Metallographic Specimen Preparation

Select your material for specimen preparation process

Disclaimer: Specimen preparation techniques are for guidance purposes only. Kemet recommend these should be tested on non-critical samples first and offer free trials to help establish the optimum process using Kemet equipment and consumables.

Material: Gray Cast Iron

Results: The graphite flakes are uniformly distributed in the pearlitic matrix (A type graphite). Overetching should be avoided in order to prevent graphite pull-outs. The below given preparation method gives perfect results.

Etching: 2% Nital

Cutting: General Purpose 8A80NBK Aluminium Oxide cut-off wheel. TRENO-H Aluminium Oxide cut off wheels can also be used.

Mounting: Ecopress 100 Automatic Mounting Press with Black Phenolic Resin

Mechanical Preparation: FORCIPOL 1V Grinding / Polishing Machine + FORCIMAT Automatic Specimen Mover.

Parameter / Stage Surface Abrasive Lubricant Force per Sample, (N) Time min. Disc Speed, rpm Relative Rotation
Planar Grinding Met Disc Paper 180 Grit SiC Water 25 2 min. or until plane 300 Contra
Bramet Disc Paper
Fine Grinding. Met Disc Paper 400 Grit SiC Water 25 2 300 Contra
Bramet Disc Paper
Fine Grinding. Met Disc Paper 800 Grit SiC Water 25 2 300 Contra
Bramet Disc Paper
Fine Grinding. Met Disc Paper 1200 Grit SiC Water 20 2 250 Contra
Bramet Disc Paper
Final Polishing MRE Polishing Pad Alpha Alumina. 1µ Powder Water 15 4 150 Comp.

Magnification: 550X (Brightfield)

specimen preparation for Gray Cast Iron

Material: Historical China (ceramic)

Results: The microstructure of an Iznik (Nicea) china from 15th century. In polished surface, the coated and pointed zone are clearly seen. The dispersion of benthonid bonded quarsit grains is homogeneous. Low cutting force with low feed is recommended.

Cutting: MICRACUT 201 Precision Cut-off machine with ø200mm Kemet Diamond cut-off wheels

Mounting: Cold Mounting and Embedding Form

Mechanical Preparation: FORCIPOL 2V Grinding / Polishing Machine +FORCIMAT Automatic Specimen Mover.

Parameter / Stage Surface Abrasive Lubricant Force per Sample, (N) Time min. Disc Speed, rpm Relative Rotation
Planar Grinding Met Disc Paper 180 Grit SiC Water 30 2 min. or until plane 300 Contra
Bramet Disc Paper
Fine Grinding. Met Disc Paper 400 Grit SiC Water 30 2 300 Contra
Bramet Disc Paper
Met Disc Paper 600 Grit SiC Water 25 2 300 Contra
Bramet Disc Paper
Met Disc Paper 800 Grit SiC Water 25 2 300 Contra
Bramet Disc Paper
Met Disc Paper 1200 Grit SiC Water 20 2 250 Contra
Bramet Disc Paper
Final Polishing PSU-M Polishing Pad 0.25µ WP Diamond Suspension GW2 15 4 150 Contra

specimen preparation for ceramic

Material: 50 CrV4 Low alloy steel

Results: The existence of alloy carbides is due ro 1.1% chromium. Very thin carbide particles can be seen in the tempered martensitic matrix in the microstructure. Below given preparation method gives very good scratchfree surface.

Etching: 3% Nital

Cutting: General Purpose 8A80MBK Aluminium Oxide cut-off wheel. TRENO-M cut off wheels can also be used.

Mounting: Ecopress 100 Automatic Mounting Press with Hard Epoxy resin

Mechanical Preparation: FORCIPOL 2V Grinding / Polishing Machine + FORCIMAT Automatic Specimen Mover.

