Lamellar tearing is commonly observed in fusion welding and occurs near the heat-affected zone in flange plates of T-butt joints. It is due to segregation caused by excessive dilution from filler metal or improper heat input. Dilution and heat input must be controlled to minimize lamellar tearing.
Porosity appears as dark round or elongated indications in radiographs and is caused by gas inclusions from inadequate shielding or moisture contamination. It represents voids in the weld metal.
Lack of penetration occurs when weld metal fails to fully penetrate the joint, leaving a linear discontinuity. In radiographs it appears as a dark line along the weld centerline.
- Lamellar tearing is commonly observed discontinuity in fusion welding that occurs near the heat-affected zone in flange plates of T-butt joints. It is caused by factors like dilution and heat input during welding.
- Dilution is affected by the melted parent metal, melted filler metal, and weld width to depth ratio. Too low or too high heat input can both be detrimental.
- Solidification cracks can form due to the bead factor, which is the ratio of weld width to depth. A ratio greater than 1 or less than 1 can both result in cracks.
This document discusses various types of discontinuities that can occur in welds and base metals. It defines discontinuities as irregularities that interrupt an otherwise uniform structure, and defines defects as discontinuities that impair suitability for intended use. Various discontinuities are described such as cracks, incomplete fusion, porosity, undercut, and laminations. Cracks are generally the most detrimental as they can propagate under stress. The shape, location, and causes of different discontinuities are explained to help identify and evaluate their severity. The document provides detailed information on discontinuities to aid in non-destructive testing and quality control of welds.
This document discusses various types of welding discontinuities and defects that can occur during the welding process. It divides discontinuities into six main groups: cracks, cavities, solid inclusions, lack of fusion and penetration, imperfect shape, and miscellaneous defects. Within each group it provides examples and descriptions of specific defect types like porosity, slag inclusions, undercut, burn through, and more. It also discusses potential causes of defects and recommended remedies.
The document discusses various types of discontinuities and defects that can occur in welding, including cracks, porosity, inclusions, insufficient penetration, and more. It defines discontinuities as interruptions in material structure that are not necessarily defects, while defects render a part unable to meet standards. Causes, preventions, and potential repairs are provided for each issue. Engineering problems can arise from design mistakes, while weld process issues relate to techniques and metallurgy.
This document discusses welding defects and their causes. It outlines the four zones in a welded joint and how they appear on an iron-carbon phase diagram. The zones are the fusion zone, weld interface zone, heat affected zone, and base metal. Solidification can be epitaxial or non-epitaxial depending on whether filler metal is used. Common welding defects include cracks, porosity, inclusions, incomplete fusion, imperfect shape, and residual stresses. Various defect types like longitudinal cracks and underbead cracks are described in more detail.
This document discusses design guidelines and best practices for producing zinc diecastings for electroplating. It provides rules for minimum radii, recessed features, hole sizes and spacing to improve platability. It also covers factors that influence quality like alloy composition, melting practices, and die design. Defects that can occur like cold shuts, blisters, die soldering, shrinkage and laking are described along with techniques to prevent them.
The document provides information about manual metal arc welding (SMAW) process. It discusses the history of welding, capabilities and limitations of SMAW, types of electrodes and their compositions, welding techniques, joint preparation, common elements in welding processes, safety equipment and practices, recommended cable sizes, and causes and remedies of common welding defects.
The document discusses common weld defects that can occur in thermal power plants, including porosity, slag inclusions, excess penetration, incomplete fusion, undercut, inadequate joint penetration, cracking, and welding debris. It describes the causes and effects of each defect and measures to prevent their occurrence in order to ensure weld quality and structural integrity.
- Lamellar tearing is commonly observed discontinuity in fusion welding that occurs near the heat-affected zone in flange plates of T-butt joints. It is caused by factors like dilution and heat input during welding.
- Dilution is affected by the melted parent metal, melted filler metal, and weld width to depth ratio. Too low or too high heat input can both be detrimental.
- Solidification cracks can form due to the bead factor, which is the ratio of weld width to depth. A ratio greater than 1 or less than 1 can both result in cracks.
