alloy is 39 to 49%, and the microstructure is α + β phase. -A method for quantitatively identifying lead-free silicon brass that has free-cutting properties and is environmentally friendly.

（ここで、Ｘ％：亜鉛当量、Ｃ_Ｚｎ：合金添加純亜鉛含有率、Ｃ_Ｃｕ：合金添加純銅含有率、ΣＣ_ｉＫ_ｉ：合金でＣｕ、Ｚｎを除く全ての合金元素の含有率Ｃ_ｉと亜鉛当量係数Ｋ_ｉとの積の総和）により亜鉛当量を算出することを特徴とする付記２に記載の高強度・高塑性・快削性を有し環境に優しい無鉛シリコン黄銅の定量的同定方法。 (Appendix 3)
Design the phase composition by zinc equivalent regulation, formula

(Wherein, X%: zinc _{equivalents, C Zn:} alloying pure zinc _{content, C Cu:} alloying pure copper content, ΣC _i K _i: content of all alloy elements excluding Cu, and Zn in the alloy _{C i} quantitative identification friendly lead-free silicon brass environment has a high strength and high plasticity, free-cutting according to note 2, characterized in that to calculate the zinc equivalent by the sum) of the product of the zinc equivalent coefficient K _i and Method.

（ここで、σ_ｄ：動的降伏応力、ｈ_ｃ／ｓｉｎφ：せん断面の長さ、Ｋ_ｂ：材料の破壊靭性、ｗ_ｃ：円筒旋削試験における切刃の逃げ量ａ_ｐに相当する切削幅、Ｆ_ｃ：主切削力、Ｆ_ｔ：送り抵抗）が得られ、
Ｆ_ｃ／ｗ_ｃ−（Ｆ_ｔ／ｗ_ｃ）ｔａｎφと（ｈ_ｃ／２）（ｔａｎφ＋１／ｔａｎφ）の変化関係を直線でフィッティングして得られた直線の傾きを切削動的降伏応力σ_ｄとすることを含むことを特徴とする付記１に記載の高強度・高塑性・快削性を有し環境に優しい無鉛シリコン黄銅の定量的同定方法。 (Appendix 4)
In step 2), J. G. Using the test scheme developed by William, the cutting dynamic yield stress σ _d when cutting silicon brass alloys with different zinc equivalents was calculated, specifically,
Equation from the force balance of the sheared surface

(Here, σ _d : dynamic yield stress, h _c / sin φ: length of sheared surface, K _b : fracture toughness of material, w _c : cutting width corresponding to _{the relief amount ap} of the cutting edge in the cylindrical turning test. , F _c : main cutting force, F _t : feed resistance)
The slope of the straight line obtained by fitting the change relationship between F _c / w _c − (F _t / w _c ) tan φ and (h _c / 2) (tan φ + 1 / tan φ) with a straight line is defined as the cutting dynamic yield stress σ _d . The method for quantitatively identifying lead-free silicon brass, which has high strength, high plasticity, and free-cutting property and is environmentally friendly, according to Appendix 1, which comprises the above.

(Appendix 5)
The cutting test in step 2) is performed on a CNC lathe equipped with a cutting force measuring device, the cutting sample is a cylindrical rod, the cutting tool material is a commercially available WC-8Co tool, and the value of the feed rate f is changed as a machining parameter. , Has high strength, high plasticity, and free-cutting property as described in Appendix 4, characterized in that the value of the feed rate f is set to 0.05 to 0.3 mm / r based on the normal cutting parameters of the brass alloy. Quantitative identification method for environmentally friendly lead-free silicon brass.

（ここで、ｈ_ｃ／ｓｉｎφ：せん断面の長さ、ｈ_ｃ：切削層の厚み、φ：シリコン黄銅サンプルのせん断角、Ｋ_ｂ：材料の破壊靭性、ｗ_ｃ：切削幅、Ｆ_ｃ：主切削力、Ｆ_ｔ：送り抵抗）から切削動的降伏応力σ_ｄを決定し、
前記の力バランス方程式を、

に変換し、
Ｆ_ｃ／ｗ_ｃ−（Ｆ_ｔ／ｗ_ｃ）ｔａｎφ及び（ｈ_ｃ／２）（ｔａｎφ＋１／ｔａｎφ）の値を算出し、
Ｆ_ｃ／ｗ_ｃ−（Ｆ_ｔ／ｗ_ｃ）ｔａｎφ及び（ｈ_ｃ／２）（ｔａｎφ＋１／ｔａｎφ）の変化関係をプロットして線形フィッティングし、傾きを切削動的降伏応力σ_ｄとし、
シリコン黄銅サンプルのせん断角φを、式

