洛氏硬度是以壓痕塑性變形深度來(lái)確定硬度值的指標(biāo)，以0.002毫米作為一個(gè)硬度單位。在洛氏硬度試驗(yàn)中采用不同的壓頭和不同的試驗(yàn)力，會(huì)產(chǎn)生不同的組合，對(duì)應(yīng)于洛氏硬度不同的標(biāo)尺。常用的有3個(gè)標(biāo)尺，其應(yīng)用涵蓋了幾乎所有常用的金屬材料。

洛氏硬度（HR）測(cè)試，當(dāng)被測(cè)樣品過(guò)小或者布氏硬度（HB）大于450時(shí)，就改用洛氏硬度計(jì)量。試驗(yàn)方法是用一個(gè)頂角為120度的金剛石圓錐體或直徑為1.5875mm/3.175mm/ 6.35mm/12.7mm的鋼球，在一定載荷下壓入被測(cè)材料表面，由壓痕深度求出材料的硬度。萊州市試驗(yàn)機(jī)金剛石工具廠是以機(jī)床主軸、回轉(zhuǎn)頂針、絲杠絲桿、軸加工、數(shù)控車床加工、刀柄刀桿、夾頭接桿為公司的主打產(chǎn)品，品質(zhì)保障，最常用的三種標(biāo)尺為A、B、C，即HRA、HRB、HRC，要根據(jù)實(shí)驗(yàn)材料硬度的不同，選用不同硬度范圍的標(biāo)尺來(lái)表示：

HRA是采用60Kg載荷和鉆石錐壓入器求得的硬度，用于硬度較高的材料。例如：鋼材薄板、硬質(zhì)合金。

HRB 是采用100Kg載荷和直徑1.5875mm淬硬的鋼球求得的硬度，用于硬度較低的材料。例如：軟鋼、有色金屬、退火鋼等。

HRC 是采用150Kg載荷和鉆石錐壓入器求得的硬度，用于硬度較高的材料。例如：淬火鋼、鑄鐵等。

硬度標(biāo)尺：

洛氏硬度試驗(yàn)采用三種試驗(yàn)力，三種壓頭，它們共有9種組合，對(duì)應(yīng)于洛氏硬度的9個(gè)標(biāo)尺：HRA、HRB、HRC、HRD、HRE、HRF、HRG、HRH和HRK。這9個(gè)標(biāo)尺的應(yīng)用涵蓋了幾乎所有常用的金屬材料。

HRA 60kg載荷金剛石錐壓入器；HRB 100kg載荷1/16"直徑鋼球壓頭；HRC 150kg載荷金剛石錐壓入器；最常用標(biāo)尺是HRC、HRB和HRF，其中HRC標(biāo)尺用于測(cè)試淬火鋼、回火鋼、調(diào)質(zhì)鋼和部分不銹鋼。這是金屬加工行業(yè)應(yīng)用最多的硬度試驗(yàn)方法。HRB標(biāo)尺用于測(cè)試各種退火鋼、正火鋼、軟鋼、部分不銹鋼及較硬的銅合金。HRF標(biāo)尺用于測(cè)試純銅、較軟的銅合金和硬鋁合金。HRA標(biāo)尺盡管也可用于大多數(shù)黑色金屬，但是實(shí)際應(yīng)用上一般只限于測(cè)試硬質(zhì)合金和薄硬鋼帶材料。

表面洛氏硬度試驗(yàn)采用三種試驗(yàn)力，兩種壓頭，它們有6種組合，對(duì)應(yīng)于表面洛氏硬度的6個(gè)標(biāo)尺。表面洛氏硬度試驗(yàn)是對(duì)洛氏硬度試驗(yàn)的一種補(bǔ)充，在采用洛氏硬度試驗(yàn)時(shí)，當(dāng)遇到材料較薄，試樣較小，表面硬化層較淺或測(cè)試表面鍍覆層時(shí)，就應(yīng)改用表面洛氏硬度試驗(yàn)。這時(shí)采用與洛氏硬度試驗(yàn)相同的壓頭，采用只有洛氏硬度試驗(yàn)幾分之一大小的試驗(yàn)力，就可以在上述試樣上得到有效的硬度試驗(yàn)結(jié)果。表面洛氏硬度的N標(biāo)尺適用于類似洛氏硬度的HRC、HRA和HRD測(cè)試的材料；T標(biāo)尺適用于類似洛氏硬度的HRB、HRF和HRG測(cè)試的材料。