This document discusses various types of discontinuities that can occur in welds and base metals. It defines discontinuities as irregularities that interrupt an otherwise uniform structure, and defines defects as discontinuities that impair suitability for intended use. Various discontinuities are described such as cracks, incomplete fusion, porosity, undercut, and laminations. Cracks are generally the most detrimental as they can propagate under stress. The shape, location, and causes of different discontinuities are explained to help identify and evaluate their severity. The document provides detailed information on discontinuities to aid in non-destructive testing and quality control of welds.
This document discusses various types of welding discontinuities and defects that can occur during the welding process. It divides discontinuities into six main groups: cracks, cavities, solid inclusions, lack of fusion and penetration, imperfect shape, and miscellaneous defects. Within each group it provides examples and descriptions of specific defect types like porosity, slag inclusions, undercut, burn through, and more. It also discusses potential causes of defects and recommended remedies.
The document discusses various types of discontinuities and defects that can occur in welding, including cracks, porosity, inclusions, insufficient penetration, and more. It defines discontinuities as interruptions in material structure that are not necessarily defects, while defects render a part unable to meet standards. Causes, preventions, and potential repairs are provided for each issue. Engineering problems can arise from design mistakes, while weld process issues relate to techniques and metallurgy.
This document discusses welding defects and their causes. It outlines the four zones in a welded joint and how they appear on an iron-carbon phase diagram. The zones are the fusion zone, weld interface zone, heat affected zone, and base metal. Solidification can be epitaxial or non-epitaxial depending on whether filler metal is used. Common welding defects include cracks, porosity, inclusions, incomplete fusion, imperfect shape, and residual stresses. Various defect types like longitudinal cracks and underbead cracks are described in more detail.
This document discusses design guidelines and best practices for producing zinc diecastings for electroplating. It provides rules for minimum radii, recessed features, hole sizes and spacing to improve platability. It also covers factors that influence quality like alloy composition, melting practices, and die design. Defects that can occur like cold shuts, blisters, die soldering, shrinkage and laking are described along with techniques to prevent them.
The document provides information about manual metal arc welding (SMAW) process. It discusses the history of welding, capabilities and limitations of SMAW, types of electrodes and their compositions, welding techniques, joint preparation, common elements in welding processes, safety equipment and practices, recommended cable sizes, and causes and remedies of common welding defects.
The document discusses common weld defects that can occur in thermal power plants, including porosity, slag inclusions, excess penetration, incomplete fusion, undercut, inadequate joint penetration, cracking, and welding debris. It describes the causes and effects of each defect and measures to prevent their occurrence in order to ensure weld quality and structural integrity.
Intergranular corrosion occurs along grain boundaries and preferentially attacks the boundaries rather than the grain interiors. It is caused by compositional differences at grain boundaries that create galvanic cells. Sensitization can occur during heating when chromium carbides precipitate out at grain boundaries, leaving the adjacent metal depleted in chromium and more susceptible to corrosion. Two types of intergranular corrosion that can occur during welding are knife line attack, which affects a narrow band of metal near the weld fusion line, and weld decay, which develops farther from the weld in non-stabilized steels. Prevention methods include using stabilized grades of stainless steel and performing post-weld heat treatments.
The document summarizes corrosion of weldments. It discusses the microstructure of weldments and the distinct regions that form. It then covers the various forms of weld corrosion including galvanic, pitting, crevice, intergranular, stress corrosion, and hydrogen cracking. Factors that influence weld corrosion like material selection and welding parameters are presented. Testing methods for weld corrosion like linear polarization resistance and corrosion potential measurements are briefly described.
This document discusses soldering and welding techniques for joining metals. It describes soldering as joining metals with a lower-melting alloy called solder. Key requirements for good solder include having a melting point below the base metals and similar strength. Hard solders like gold and silver solders are used in dentistry. Welding joins metals without another alloy, using techniques like spot welding, arc welding, and laser welding. Spot welding passes a current through the metals to generate heat and join them, while maintaining pressure until cooled. Fluxes are also discussed which help remove oxides during the process. Proper cleaning, temperature control, pressure, and techniques are needed for successful soldering and welding.
There are numerous welding processes including arc welding, electron beam welding,
friction welding, laser welding, and resistance welding. This article will concentrate on arc
welding, which is the most common technique used to join most steels. Factors affecting
weld quality will be discussed and how to avoid common weld defects will be presented.
