IN-SITU METALLOGRAPHY :
As an NDE technique, In-situ Metallography is ideal for assessing the remaining life of power and petrochemical plants. DRC Engineering Services, India has qualified and experienced field services team that regularly conducts In-situ Metallography on-site at major plants, refineries and process industries. This team from DRC determines in-service degradation of critical components of process plants operating under high temperature/ high pressure/ corrosive atmosphere. The technique enables real-time component condition monitoring and health assessments.
In-situ Metallography and replication is used for microstructural analysis when examining large components that cannot be easily moved or destructive sample preparation is difficult or not permissible. In-situ Metallography allows for quick on-site evaluation of a component’s metallurgical and heat treatment condition and assist investigators when carrying out a remaining life assessment study or a failure analysis project.

Scope
This procedure covers replica on weld metal, heat-affected zone and base metal.

Reference Standard: ASME

Surface Condition
The areas for replica shall be well polished.

Examination coverage
As per job requirement.

Equipment:
Polishing Grinder make Bose, Microscope make China and grits (60, 80, 120,240, 320, 400 & 600).

Couplant:
Diamond paste (5μ & 1μ), Alumina (Grade I, II & III) and Replica liquid (Acetone & Methanol acid).

Test Procedure:
A microscopic examination of each replica shall be made onsite to verify that it is of adequate quality and to note signs of material damage (e.g., creep micro- or macrocracking) which may require immediate attention.

Recording:
Result & structure shall be recorded in specified format.

Qualification:
Metallurgist.

IN- SITU REPLICATION as per (ASTM E 3, E 407)
OVERVIEW:
Replication is Non-Destructive Sampling Procedure records & preserves the topography of metallographic specimen as a negative relief on a plastic film. The microscopic replica can be examined using a light microscope (LM) on scanning electron microscope (SEM) for subsequent analysis. Specimens examined in SEM are vacuum coated with vaporized carbon or suitable metal to provide contrast & conductivity. The proper preparation of the test surface & of replica itself is of paramount importance & must receive careful attention.

PROCEDURE (Standard Operating Procedure)

DEMAGNETISE:- The work piece where In-situ replica is to be taken

COARSE GROUND THE SURFACE: - Use hand held grinder (AG5/AG4).

• Avoid excessive grinding.

FINE GROUND:- Use portable grinding machine.

• The surface in the following sequence of abrasive 80-120-220-320-500-800 -1000 grits.

POLISHING:- Using use & throw injector paste of

• The ground surface using velvet cloth: Metal power/Using lubricating fluid
• Diamond paste in the following (Metal power) Sequence 6μ, 3μ, 1μ:
• Lubrication/ thinning to be done:

CLEANING:- Use acetone with cotton puff.

• The polished surface.

ETCHING:- Use 20% Nital for carbon steel.

• The cleaned surface or low alloy steel

VIEW MICROSTRUCTURE: Using portable microscope

• Proceed to next step the 10X -objective Microstructure is visible & clear. 10X –eye piece
• Go back & starts from 1000 grit grinding till get a correct microstrure.

PLACEMENT OF REPLICA FILM:-

• Put 4 drops of ethyl acetate on one surface Use dropper of previously cut replica film & wipe with Fingure gently.
• Place wiped ethyl acetate surface of film on polished / etched surface & gently press to remove air gap.
• Paint black colour on other surface of replica Use permanent black marker pen film.
• Put double adhesive tape on the pasted replica.
• Place glass slide on the adhesive tape allow it to stick by gentle press.
• Remove glass slide slowly such replica also Comes out.
• Cover the replica with another glass slide wind with adhesive tape