洛氏硬度計(jì)和表面洛氏硬度計(jì)的標(biāo)尺（即不同的壓頭和試驗(yàn)力組合）通常按材料種類、試樣厚度和硬度范圍三方面的因素來(lái)選擇，具體選擇方法敘述如下：

1、按材料種類選擇

A標(biāo)尺多用于測(cè)量碳化鎢、硬質(zhì)合金、表面硬化零件等等的硬度；

B標(biāo)尺多用于測(cè)量有色金屬、合金及退火鋼等低硬度的零件的硬度；

C標(biāo)尺多用于測(cè)量碳鋼、工具鋼及合金鋼等經(jīng)淬火、回火處理的試樣的硬度。

按材料選擇并不是一種嚴(yán)格的做法。因?yàn)槊恳环N材料隨著其所采用的不同的熱處理工藝，其最終硬度不可能相同，因此所適應(yīng)的硬度標(biāo)尺也不會(huì)相同。

2、按樣品的硬度范圍選擇：

1）樣品硬度與材料成分及熱處理工藝的關(guān)系：在相同的熱處理工藝下，材料的含碳量越高，材料的硬度也越高。對(duì)應(yīng)于相同的材料，由工藝引起的硬度高低是：淬火、正火、退火。

2）各種洛氏硬度標(biāo)尺的適應(yīng)范圍。每種洛氏硬度標(biāo)尺都有一個(gè)可用范圍，這一點(diǎn)很容易從硬度計(jì)刻度盤上的分度來(lái)確定。

3、按厚度或硬化層深度

洛氏硬度試驗(yàn)對(duì)樣品試樣有要求，其厚度不能小于殘余壓痕深度的10倍，試樣背面不能出現(xiàn)明顯的變形痕跡。由此樣品的厚度決定了載荷的選擇，載荷必須保證其所引起的變形小于樣品的最小厚度。對(duì)于每一種硬度試驗(yàn)，都存在最小可測(cè)量厚度。

測(cè)試：

有一些標(biāo)尺（如含N、T、W、X、Y的標(biāo)尺）是對(duì)洛氏硬度試驗(yàn)的補(bǔ)充，由表面洛氏硬度試驗(yàn)得出。因?yàn)樵诓捎寐迨嫌捕仍囼?yàn)時(shí)，當(dāng)遇到材料較薄，試樣較小，表面硬化層較淺或測(cè)試表面鍍覆層等情況時(shí)，就應(yīng)改用表面洛氏硬度試驗(yàn)。

之所以分出這么多種標(biāo)尺，是因?yàn)樵跇?biāo)尺的使用中，越靠近上下限就越不準(zhǔn)。

HRC標(biāo)尺的使用范圍是20~70HRC，當(dāng)硬度值小于20HRC時(shí)，因?yàn)閴侯^的圓錐部分壓入太多，靈敏度下降，這時(shí)應(yīng)改用HRB標(biāo)尺。萊州市試驗(yàn)機(jī)金剛石工具廠是以機(jī)床主軸、回轉(zhuǎn)頂針、絲杠絲桿、軸加工、數(shù)控車床加工、刀柄刀桿、夾頭接桿為公司的主打產(chǎn)品，盡管HRC標(biāo)尺的上限值為70HRC，但是當(dāng)試樣硬度大于67HRC時(shí)，壓頭尖端承受的壓力過(guò)大，金剛石容易損壞，壓頭壽命會(huì)大大縮短，所以在測(cè)量偏HRC標(biāo)尺上限的硬度時(shí)，應(yīng)使用HRA標(biāo)尺，因?yàn)镠RA的上限范圍同HRC相當(dāng)，但試驗(yàn)力要小很多。