Arc welding requires striking a low-voltage, high-current arc between an electrode and the
base metal. The intense heat generated with this arc melts the base metal and allows the
joining of two components. The characteristic of the metal that is being welded and the joint
type (i.e. groove, fillet, etc.) dictates the welding parameters and the procedure that needs to
be followed to obtain a sound weld joint.
Corrosion is the deterioration of metals through chemical reactions with the environment. There are several types of corrosion, including galvanic corrosion which occurs when two dissimilar metals are in electrical contact in an electrolyte, leading the less noble metal to corrode faster. Pitting corrosion causes localized holes or pits in the metal surface. Selective leaching corrosion removes specific elements from alloys, like removing zinc from brass. Proper material selection, coatings, inhibitors, and cathodic protection can prevent various corrosion types.
The document discusses various common weld discontinuities and defects such as gas pores, slag inclusions, incomplete penetration, lack of fusion, cracks, and undercut. It describes the causes of these defects which can include trapped gas during solidification, contaminated base metal, improper welding parameters, and faulty joint preparation. Remedies suggested to avoid defects are ensuring adequate shielding from wind, using clean electrodes, maintaining the proper arc length, travel speed, and current level.
Welding Defects
Eurotech Now inteducing Welding Defects. Welding Defect is any type of flaw in the object which requires welding. Seven type of Welding Defect
Seven type of Common weld defects include:
1. Lack of fusion
2. Lack of penetration or excess penetration
3. Porosity
4. Inclusions
5. Cracking
6. Undercut
7. Lamellar tearing
Any of these defects are potentially disastrous as they can all give rise to high stress intensities which may result in sudden unexpected failure below the design load or in the case of cyclic loading, failure after fewer load cycles than predicted.
This document discusses metals used in orthopaedics, including their properties, applications, advantages, and disadvantages. It describes common metals like stainless steel, cobalt alloys, and titanium alloys. Stainless steel is inexpensive but has corrosion over time. Cobalt alloys are biocompatible with high strength but expensive. Titanium alloys have excellent biocompatibility properties but lower strength. The document also covers corrosion, metal failure modes, and considerations for metal removal and mixing implants.
1) Amino formic acid can form in low pressure zones and corrode stainless steel (SS) by destroying the passive film.
2) Field inspections found SS corrosion at heat affected zones, ferrite rich regions, welds, and in urea reactor linings and condenser tube supports.
3) Laboratory tests confirmed the possibility of amino formic acid formation from ammonia and carbon dioxide, and that oxygen and the quality of passive films influence corrosion rates, with weaker films on delta ferrite regions corroding at higher rates.
Soldering and Brazing are an integral part of dentistry, especially in prosthodontics and crown and bridge procedure. it is also used in implant-supported prosthetics.
Soldering and welding are the integral part of dentistry specially in prosthodontics and crown and bridge procedure. it is also used in implant supported prosthetic.
The document discusses the design of welded joints. It begins by defining a welded joint as a permanent fusion of two parts achieved through heating and optionally applying pressure and a filler material. Welding provides advantages over riveted joints like lighter weight and greater efficiency. Various welding processes are described including gas, electric arc, thermit and forge welding. Common welded joint types like lap, butt, corner and T-joints are also outlined. The document then examines the strength calculations for transverse and parallel fillet welds as well as butt joints. It concludes by discussing stresses in eccentrically loaded and unsymmetrical welded sections.
The document discusses various welding defects including lamellar tearing, porosity, underfill, insufficient
penetration, wagon tracks, arc strikes, and incomplete fusion. Lamellar tearing occurs beneath welds in rolled steel
plate and is caused by transverse strain from welding, a weld orientation parallel to inclusions, and poor material
ductility. Porosity is caused by absorbed gases like nitrogen, oxygen, and hydrogen which become trapped during
solidification. Prevention methods for defects include using proper joint design, welding techniques, materials, and
preheating when necessary. Defects require removal and rewelding to repair.
This document discusses various topics related to welding metallurgy including:
- The classification of commercial welding processes such as gas welding, arc welding, and high density beam welding.
- How the microstructure of metals changes during the welding process as the weld metal transitions from liquid to solid states.
