硬度換算表,計算器及試驗洛氏,布氏,維氏和更多

簡介:什麼是硬度

硬度是任何材料的特性,當它受到外力抵抗變形到其形狀。 硬度測試是技術和工程應用中很重要,因為它有助於確定硬度和材料的拉伸強度。

It helps to develop a clear understanding of whether the specimen being tested is suitable for specific applications. It helps industries to make safe and high-quality end products which meet the safety regulations and guidelines laid down by the relevant authorities.

The different types of hardness and various methods of hardness testing and determining the hardness values are discussed below:

划痕硬度

Scratch hardness is the ability of a material to resist deformation usually by scratches and abrasions. Scratch hardness is one type of hardness which is measured when a specimen surface is scratched by a stylus which is dragged along its surface under a fixed test load.

Scratch hardness method defines the resistance of a material to plowing by a hard stylus. It measures the hardness of the material and its ability to resist scratches and abrasions. Generally, a scratch hardness tester consists of a stylus, portable sample holding stage, load-applying device, and a data processing and display unit.

The earliest scratch hardness tests were conducted by Friedrich Mohs in 1820 who also developed the Mohs scale. The scratch hardness test measures the resistance of the specimen to fracture or permanent deformation due to friction caused by the stylus along its surface.

This test uses a harder material to scratch the specimen surface which is made of a relatively softer material. When you need to test coatings, then scratch hardness refers to the force which is necessary to cut through the film to the substrate. Mohs scale is used for measuring the scratch resistance of material along with a measuring device known as sclerometer.

壓痕硬度

Indentation hardness refers to the hardness of a material which is determined by making an indentation on its surface using an appropriate indenter under a test load.

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There are many different indentation testing methods which measure the depth of indentation made on the specimen surface for measuring its hardness. Indentation hardness tests can be further subdivided into two categories- macro indentation tests and micro-indentation tests. Macro indentation tests make use of large test loads in excess of 1Kgf and can go up to 3000Kgf in some cases.自動轉數顯小負荷維氏硬度計

The prominent type of macro indentation testing methods includes Rockwell hardness testing method, Brinell method, Vickers test, Knoop hardness testing method, etc. Micro-indentation testing, on the other hand, is used for measuring the hardness of soft metals, thin and small specimen, etc.

適用於微壓痕硬度測試的測試負載低得多,可以在1之間的範圍內,以1000gf。 微壓痕測試可以用於在微觀尺度上測量的硬度變化。 維氏方法和努氏硬度的測試方法是兩種流行的微壓痕硬度測試方法。

壓痕硬度測試可能容易出錯。 同時測量硬度誤差的主要來源包括技術差,檢測設備的校準不當,試樣表面的不當精加工等。測試表面需要不受任何污垢,氧化,或潤滑獲得硬度的可靠估計。 壓頭還應當垂直於試樣表面的任何傾斜將導致錯誤的硬度測量。

回彈硬度

Rebound hardness which is also known as dynamic hardness measures the hardness of a material by determining the height to which a diamond-tipped hammer bounces when it is dropped from a height on to the specimen. This type of hardness is related to elasticity.

Rebound hardness is generally measured using the Leeb rebound hardness test. This method was developed in 1975 by Leeb and Brandestini by using a portable hardness tester. This tester provided a new alternative to the usually intricate and complex traditional hardness testing equipment.自動轉編程的數字顯示維氏硬度計

The Leeb rebound hardness testing method follows standardized procedures. The velocity of the body ranges between 1.4 m/s to 3 m/s. Under this method, the velocity of the body before and after the impact is measured to determine the hardness of the specimen.

撞擊速度的回彈速度之比給出的試驗片的動態裡氏硬度。 用於製造對試樣的影響對象可以是碳化鎢鈷,陶瓷或金剛石,或具有不同半徑的球形壓頭。

由該方法確定的樣品的硬度表示為(例如)750 HL d,其中750表示硬度值,HL表示“根據裡氏硬度”和d表示裡氏方法碳化鎢 - 鈷的球形衝擊體的半徑在1.5mm和重量為4.5克。

選擇最佳的硬度測試方法

的材料的硬度取決於許多的類似的材料的均勻性,材料的類型,它的大小和條件的因素。

有不同類型的於需要為獲得最精確可靠的硬度測量仔細選擇硬度測試方法。

計算機硬度計(半自動)用於編程的運營商表
計算機硬度計(半自動)用於編程的運營商表

這就需要選擇理想的硬度測試方法包括 - 材料的類型進行測試之前,必須考慮的因素,該材料的硬度要被測試,該材料的均勻性,試樣的大小,如果安裝是必要的硬度測試,試樣的厚度等

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洛氏硬度試驗

洛氏硬度測試是測試硬度最常見的和快速的方法。 它通常是理想的拉爾尺寸樣品的測試硬度。

它可以在裝配線上或在實驗室中進行測試硬度使用。 它使用取決於材料的硬度要被測試的測量硬度的鋼球或鑽石末端錐形壓頭。

To start the Rockwell test, a minor load of generally 10Kgf is applied on the indenter. The indenter then moves under the test load on to the specimen surface. While the indenter is still under the influence of the minor test load, an additional major test load is also applied to it. This ensures better indentation on the specimen surface which is clear and measurable.