Parameter / Stage Surface Abrasive Lubricant Force per Sample, (N) Time min. Disc Speed, rpm Relative Rotation
Planar Grinding Met Disc Paper 180 Grit SiC Water 30 2 min. or until plane 300 Contra
Bramet Disc Paper
Fine Grinding. Met Disc Paper 400 Grit SiC Water 30 2 300 Contra
Bramet Disc Paper
Fine Grinding. Met Disc Paper 800 Grit SiC Water 30 2 300 Contra
Bramet Disc Paper
Pre Polishing NMH Polishing Pad 6µ WP Diamond Suspension Blue 25 3 200 Contra
Final Polishing MBL Polishing Pad 1µ WP Diamond Suspension Blue 20 4 150 Contra

Magnification: 300X

specimen preparation for 50 CrV4 Low alloy steel

Material: Mg-9Al (Magnesium Alloy)

Results: In this cast structure, the segregation can easily be seen. Eutectic area (dark) are located in grain boundaries.

Etching: 40ml ethanol + 10ml HNO3

Cutting: General purpose BC80NBK Silicon Carbide cut-off wheel. TRENO-NF cut off wheels can also be used.

Mounting: Ecopress 100 Automatic Mounting Press with Black Phenolic Powder.

Mechanical Preparation: Digiprep 251 Fully automated grinding and polishing system.

Parameter / Stage Surface Abrasive Lubricant Force per Sample, (N) Time min. Disc Speed, rpm Relative Rotation
Planar Grinding Diamond Grinding Disc 220 Grit Water 25 Until Plain 250 Contra
Grinding Diamond Grinding Disc 600 Grit Water 25 2 250 Contra
Fine Grinding Diamond Grinding Disc 1200 Grit Water 25 1 300 Contra
Pre Polishing Fine Grinding disc Green 3µ WP Diamond Suspension Blue 15 4 150 Contra
Final Polishing CHEM-H Polishing Pad COL-K (NC) Blue 20 2 150 Contra

Magnification: 90X (Brightfield)

specimen preparation for Mg-9Al (Magnesium Alloy)

Material: Nodular Cast Iron, Ferritic + Pearlitic

Results: This type of cast iron has more toughness. Ferrite zones (violet) and perlite surround the nodular graphites. Polarized light illumination is recommended to analyze the graphites.

Etching: 2% Nital

Cutting: General Purpose 8A80NBk Aluminium Oxide cut-off wheel. TRENO-H Aluminium Oxide cut off wheels can also be used.

Mounting: Ecopress 100 Automatic Mounting Press with Black Phenolic Hot Mounting resin

Mechanical Preparation: Digiprep 251 Fully automated grinding and polishing system.

Parameter / Stage Surface Abrasive Lubricant Force per Sample, (N) Time min. Disc Speed, rpm Relative Rotation
Planar Grinding Diamond Grinding Disc 220 Grit Water 25 Until Plain 250 Contra
Grinding Diamond Grinding Disc 600 Grit Water 25 2 250 Contra
Fine Grinding Diamond Grinding Disc 1200 Grit Water 25 1 300 Contra
Pre Polishing. Fine Grinding disc Green 3µ WM Diamond Suspension Blue 15 4 150 Contra
Final Polishing MBLPolishing Pad 1µ WM Liquid Diamond Blue 15 1 150 Contra

Magnification: 400X (Polarized Iight)

specimen preparation for Nodular Cast Iron, Ferritic + Pearlitic

Material: Nodular Cast Iron, Pearlitic

Results: Nodular Cast Iron is a commonly used engineering material. Strength and ductility is very good combined. Matrix is completely pearlitic and ferrite surrounds the graphite nodules.

Etching: 2% Nital

Cutting: General Purpose 8A80NBK Aluminium Oxide cut-off wheel. TRENO-H Aluminium Oxide cut off wheels can also be used.

Mounting: Ecopress 100 Automatic Mounting Press with Black Phenolic Hot mounting resin

Mechanical Preparation: Digiprep 251 Fully automated grinding and polishing system.

Parameter / Stage Surface Abrasive Lubricant Force per Sample, (N) Time min. Disc Speed, rpm Relative Rotation
Planar Grinding Diamond Grinding Disc 220 Grit Water 25 1 250 Contra
Grinding Diamond Grinding Disc 600 Grit Water 25 2 250 Contra
Fine Grinding Diamond Grinding Disc 1200 Grit Water 25 1 300 Contra
Pre Polishing. Fine Grinding disc Green 3µ WM Diamond Suspension Blue 15 4 150 Contra
Final Polishing MBL Polishing Pad 1µ WM Liquid Diamond Blue 15 1 150 Contra

Magnification: 200X (Polarized light)

specimen preparation for Nodular Cast Iron, Pearlitic

Material: Steel, Pearlitic

Results: Pearlitic steels are usually quenched and tempered. Microstructure is completely pearlitic. In high magnifications pearlitic constituents are observed.

