This Presentation covers the basic concepts of Murex Hot-Cracking Test & Root-Pass Cracking Test. For more information, please refer the books mentioned in the references slide.... Thank you

1. Seminar On
Murex Hot-Cracking Test
&
Root-Pass Cracking Test
Melwin D’mello
M.E (Welding Engineering)
Centre for Materials Joining & Research (CEMAJOR),
Department of Manufacturing Engineering,
ANNAMALAI UNIVERSITY
Presented by

2. Weldability is defined as 'the capacity of a
material or a combination of materials to be welded
under fabrication conditions into a specific, suitably
designed structure, and to perform satisfactorily in
the intended service'.
Metallurgical compatibility
Mechanical soundness
Good serviceability
WELDABILITY

3. • Weldability depends on the process, operating parameters,
procedures, degree of restraint and the most important
factor is base metal chemical composition.
• Composition can determine inherent weldability, with some
alloys being inherently weldable.
• Others being inherently difficult to weld, and still others
being essentially unweldable.
• For those few materials (or assemblies) that are unweldable,
an alternative method of joining must be sought.

4. Cracks may occur in the weld metal or in the
HAZ. Sometimes they originate in one zone and
spread into the other.
These cracks are grouped into two categories, viz.,
(i)Hot Cracks.
(ii) Cold Cracks.
Classification of Weld Cracks

5. • Hot cracks occur mainly in the weld bead but
sometimes they may develop in the HAZ.
• When located in the weld metal they are referred to as
Solidification Cracks while in HAZ they are called
Liquation Cracks.
• Solidification cracks occur in the weld metal when the
metal is very hot.
Hot Cracks

6. Hot Cracks

7. Cold crack
• Cold cracking or HIC or delayed cracking, is the most
serious of all weld cracking problems particularly in the
welding of high strength steels.
• HIC occurs when the following four factors are present
simultaneously.
• Hydrogen in the weld metal
• High stresses
• Susceptible microstructure
• Relatively low temperature

8. Cold crack

9. Schematic of the Murex hot-crack test.
Murex Hot-Cracking Test

10. • The test is used for obtaining comparative
information on similar (or different) welding fillers.
• The test is performed by depositing a fillet weld in a
V-groove formed between two 0.5-in.-thick plates.
• Five seconds after welding has started, one of the
plates is rotated about the point of the vee by a
predetermined amount (1o/ sec.), usually 30”.
• The speed of rotation is adjusted to control straining
of the weld metal.
• Performance is measured based on lengths of
cracks appearing as a result of straining.
10

11. Specimen geometry of U-groove weld cracking test
Root-Pass Crack Test
11

12. This test was
specifically designed to
evaluate susceptibility
to cracking in the root
pass of multipass SMA
welding of thick
sections.
Schematic of the root-pass
crack-susceptibility test.
Root-Pass Crack Test.
12

13. A similar, related test, called the submerged-
arc-weld crack test, was developed for
evaluating the same thing for root passes made
by SAW.
After deposition of the first pass of weld metal,
slag removal, and cooling to 100°F (39”C), the
specimen is examined visually, by dye
penetrant, or by x-radiography. Performance is
based on the extent of weld-metal cracking.
13

14. REFERENCES
• Text Book : “Welding Process and Technology” by Dr. R.S
Parmar, 2015 edition.
• Text Book : “Welding Engineering and Technology” by Dr. R.S
Parmar, 2015 edition

15. Thank you