In Situ Metallography

INDEX

1. INTRODUCTION

2. APPLICATION REQUIREMENTS

3. SAMPLE PREPARATION PROCESSES

4. RESULT

Field metallographic procedures are performed “on location” or in the “field” on components that are too large to bring to the metallographic laboratory. Generally, these components are still being used in service or must be returned to service and cannot be destructively sectioned or physically altered. Field metallography is also called in situ metallography, and it is sometimes called nondestructive metallography.

The major application areas are power plants, petroleum and natural gas pipelines, and welding quality inspection for metal constructions…etc.

In situ metallographic work must be performed on-site without damaging the components. This means that portable metallographic instruments for grinding, polishing, and etching procedures are required. Advantages - The technique is portable and can be used on-site. - In situ metallography can be used to monitor quality of purchased components. - Replication techniques are nondestructive. - Replicas are ideal for both flat and curved surfaces

- The techniques can be applied to a wide variety of materials.

Disadvantages

- Special portable equipment is required. - Contamination may be a problem in harsh or dusty environments. - The technique only analyzes the microstructure of the surface of a material/component.

A. GRINDING & POLISHING

B. REPLICA & ETCHING

C. PORTABLE MICROSCOPY

Order Code Description Equipment Used 90 01 MOBIPREP Portable grinding/polishing & Electrolytic etching

Equipment Accessories 90 11 Angle piece 90 °, with 3-mm collet on

90 14 Grinding and polishing carriers (5 pieces)

90 10 Etching-Pencil for electrolytic etching

Consumables 90 22 Paper Grinding Discs, 250 pieces (Ø 30 mm), 320 Grit

90 23 Paper Grinding Discs, 250 pieces ( Ø 30 mm), 500 Grit

90 24 Paper Grinding Discs, 250 pieces ( Ø 30 mm), 800 Grit

90 26 PORTO Polishing Cloth ( Ø 30 mm) for 0,25, 1, 3 microns (50 pcs.)

90 27 RADO Polishing Cloth (30 mm) for 6, 9 microns (50 pcs.)

39-331-M Diamond Paste, 6 Mic., 10gr. syringe

39-311-M Diamond Paste, 1 Mic., 10gr. syringe

Order Code Description Consumables 90 28 Cotton rolls (100 pcs) for electrolytic etching

90 40 Replica foil 35 microns thick, to be used with acetone

90 41 Microscope slide glasses

Order Code Description Equipment Used 90 02 MOBISCOPE - Portable Metallurgical Microscope

Equipment Accessories 90 30 Magnet Stage

66 10 IMAGIN Hardware set

GRINDING & POLISHING

Welded steel pipes will be investigated from the welding line.

First of all pipe sample grinded step by step with various grit grinding papers. Grinding papers are self

adhesive and can be removed from the grinding carriers easily. The mode switch is set to G (grinding)

in MOBIPREP.

After grinding operation polishing cloths (PORTO & RADO) are sticked on the carrier for polishing

operation.

Low speed value recommended for polishing and operation time tooks around 2-3 minutes according to

prepared surface area. The mode switch is set to P1 or P2.

ETCHING

Chemical etching made with 3% Nital solution and solution is applied for 10 sec – 1 min (depending on

the material). Then prepared surface is cleaned with ethanol and dried.

Also sample can be etched with electrolytic method by using optional Etching-Pencil.

MICROSCOPY

MOBISCOPE portable microscope provides up to 100x and 500x total magnification with 10x and 50x objectives which are supplied as standard. Optional 20x and 80x objectives are available. With the magnet stage, MOBISCOPE can be easily attached against the surface of any ferrous material at any angles on flat and curved surfaces. Also MOBISCOPE can be used with our IMAGIN hardware set by using special adapter which is supplied with microscope as standard.

To do so the anode (red wire) of the Etching- Pencil is to be connected to the sample or work piece by the clamp or the magnetic anode supplied. The Mod switch is set to E1 or E2. Removing the closing cap a cotton-wool tampon is inserted into the Etching-Pencil. Using the syringe filled with electrolyte and put into the filling hole on the side of the etching pencil the cotton-wool tampon is soaked with the relevant electrolyte. The pencil is wiped on the prepared spot until etching is done. Thus the etching result may be directly controlled and stopped using water.

After the metallographic preparation, the samples examined with MOBISCOPE Portable Metallurgical

Microscope (Order No: 90 12) with IMAGIN system. Microstructure of sample images can be seen below:

x100 x100