Etching: 3% Nital

Cutting: General Purpose 8A80MBK Aluminium Oxide cut-off wheel. TRENO-M cut off wheels can also be used.

Mounting: Ecopress 100 Automatic Mounting Press with Epoxy, Hard

Mechanical Preparation: Digiprep 301 Fully automated grinding and polishing system.

Parameter / Stage Surface Abrasive Lubricant Force per Sample, (N) Time min. Disc Speed, rpm Relative Rotation
Planar Grinding Diamond Grinding Disc 220 Grit Water 25 1 250 Contra
Grinding Diamond Grinding Disc 600 Grit Water 25 2 250 Contra
Fine Grinding Diamond Grinding Disc 1200 Grit Water 25 1 300 Contra
Pre Polishing Fine Grinding disc Green 3µ WP Diamond Suspension Blue 15 4 150 Contra
Final Polishing MBL Polishing Pad 1µ WP Diamond Suspension Blue 15 1 150 Contra

Magnification: 1600X

specimen preparation for Steel, Pearlitic

Material: Commercial Pure Copper

Results: Since it is a soft material, it is recommended to use short times during mechanical preparation. By using polarized light, the oxide inclusions are easily visible. Twins are typical in annealed microstructure.

Etching: 50ml H2O + 50ml ammonia + 1-2 drops H2O2

Cutting: General purpose BC80NBK Silicon Carbide cut-off wheel. TRENO-NF cut off wheels can also be used.

Mounting: Ecopress 100 Automatic Mounting Press with Black Phenolic Hot Mounting Resin

Mechanical Preparation: FORCIPOL 300-1V Grinding / Polishing Machine + FORCIMAT Automatic Specimen Mover.

Parameter / Stage Surface Abrasive Lubricant Force per Sample, (N) Time min. Disc Speed, rpm Relative Rotation
Planar Grinding Met Disc Paper 180 Grit SiC Water 30 2 min. or until plane 300 Contra
Bramet Disc Paper
Fine Grinding. Met Disc Paper 400 Grit SiC Water 25 2 300 Contra
Bramet Disc Paper
Fine Grinding. Met Disc Paper 800 Grit SiC Water 25 2 300 Contra
Bramet Disc Paper
Fine Grinding. Met Disc Paper 1200 Grit SiC Water 25 2 300 Contra
Bramet Disc Paper
Pre Polishing. MBL Polishing Pad 1µ WP Diamond Suspension Blue 15 4 150 Comp.
Final Polishing CHEM-H Polishing Pad COL-K NC Water 15 2 150 Comp.

Magnification: 180X (Brightfield)

specimen preparation for Commercial Pure Copper

Material: Commercial Pure Titanium

Results: Microstructure consists of grains having equal axis. Since the material is soft, low sample forces should be applied during mechanical preparations.

Etching: Kroll solution (10 ml HF + 30 ml HNO3 + 50 ml H2O)

Cutting: General purpose GC80JBK Silicon Carbide cut-off wheel. TRENO-NF cut off wheels can also be used.

Mounting: Ecopress 100 Automatic Mounting Press with Black Phenolic Powder.

Mechanical Preparation: Digiprep 251 Fully automated grinding and polishing system.

Parameter / Stage Surface Abrasive Lubricant Force per Sample, (N) Time min. Disc Speed, rpm Relative Rotation
Planar Grinding Diamond Grinding Disc 220 Grit Water 25 Until Plain 250 Contra
Grinding Diamond Grinding Disc 600 Grit Water 25 2 250 Contra
Fine Grinding Diamond Grinding Disc 1200 Grit Water 25 1 300 Contra
Pre Polishing Fine Grinding disc Green 6µ WP Diamond Suspension Blue 15 4 150 Contra
Final Polishing CHEM-H COL-K NC Water 20 2 150 Contra

Alternative Process

Cutting: TRENO-NF Silicon Carbide cut-off wheel. GC80JBK cut off wheels can also be used.

Mounting: Ecopress 100 Automatic Mounting Press with Black Phenolic Powder.