HRA標(biāo)尺的使用范圍是20-88HRA，由美國(guó)標(biāo)準(zhǔn)ASTM E140可以獲得以下?lián)Q算關(guān)系：27HRA≈30HRB；60HRA≈100HRB≈20HRC；85.6HRA≈68HRC；可見，在同等數(shù)值的情況下，對(duì)應(yīng)標(biāo)尺的硬度由高到低為C、A、B，但HRA標(biāo)尺的測(cè)試范圍廣，基本包含了HRB和HRC，涵蓋了從軟鋼（HRB）、硬鋼（HRC）到硬質(zhì)合金的硬度范圍。

但事實(shí)上，HRA標(biāo)尺很少用于測(cè)試軟鋼，主要用于測(cè)試薄硬鋼板、深層滲碳鋼和硬質(zhì)合金。在硬質(zhì)合金方面，由于技術(shù)進(jìn)步，有些材料硬度已達(dá)到93-94HRA，材料硬度超出HRA的測(cè)量范圍上限已成為慣例。依借于HRA標(biāo)尺測(cè)試范圍廣的特性，在使用洛氏硬度計(jì)測(cè)試鋼試樣時(shí)，如果不知試樣是軟鋼還是硬鋼，可先用HRA標(biāo)尺試測(cè)一下，當(dāng)硬度值小于60HRA時(shí)可改用HRB標(biāo)尺，當(dāng)硬度值大于60HRA時(shí)可改用HRC標(biāo)尺。

HRB標(biāo)尺的使用范圍是20~100HRB，當(dāng)硬度值低于20HRB時(shí)，由于鋼球的壓入深度過(guò)大，金屬蠕變加劇，試樣在試驗(yàn)力作用下的變形時(shí)間延長(zhǎng)，測(cè)試值準(zhǔn)確度降低，此時(shí)應(yīng)改用HRF標(biāo)尺。當(dāng)硬度值大于100HRB時(shí)，因?yàn)殇撉驂喝肷疃冗^(guò)淺，靈敏度降低，精度下降，此時(shí)應(yīng)改用HRC標(biāo)尺。

在使用HRB標(biāo)尺測(cè)試鋼試樣時(shí)，一個(gè)特別值得注意的地方是：當(dāng)預(yù)先不知道試樣是軟鋼還是硬鋼時(shí)，決不可使用HRB標(biāo)尺做測(cè)試，因?yàn)橛娩撉驂侯^誤測(cè)了淬火鋼，鋼球就可能會(huì)變形，鋼球壓頭就會(huì)損壞，這是鋼球壓頭損壞的主要原因。遇到這種情況時(shí)應(yīng)先用金剛石壓頭，用HRA標(biāo)尺測(cè)試一下，再?zèng)Q定是用HRB還是用HRC。

HRF標(biāo)尺的使用范圍是60~100HRF。HRF標(biāo)尺是國(guó)外使用較多的一個(gè)標(biāo)尺，它是測(cè)試純銅和較軟的銅合金材料很好的檢測(cè)手段。但是在中國(guó)，也存在標(biāo)準(zhǔn)硬度塊短缺的問(wèn)題，它的應(yīng)用也受到了限制。

HRG標(biāo)尺適用于HRB值接近100的材料，對(duì)于鈹青銅、磷青銅、可鍛鑄鐵這些硬度范圍介于HRB標(biāo)尺的高端和HRC標(biāo)尺低端的材料，如果改用HRG標(biāo)尺，就可以大大改善測(cè)試的靈敏度，提高測(cè)試精度。

萊州市試驗(yàn)機(jī)金剛石工具廠是以機(jī)床頂針、刀柄刀桿、軸加工、CNC數(shù)控加工、主軸絲杠、夾頭接桿、非標(biāo)件加工為公司的主打產(chǎn)品，品質(zhì)保障，值得信賴！

Rockwell hardness is an index of hardness value determined by the depth of indentation plastic deformation, with 0.002 mm as a hardness unit. Different head and different test force in rockwell hardness test will produce different combinations, corresponding to different scales of rockwell hardness. There are three scales commonly used, and their application covers almost all commonly used metal materials.