（ここで、γ_０：切削工具のすくい角、Λ_ｈは、

から決定される切削変形係数、ｈ_ｃｈ：平均チップ厚み）に従って算出することを特徴とする付記５に記載の高強度・高塑性・快削性を有し環境に優しい無鉛シリコン黄銅の定量的同定方法。 (Appendix 6)
Force balance equation

(Here, h _c / sin φ: length of shear surface, h _c : thickness of cutting layer, φ: shear angle of silicon brass sample, K _b : fracture toughness of material, w _c : cutting width, F _c : main The cutting dynamic yield stress σ _d is determined from the cutting force ( _{Ft: feed resistance).}
The above force balance equation,

Convert to
Calculate the values of F _c / w _c − (F _t / w _c ) tan φ and (h _c / 2) (tan φ + 1 / tan φ).
The change relationship of F _c / w _c − (F _t / w _c ) tan φ and (h _c / 2) (tan φ + 1 / tan φ) is plotted and linearly fitted, and the slope is defined as the cutting dynamic yield stress σ _d .
The shear angle φ of the silicon brass sample is calculated by the formula.

(Here, γ ₀ : rake angle of cutting tool, Λ _h is

Quantitative identification of environment-friendly lead-free silicon brass having high strength, high plasticity, and free-cutting property according to Appendix 5, which is calculated according to the cutting deformation coefficient (h _{ch: average chip thickness) determined from} Method.

(Appendix 7)
The tip thickness of the sawtooth tip, h _ch, etc., is _{to simplify h ch} = H− (h _s / 2) (where H: the maximum height of the sawtooth tip, h _s : the height of the sawtooth). The method for quantitatively identifying lead-free silicon brass, which has high strength, high plasticity, and free-cutting property and is environmentally friendly, according to Appendix 6, which is obtained by.

(Appendix 8)
Quantitative identification of environmentally friendly lead-free silicon brass having high strength, high plasticity, and free turning property according to Appendix 6, wherein the thickness h _{c of the cutting layer is equal to the feed f value in the cylindrical turning test.} Method.

(Appendix 9)
The quantification of lead-free silicon brass having high strength, high plasticity, free turning property and environmental friendliness according to Appendix 6, wherein the cutting width w _{c is equal to the relief amount ap} of the cutting edge in the cylindrical turning test. Identification method.

(Appendix 10)
In step 3), the high-strength, high-plastic free-cutting alloy according to Appendix 1, wherein the high-strength, high-plastic free-cutting alloy is used for manufacturing bathroom equipment, household hardware, heat sinks, electronic devices, and low-temperature pipelines. -A method for quantitatively identifying lead-free silicon brass, which has high plasticity and free-cutting properties and is environmentally friendly.

Claims (10)

A method for quantitatively identifying lead-free silicon brass, which has high strength, high plasticity, and free-cutting property and is environmentally friendly, which comprises the following steps.
1) Semi-static tensile yield stress σ _s and elongation δ test A quasi-static tensile mechanical property test was performed on a silicon brass alloy rod having a zinc equivalent of 38% to 49%, and a stress-strain curve was obtained to obtain silicon having a different zinc equivalent. Determine the quasi-static tensile yield stress σ _s and elongation δ for brass alloys.
2) Calculation of dynamic yield stress σ _d A cutting test was conducted on a silicon brass alloy with a zinc equivalent of 38% to 49%, chips were sampled, and silicon brass alloys with different zinc equivalents were cut by a cutting force model based on Mechant. Calculate the cutting dynamic yield stress σ _d in the case.
3) Quantitative identification of silicon brass alloy The horizontal axis is the zinc equivalent of the silicon brass alloy, and the vertical axis is the quasi-static tensile yield stress σ _s , elongation δ, and cutting dynamic yield stress σ _d. A change tendency diagram of tensile yield stress σ _s , elongation δ, and cutting dynamic yield stress σ _d was created, and based on the change tendency diagram, a silicon brass alloy was used, and quasi-static tensile yield stress σ _s was less than 100 MPa, elongation δ. Is more than 40% and the dynamic yield stress σ _d is larger than the quasi-static tensile yield stress σ _s. Low-strength, high-plastic difficult-to-cut alloy, quasi-static tensile yield stress σ _s is more than 250 MPa, and elongation δ is less than 15%. and dynamic yield stress sigma _d is quasi-static tensile strength greater than the yield stress sigma _s low plasticity flame cutting alloys, quasi-static tensile yield stress sigma _s is 100MPa～250MPa, elongation δ is 40% to 15%, It is classified into three types of high-strength, high-plastic free-cutting alloys in which the dynamic yield stress σ _d is smaller than the quasi-static tensile yield stress σ _s. The method for producing a brass alloy having different zinc equivalents in step 1) is to use Cu, Zn, Si and Al elements as Cu: 56 to 66 wt. %, Zn: 33 to 42 wt. %, Si: 0.4 to 1.5 wt. %, Al: 0.2 to 1.5 wt. t% and B: 0.003 to 0.01 wt. %, Ti: 0.03 to 0.06 wt. The high strength and high strength according to claim 1, wherein the zinc equivalent X% in all the components of the brass alloy is 39 to 49%, and the microstructure is α + β phase. Quantitative identification method for lead-free silicon brass that has plasticity and free-cutting properties and is environmentally friendly. Design the phase composition by zinc equivalent regulation, formula