Mechanical Preparation: Digiprep 301 Fully automated grinding and polishing system.

Parameter / Stage Surface Abrasive Lubricant Force per Sample, (N) Time min. Disc Speed, rpm Relative Rotation
Planar Grinding Diamond Grinding Disc 220 Grit Water 20 Until Plain 100 Contra
Pre Polishing MST 9µ WP Diamond Suspension Blue 25 4 300 Contra
Final Polishing CHEM-H COL-K NC Water 20 4 150 Contra

or

Parameter / Stage Surface Abrasive Lubricant Force per Sample, (N) Time min. Disc Speed, rpm Relative Rotation
Planar Grinding Bramet N 320 Grit Water 25 4 250 Comp
Pre Polishing MST 9µ WP Diamond Suspension Blue 40 5.5 250 Contra
Final Polishing CHEM-H COL-K NC Water 40 5 250 Contra

Magnification: 270X (Brightfield)

specimen preparation for Commercial Pure Titanium

Material: Rubber Joint

Results: The rubber joint is moulded for precise measuring. The details of the cross-section can be examined in details.

Cutting: Kemet Diamond Cut off wheel can also be used.

Mounting: Cold Mounting and Embedding Form

Mechanical Preparation: FORCIPOL 2V Grinding / Polishing Machine + FORCIMAT Automatic Specimen Mover.

Parameter / Stage Surface Abrasive Lubricant Force per Sample, (N) Time min. Disc Speed, rpm Relative Rotation
Planar Grinding Met Disc Paper 180 Grit Sic Water 20 2 min. or until plane 300 Contra
Bramet Disc Paper
Fine Grinding. Met Disc Paper 400 Grit Sic Water 25 2 250 Contra
Bramet Disc Paper
Met Disc Paper 800 Grit Sic Water 25 2 250 Contra
Bramet Disc Paper
Final Polishing ASF/MSF Polishing Pad 6μ WM Liquid Diamond GW2 20 3 150 Contra

specimen preparation for rubber joint

Material: Steel, case hardenable

Results: Equilibrium phases of carburizing region are seen obviously from surface towards inner areas. Carburizing region is thicker than 2 mm. Below given perparation method gives ideal results.

Etching: 2% Nital

Cutting: General purpose 8A80KBK Aluminium Oxide cut-off wheel TRENO-S Aluminium Oxide cut off wheels can also be used.

Mounting: Ecopress 100 Automatic Mounting Press with Epoxy, Hard, or Black Phenolic resin.

Mechanical Preparation: FORCIPOL 1V Grinding / Polishing Machine + FORCIMAT Automatic Specimen Mover.

Parameter / Stage Surface Abrasive Lubricant Force per Sample, (N) Time min. Disc Speed, rpm Relative Rotation
Planar Grinding Met Disc Paper 180 Grit SiC Water 30 2 min. oruntil plane 300 Contra
Bramet Disc Paper
Fine Grinding. Met Disc Paper 400 Grit SiC Water 30 2 300 Contra
Bramet Disc Paper
Fine Grinding. Met Disc Paper 800 Grit SiC Water 30 2 300 Contra
Bramet Disc Paper
Pre Polishing NMH Polishing Pad 6µ WP Diamond Suspension Blue 25 3 200 Contra
Final Polishing MBL Polishing Pad 1µ WP Diamond Suspension Blue 20 3 150 Contra

Magnification: 25X (Brightfield)

specimen preparation for Steel, case hardenable

Material: TiC Coating

Results: Single layer titanium carbide coating deposited on pearlitic low alloy steel through a thermochemical process. The thickness is approx. 10 microns and hardness is arround 2500 kg/mm². Careful low feed cutting recommended. Edge effects should be avoided.

Etching: 3% Nital

Cutting: General purpose 8A80KBK Aluminium Oxide cut-off wheel. TRENO-M cut off wheels can also be used.

Mounting: Ecopress 100 Automatic Mounting Press with Black Epoxy resin

Mechanical Preparation: Digiprep 300 Fully automated grinding and polishing system.