The Rockwell method of hardness testing is popular as it is not influenced by either the operator’s bias or the roughness of the surface whose hardness is being tested.

It does not make use of any sophisticated or costly optical equipment for measuring the hardness of specimen, which makes it a cost-effective method for hardness testing. It is a non-destructive method for hardness testing which means that the sample specimen being tested is not destroyed and it can be used for other purposes after the testing procedure is completed.洛氏硬度計(古典型)

This method has its drawbacks also as it is not very accurate compared to other methods of hardness testing. Small deviation in measuring the indentation depth can throw off the hardness readings considerably.

If the indenter in this method is worn out, then it can provide faulty hardness measurements which are non-reliable.

Rockwell hardness value is calculated using the conversion charts. There are nearly 30 Rockwell scales but most of the materials are covered by Rockwell C and B scales. The hardness values in Rockwell testing are represented as (example) 70 HRB where 60 is the hardness reading on the B scale.

 

布氏硬度試驗

The Brinell hardness test is one of the oldest and most widely used methods for hardness testing of materials. This method was developed by JA Brinell in the year 1900. It is ideal for measuring the hardness of specimens which are too rough or course to be measured by other methods.

The Brinell method involves usage of higher test loads which can go up to 3000Kgf and a ball indenter generally 10mm in diameter.電氣面洛氏硬度計

For measuring the hardness of softer metals and alloys, smaller test loads of up to 500Kgf are also used. The predetermined test load is applied to the spherical indenter which is held to the specimen surface for generally for 10-15 seconds and then moved.

The indentation depth made by the indenter on the specimen surface is then measured and studied using advanced optical equipment which ensures better accuracy and reliability.

The Brinell conversion chart is then used to convert the average diameter of the indentation made to the corresponding Brinell hardness value. Using the conversion charts, the Brinell hardness value can also be converted into the corresponding tensile strength.

The Brinell method of hardness testing comes with few drawbacks also. The operator can make mistakes in measuring the indentation depth on the specimen surface which can considerably impact the hardness measurements.

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Since the method involves advanced and sophisticated optical equipment for measuring the specimen hardness, it is costlier compared to the Rockwell method. It also takes more time to test hardness as the specimen surface needs to be prepared before testing.

The Brinell method will also not work accurately if the specimen surface is too thin i.e. less than 9.6 mm.

The hardness readings using the Brinell method are represented as 600 HBW where 600 denotes the hardness value and HBW denotes “Brinell Hardness” with tungsten ball indenter. If steel ball indenter is used then the readings will be represented as 600 HBS where HBS denotes “Brinell Hardness” with steel ball indenter.

維氏硬度試驗

The Vickers test uses the same principle as the Brinell method with the only exception being the type of indenter being used.

The type of indenter needs to be changed under the Brinell method depending on the type of material being tested. However, the same diamond indenter is used in the Vickers method for measuring the hardness of all specimen types.自動轉數顯小負荷維氏硬度計

The indenter used in this method is in the form of a right pyramid. A test load is applied on the indenter which presses itself against the specimen surface thereby leaving an indentation.

The diagonal lengths of these indentation marks are measured using optical systems, resulting in highly accurate hardness readings. The dwell time- the time for which the test force is applied through the indenter on the specimen surface- is generally between 10-15 seconds in this method.

The Vickers test using micro-test loads which are much lesser compared to the Brinell method. It is a microhardness testing method which is best suited for measuring the hardness of materials which are too thin or small for macro hardness testing.

這種方法最適合於測量的金屬薄片,小試樣等維氏試驗是其確保樣品可以使用的測試完成之後的非破壞性方法的硬度。 有維氏方法的一些限制。

它要求在試樣表面是從任何缺陷的分類,因此需要用於進行試驗之前,製備試樣表面的時間。 它至少需要30-60秒進行該測試,時間為獨占的採取製備試樣表面的時間。

不推薦用於在組裝線成批生產維氏試驗和更適合用於實驗室測試。 在維氏試驗的硬度測量被表示為700 HV / 10,其中700是已經在通過使用10公斤力試驗力被到達的維氏硬度值。

努氏硬度試驗

Knoop hardness testing method is an alternative to the Vickers method. It is a microhardness measuring method which is suitable for measuring the hardness of fragile and brittle materials like ceramics. It is also useful for hardness testing of small elongated areas like coatings.

The Knoop method also uses a pyramidal diamond as indenter, but the indenter is elongated instead of being a right pyramid as in the Vickers method. Since the method is used for hardness testing of fragile materials, it uses micro loads of up to 1Kgf.

The indenter used in this method penetrates the specimen surface only half as deep as in the Vickers method, which makes it perfect for hardness testing of the brittle specimen.

由於壓頭的形狀,努普方法更適合於測量像塗料更長拉長試樣。 值得注意的是,樣品表面應進行適當的測試努氏為了確保準確,可靠的硬度測量前要準備好是很重要的。

 

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