Rockwell hardness (HR) test, when the sample measured is too small or the brinell hardness (HB) is greater than 450, then rockwell hardness measurement is used. The test method is to use a diamond cone with a top Angle of 120 ° or a steel ball with a diameter of 1.5875mm/3.175mm/ 6.35mm/12.7mm to press into the surface of the measured material under a certain load and calculate the hardness of the material from the indentation depth. Laizhou city tester diamond tools factory is A machine tool spindle, rotary plunger, screw, screw, shaft processing, CNC lathe processing, the handle bar, chuck jaw for the company's flagship product, quality guarantee, the most commonly used three kinds of scale as A, B, C, namely, HRA, HRB, HRC, according to the different experimental material hardness, choose different hardness range of scale to indicate:

HRA is the hardness obtained by using 60Kg load and drill cone presser. It is used for materials with higher hardness. For example: steel sheet, hard alloy.

HRB is a hardness obtained from a hardened steel ball with a diameter of 1.5875mm and a load of 100Kg. Examples: mild steel, nonferrous metals, annealed steel, etc.

HRC is the hardness obtained by 150Kg load and drill cone presser. It is used for materials with higher hardness. For example: hardened steel, cast iron and so on.

Hardness scale:

Rockwell hardness test USES three test forces and three pressure heads. There are nine combinations corresponding to the nine scales of rockwell hardness: HRA, HRB, HRC, HRD, HRE, HRF, HRG, HRH and HRK. The application of these nine scales covers almost all commonly used metal materials.

HRA 60kg load diamond cone presser; HRB 100kg load 1/16" diameter steel ball head; HRC 150kg load diamond cone presser; The most commonly used gauges are HRC, HRB, and HRF. HRC gauges are used to test hardened, tempered, tempered, and partially stainless steels. This is the most widely used hardness test method in the metal processing industry. HRB gauge is used to test all kinds of annealed steel, normalizing steel, mild steel, some stainless steel and hard copper alloy. HRF gauge is used for testing pure copper, softer copper alloys and duralumin. Although HRA gauges can also be used for most ferrous metals, their practical applications are generally limited to testing hard and thin steel strip materials.

The surface rockwell hardness test USES three test forces, two pressure heads, and six combinations corresponding to six scales of surface rockwell hardness. The surface rockwell hardness test is a supplement to the rockwell hardness test. When the rockwell hardness test is used, when the material is thinner, the sample is smaller, the surface hardening layer is shallow or the test surface is coated, the rockwell hardness test should be used instead. A valid hardness test result can be obtained on the sample by using the same head as the rockwell hardness test and a test force that is only a fraction of the size of the rockwell hardness test. The N scale of surface rockwell hardness is applicable to materials tested with HRC, HRA and HRD similar to rockwell hardness. The T scale is suitable for testing materials with HRB, HRF and HRG hardness similar to rockwell hardness.

The scales of rockwell and surface rockwell durometers (i.e. different combination of head and test force) are usually selected according to the type of material, sample thickness and hardness range. The specific selection method is described as follows:

1. Choose according to material type

A scale is mainly used to measure the hardness of tungsten carbide, hard alloy, surface hardened parts and so on.

B scale is mainly used to measure the hardness of non-ferrous metals, alloys, annealed steel and other low-hardness parts.

C scale is mainly used to measure the hardness of carbon steel, tool steel and alloy steel after quenching and tempering.

Selecting by material is not a strict practice. Because each material with its different heat treatment process, its final hardness can not be the same, so adapt to the hardness scale will not be the same.

2. Choose according to the hardness range of the sample:

1) relationship between sample hardness and material composition and heat treatment process: under the same heat treatment process, the higher the carbon content of the material, the higher the hardness of the material. Corresponding to the same material, the hardness caused by the process is: quenching, normalizing, annealing.

2) applicable range of various rockwell hardness scales. Each rockwell hardness scale has a usable range that can be easily determined from the scale on the durometer dial.