Parameter / Stage Surface Abrasive Lubricant Force per Sample, (N) Time min. Disc Speed, rpm Relative Rotation
Planar Grinding Diamond Grinding Disc 220 Grit Water 25 Until Plain 250 Contra
Grinding Diamond Grinding Disc 600 Grit Water 25 2 250 Contra
Fine Grinding Diamond Grinding Disc 1200 Grit Water 25 1 300 Contra
Pre Polishing Fine Grinding disc Green 6µ WP Diamond Suspension Blue 15 4 150 Contra
Final Polishing NMH Polishing Pad 1µ WP Diamond Suspension Blue 15 1 150 Contra

Magnification: 875X

specimen preparation for TiC Coating

Material: WC-Co Powder Metal

Results: Regularly shaped WC particles can easily be seen in the microstructure of this cermet sample containing %80 - 97 WC (+TiC) and Co. Diamond grinding pads can also be used for grinding process. After etching, potasium permanganate solution helps to obtain attractive images.

Etching: Murakami

Cutting: SERVOCUT A-250 Cut-off machine with ø250 Diamond cut-off wheels (600049)

Mounting: Ecopress 100 Automatic Mounting Press with Black Epoxy

Mechanical Preparation: Digiprep 251 Fully automated grinding and polishing system.

Parameter / Stage Surface Abrasive Lubricant Force per Sample, (N) Time min. Disc Speed, rpm Relative Rotation
Planar Grinding Diaflex (N) 200 Grit Water 25 1 250 Contra
Fine Grinding Diamond grinding disc 1200 Grit Water 25 2 300 Contra
Pre Polishing Fine grinding disc. Green 3µ WP Diamond Suspension Blue 15 4 150 Contra
Final Polishing MBL Polishing Pad 1µ WP Diamond Suspension Blue 15 1 150 Contra

Magnification: 800X

specimen preparation for WC-Co Powder Metal

Material: White Cast Iron, alloyed

Results: The microstructure of high chromium white cast iron consists of alloy carbides (dark colour) and ledeburite. Hardness is around 600 kg/mm² and has high wear resistance. To prevent edge effects, epoxy type mounting material is recommended.

Etching: Vilella

Cutting: General Purpose 8A80NBK Aluminium Oxide cut-off wheel. TRENO-H Aluminium Oxide cut off wheels can also be used.

Mounting: Ecopress 100 Automatic Mounting Press with Black-Epoxy (600811)

Mechanical Preparation: Digiprep 251 Fully automated grinding and polishing system.

Parameter / Stage Surface Abrasive Lubricant Force per Sample, (N) Time min. Disc Speed, rpm Relative Rotation
Planar Grinding Diamond Grinding Disc 220 Grit Water 25 Until Plain 250 Contra
Grinding Diamond Grinding Disc 600 Grit Water 25 2 250 Contra
Fine Grinding Diamond Grinding Disc 1200 Grit Water 25 2 300 Contra
Fine Grinding Fine Grinding disc Green 3µ WP Diamond Suspension Blue 15 4 150 Contra
Final Polishing NLH 1µ WP Diamond Suspension Blue 15 1 150 Contra
 

Magnification: 100X

specimen preparation for White Cast Iron, alloyed

Material: Carbon Fibre

Results: This process has produced a scratch free polish on all the various carbon fibre samples.

Cutting: Sections approx 5mm x 20mm were cut from each type of carbon fibre using a Micracut 201. Cut off wheel used - 200mm high concentration diamond, with a wheel speed of 600rpm and Feed rate: 100µ/s.

Mounting: Cold Mounting - 25mm Teflon Moulds, Kemet KEP Epoxy resin. Cure time is 8 hours at 20° C.

Mechanical Preparation: Digiprep 251 Fully automated grinding and polishing system. 300mm Aluminium LOD.

Parameter / Stage Surface Suspension Lubricant Platen Speed Head Speed Pressure Time
Planar Grinding 300mm 600G SiC Bramet N/A Water 150 CCW 80 25N 120 sec
Grinding 300mm 800G SiC Bramet N/A Water 150 CCW 80 25N 120 sec
Fine Grinding 300mm 1200G SiC Bramet N/A Water 150 CCW 100 25N 120 sec
Fine Grinding 300mm 2500G SiC Bramet N/A Water 150 CCW 100 25N 120 sec
Final Polishing 300mm ASFL-M Bramet 1µ WP Diamond Suspension GW2 150 CCW 80 25N 120 sec
 

specimen preparation for Carbon Fibre