(Wherein, X%: zinc _{equivalents, C Zn:} alloying pure zinc _{content, C Cu:} alloying pure copper content, ΣC _i K _i: content of all alloy elements excluding Cu, and Zn in the alloy _{C i} quantitative friendly lead-free silicon brass environment has a high strength and high plasticity, free-cutting according to claim 2, characterized in that to calculate the zinc equivalent by the sum of the product of the zinc equivalent coefficient K _i) Identification method. In step 2), J. G. Using the test scheme developed by William, the cutting dynamic yield stress σ _d when cutting silicon brass alloys with different zinc equivalents was calculated, specifically,
Equation from the force balance of the sheared surface

(Here, σ _d : dynamic yield stress, h _c / sin φ: length of sheared surface, K _b : fracture toughness of material, w _c : cutting width corresponding to _{the relief amount ap} of the cutting edge in the cylindrical turning test. , F _c : main cutting force, F _t : feed resistance)
The slope of the straight line obtained by fitting the change relationship between F _c / w _c − (F _t / w _c ) tan φ and (h _c / 2) (tan φ + 1 / tan φ) with a straight line is defined as the cutting dynamic yield stress σ _d . The method for quantitatively identifying lead-free silicon brass, which has high strength, high plasticity, and free-cutting property and is environmentally friendly, according to claim 1, which comprises the above. The cutting test in step 2) is performed on a CNC lathe equipped with a cutting force measuring device, the cutting sample is a cylindrical rod, the cutting tool material is a commercially available WC-8Co tool, and the value of the feed rate f is changed as a machining parameter. The high strength, high plasticity, and free-cutting property according to claim 4, wherein the value of the feed rate f is set to 0.05 to 0.3 mm / r based on the usual cutting parameters of the brass alloy. Quantitative identification method for environment-friendly lead-free silicon brass. Force balance equation

(Here, h _c / sin φ: length of shear surface, h _c : thickness of cutting layer, φ: shear angle of silicon brass sample, K _b : fracture toughness of material, w _c : cutting width, F _c : main The cutting dynamic yield stress σ _d is determined from the cutting force ( _{Ft: feed resistance).}
The above force balance equation,

Convert to
Calculate the values of F _c / w _c − (F _t / w _c ) tan φ and (h _c / 2) (tan φ + 1 / tan φ).
The change relationship of F _c / w _c − (F _t / w _c ) tan φ and (h _c / 2) (tan φ + 1 / tan φ) is plotted and linearly fitted, and the slope is defined as the cutting dynamic yield stress σ _d .
The shear angle φ of the silicon brass sample is calculated by the formula.

(Here, γ ₀ : rake angle of cutting tool, Λ _h is

Quantitative value of environmentally friendly lead-free silicon brass having high strength, high plasticity, and free-cutting property according to claim 5, which is calculated according to a cutting deformation coefficient (h _{ch: average chip thickness) determined from} Identification method. The tip thickness of the sawtooth tip, h _ch, etc., is _{to simplify h ch} = H− (h _s / 2) (where H: the maximum height of the sawtooth tip, h _s : the height of the sawtooth). The method for quantitatively identifying lead-free silicon brass, which has high strength, high plasticity, and free-cutting property and is environmentally friendly, according to claim 6, which is obtained by. Quantitative amount of lead-free silicon brass which has high strength, high plasticity, free turning property and is environmentally friendly according to claim 6, wherein the thickness h _{c of the cutting layer is equal to the feed f value in the cylindrical turning test.} Identification method. The eco-friendly lead-free silicon brass having high strength, high plasticity, and free turning property according to claim 6, wherein the cutting width w _{c is equal to the relief amount ap} of the cutting edge in the cylindrical turning test. Quantitative identification method. The high strength according to claim 1, wherein in step 3), the high-strength, high-plastic free-cutting alloy is used for manufacturing bathroom equipment, household hardware, heat sinks, electronic devices, and low-temperature pipelines. A quantitative identification method for lead-free silicon brass that has strength, high plasticity, and free-cutting properties and is environmentally friendly.

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