3. According to thickness or depth of hardened layer

Rockwell hardness test requires that the thickness of the sample should not be less than 10 times of the residual indentation depth, and there should be no obvious deformation traces on the back side of the sample. The thickness of the sample determines the choice of load. The load must be less than the minimum thickness of the sample. For each hardness test, a minimum measurable thickness exists.

Testing:

Some scales (such as N, T, W, X, Y) complement the rockwell hardness test and are derived from the surface rockwell hardness test. Because in the use of rockwell hardness test, when the material is thinner, the sample is small, the surface hardening layer is shallow or the test surface coating layer, we should use the surface rockwell hardness test.

The reason why there are so many kinds of rulers is that in the use of rulers, the closer they are to the upper and lower limits, the less accurate they are.

The range of use of HRC ruler is 20~70HRC. When the hardness value is less than 20HRC, the sensitivity decreases because the cone part of the head is pressed too much, then HRB ruler should be used. Diamond tools factory laizhou city testing machine is the machine tool spindle, rotary plunger, screw, screw, shaft processing, CNC lathe processing, the handle bar, chuck jaw for the company's flagship product, although the HRC the upper limit of the scale of 70 HRC, but when the sample hardness greater than 67 HRC, head tip pressure is too large, diamond is easy to damage, head will shorten the service life, so in the measurement of partial HRC hardness scale limit, you should use HRA rod, because the limit range with HRC HRA was, but much smaller test force.

The scope of HRA ruler is 20-88hra, and the following conversion relationship can be obtained from American standard ASTM E140:27HRA≈30HRB; 60 hra material 100 HRB material 20 HRC; 85.6 68 HRC HRA material; It can be seen that, at the same value, the hardness of the corresponding ruler is C, A and B from high to low, but the HRA ruler has A wide test range, basically including HRB and HRC, covering the hardness range from mild steel (HRB) and hard steel (HRC) to hard alloy.

But in fact, the HRA gauge is rarely used to test mild steel. It is mainly used to test thin and hard steel plate, deep carburized carbon steel and hard alloy. In terms of cemented carbide, due to technological progress, the hardness of some materials has reached 93-94hra, and it has become a convention that the hardness of materials exceeds the upper limit of the measurement range of HRA. According to the characteristics of the wide range of HRA scale test, when using rockwell hardness tester to test steel samples, if you do not know whether the samples are soft steel or hard steel, you can use HRA scale to test first. When the hardness value is less than 60HRA, you can use HRB scale; when the hardness value is greater than 60HRA, you can use HRC scale.

The range of use of HRB scale is 20~100HRB. When the hardness value is lower than 20HRB, HRF scale should be used instead because the pressing depth of steel ball is too large, the creep of metal is intensified, the deformation time of sample under the action of test force is prolonged, and the accuracy of test value is decreased. When the hardness value is greater than 100HRB, the sensitivity and accuracy of the steel ball will be reduced due to the shallow pressing depth, so HRC scale should be used instead.

In the use of HRB test steel sample scale, a special note: when don't know in advance sample is soft or hard steel, steel must never use HRB test scale, because with a steel ball head misplaced the hardened steel, steel ball could be out of shape, ball head will be damaged, this is the main reason for the damage of steel ball head. In this case, diamond head should be used first, HRA ruler should be used to test it, and then HRB or HRC should be used.

The HRF ruler can be used from 60 to 100HRF. HRF ruler is one of the most widely used rulers in foreign countries. It is a good method to test pure copper and soft copper alloy materials. But in China, there is also a shortage of standard blocks, and its use is limited.

HRG ruler is suitable for materials with HRB value close to 100. Beryllium bronze, phosphorus bronze and malleable iron whose hardness range is between the high end of HRB ruler and the low end of HRC ruler can greatly improve the sensitivity and accuracy of the test if HRG ruler is used instead.

Laizhou testing machine diamond tool factory is a machine tool thimble, shank, shaft processing, CNC CNC processing, spindle screw, chuck rod, non-standard parts processing as the company's main products, quality assurance, trustworthy!