Gogortasuna Conversion Taula, kalkulagailua & Probak Rockwell, Brinell, Vickers eta gehiago

Sarrera: Zer da gogortasuna

Gogortasuna da edozein material jabetzakoak bere forma deformazioak aurre egiteko kanpoko indar bat jasaten. Gogortasuna probak aplikazioetan tekniko eta ingeniaritza garrantzitsua da gogortasuna eta material indarra trakzio zehazteko laguntzen baitu.

ale ari probatu aplikazio zehatzak egokia ote den ulertzeko argi bat garatzen laguntzen du. industriak segurtasun arauak eta ezarritako dagokien agintariek jarraibide betetzen dituzten segurua eta kalitatezkoa end produktuak egiteko laguntzen du.

gogortasuna eta gogortasuna probak hainbat metodo eta gogortasuna balioak zehazteko mota desberdinak aztertuko ditugu hemen:

Scratch gogortasuna

Scratch gogortasuna material baten gaitasuna Deformazio normalean aurre egiteko marratu eta abrasions da. Scratch gogortasuna gogortasuna mota bat den neurtzen denean ale azalera bat da hau da, bere azalera zehar arrastaka proba finkoa karga pean arkatz batek urratzen.

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.

koska gogortasuna

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.Automatikoa Torreta Digital Display kargatu Behe ​​Vickers gogortasuna Tester

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.

The test loads applied for micro-indentation hardness tests are much lower and can range between 1 to 1000gf. Micro-indentation tests can be used for measuring changes in hardness on a microscopic scale. Vickers method and Knoop hardness testing methods are two popular micro-indentation hardness testing methods.

Indentation hardness tests can be prone to errors. The main sources of errors while measuring hardness include poor technique, improper calibration of the testing equipment, improper finishing of the specimen surface, etc. The test surface needs to be free from any dirt, oxidation, or lubrication to get reliable estimates of hardness. The indenter should also be perpendicular to the specimen surface as any inclination will result in faulty hardness measurements.

errebotea gogortasuna

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.Display automatikoa Torreta programatutako Digital Vickers gogortasuna Tester

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.

The ratio of the impact velocity to the rebound velocity gives the dynamic Leeb hardness of the test specimen. The object used for making the impact on the specimen can be tungsten carbide cobalt, ceramic or diamond, or a ball-shaped indenter with different radius.

The sample hardness determined by this method is represented as (example) 750 HL D in which 750 denotes the hardness value, HL denotes “Hardness according to Leeb” and D represents Leeb method with spherical impact body of tungsten carbide-cobalt with a radius of 1.5 mm and weight of 4.5 grams.

Best gogortasuna probatzen metodoa hautatzea

The hardness of a material depends on a number of factors like homogeneity of the material, type of material, its size, and condition.

There are different types of methods for hardness testing which needs to be selected carefully for getting the most accurate and reliable hardness measurements.

Computer mikrogogortasuna Tester (Erdi-automatikoak) programatutako Carrier Table for
Computer mikrogogortasuna Tester (Erdi-automatikoak) programatutako Carrier Table for

Factors which need to be considered before selecting the ideal hardness testing methods include- the type of material to be tested, the hardness of the material to be tested, homogeneity of the material, size of the specimen, if mounting is necessary for hardness testing, thickness of the specimen, etc.

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Rockwell gogortasuna Test

Rockwell hardness testing is the most common and fast method for testing hardness. It is generally ideal for testing hardness of larges sized samples.

It can be used either on the assembly line or in laboratories for testing hardness. It uses a steel ball or diamond-tipped cone indenter for measuring hardness depending upon the hardness of the material to be tested.

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.Rockwell gogortasuna Tester (Mota Klasikoa)

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.

 

Brinell gogortasuna Test

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.Azalera Electric Rockwell gogortasuna Tester

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.

Brinell gogortasuna probak metodoa desabantaila batzuk ere egin dator. operadoreak akatsak egin ditzake ale azalera nabarmen eragin gogortasuna neurketa on koska sakonera neurtzeko.

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metodoa ekipamendu optiko aurreratuak eta sofistikatua dakar geroztik ale gogortasuna neurtzeko, costlier da aldean Rockwell metodoa da. ere denbora gehiago gogortasuna probatzeko ale azalera izango probak aurretik prestatu behar bezala hartzen du.

Brinell metodoa ere ez zehaztasunez lan ale azalera gehiegi mehe hau 9,6 mm baino txikiagoa bada.

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.

Vickers gogortasuna Test

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.Automatikoa Torreta Digital Display kargatu Behe ​​Vickers gogortasuna Tester

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.

This method is best suited for measuring the hardness of thin sheets of metals, small specimens, etc. The Vickers test is a non-destructive method which ensures that the specimen can be used after the testing is complete. There are a few limitations of the Vickers method.

It requires the specimen surface to be free from any imperfections and thus time is needed for preparing the specimen surface before conducting the test. It takes at least 30-60 seconds for conducting this test and the time is exclusive of the time taken for preparation of the specimen surface.

Vickers testing is not recommended for bulk production in assembly lines and is more suited for laboratory testing. The hardness measurements in the Vickers test are represented as 700 HV/10 where 700 is the Vickers hardness value which has been arrived at by using a 10Kgf test force.

Knoop gogortasuna Test

Knoop gogortasuna probak metodoa Vickers metodoa alternatiba bat da. a mikrogogortasuna neurtzeko metodoa hau da, zeramika bezalako materialak hauskorrak eta hauskorra gogortasuna neurtzeko egokia da. halaber gogortasuna estaldurak bezalako eremu txiki luzatua probak erabilgarria da.

Knoop metodoa ere piramide diamantea Indenter gisa erabiltzen du, baina Indenter ordez eskuin piramide Vickers metodoa bezala izatearen luze. Geroztik metodoa gogortasuna material hauskor probak egiteko erabiltzen da, mikro 1Kgf gehienez zamak erabiltzen du.

Metodo honetan erabilitako Indenter The ale azalera sartzen erdia bezain sakona Vickers metodoa, eta horrek ezin hobea da gogortasuna hauskorra ale probak bezala.

Dela Indenter forma, Knoop metodoa estaldurak bezala jada luze ale neurtzeko hobeto egokitzen da. Garrantzitsua da ale azalera prest egon behar du behar bezala Knoop zehatza eta fidagarria gogortasuna neurketa bermatzeko proba realización aurretik, kontuan izan.

 

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