- Factors that influence the heat input required for welding like material thickness, thermal conductivity, and preheating temperature.
- Different welding parameters like current, voltage, speed, and electrode diameter and how they affect the weld bead.
- Common weld defects such as lack of penetration, porosity, cracks and how to prevent them.
- How residual stresses are induced during welding
This document provides an overview of welding, including definitions, types of welding processes, factors that affect weldability, classifications of joints and welds, and descriptions of common welding techniques such as gas welding, arc welding, forge welding, and submerged arc welding. It discusses the equipment, steps, advantages, and disadvantages of various welding methods.
Soldering is a process that joins two metal parts by applying heat and using a filler metal that melts at a lower temperature than the base metals. The filler metal, usually an alloy of tin and lead, provides stability and conductivity when it cools and solidifies. There are two main types of soldering - hard soldering uses silver or zinc alloys for joints that require high strength, while soft soldering uses tin-lead alloys for electrical and electronics work where flexibility is important. Basic equipment for soldering includes an electrically heated soldering iron, soldering wire, flux to prepare the surfaces and aid bonding, and a stand and sponge to manage the iron tip.
Fusion welding uses heat to melt materials that are then joined together as they solidify. Common fusion welding methods include arc, resistance, oxyfuel, and laser welding. Solid-state welding joins materials without melting using pressure and sometimes heat. Welding allows the production of parts that would be difficult or impossible to form as a single piece through other manufacturing methods. Inspection methods are used to evaluate welds and identify defects.
The document discusses various types of welded joints, including lap joints, butt joints, and fillet welds. It describes the advantages of welded joints over riveted joints. Various welding processes are covered, including fusion welding processes like gas welding and electric arc welding. The document provides formulas to calculate the strength of different welded joint configurations, like transverse and parallel fillet welds, and discusses special cases like circular fillet welds subjected to torsion or bending moments. Design considerations for different welded joints are also presented.
Intergranular corrosion occurs along grain boundaries and preferentially attacks the boundaries rather than the grain interiors. It is caused by compositional differences at grain boundaries that create galvanic cells. Sensitization can occur during heating when chromium carbides precipitate out at grain boundaries, leaving the adjacent metal depleted in chromium and more susceptible to corrosion. Two types of intergranular corrosion that can occur during welding are knife line attack, which affects a narrow band of metal near the weld fusion line, and weld decay, which develops farther from the weld in non-stabilized steels. Prevention methods include using stabilized grades of stainless steel and performing post-weld heat treatments.
The document summarizes corrosion of weldments. It discusses the microstructure of weldments and the distinct regions that form. It then covers the various forms of weld corrosion including galvanic, pitting, crevice, intergranular, stress corrosion, and hydrogen cracking. Factors that influence weld corrosion like material selection and welding parameters are presented. Testing methods for weld corrosion like linear polarization resistance and corrosion potential measurements are briefly described.
This document discusses soldering and welding techniques for joining metals. It describes soldering as joining metals with a lower-melting alloy called solder. Key requirements for good solder include having a melting point below the base metals and similar strength. Hard solders like gold and silver solders are used in dentistry. Welding joins metals without another alloy, using techniques like spot welding, arc welding, and laser welding. Spot welding passes a current through the metals to generate heat and join them, while maintaining pressure until cooled. Fluxes are also discussed which help remove oxides during the process. Proper cleaning, temperature control, pressure, and techniques are needed for successful soldering and welding.
There are numerous welding processes including arc welding, electron beam welding,
friction welding, laser welding, and resistance welding. This article will concentrate on arc
welding, which is the most common technique used to join most steels. Factors affecting
weld quality will be discussed and how to avoid common weld defects will be presented.
Arc welding requires striking a low-voltage, high-current arc between an electrode and the
base metal. The intense heat generated with this arc melts the base metal and allows the
joining of two components. The characteristic of the metal that is being welded and the joint
type (i.e. groove, fillet, etc.) dictates the welding parameters and the procedure that needs to
be followed to obtain a sound weld joint.
Corrosion is the deterioration of metals through chemical reactions with the environment. There are several types of corrosion, including galvanic corrosion which occurs when two dissimilar metals are in electrical contact in an electrolyte, leading the less noble metal to corrode faster. Pitting corrosion causes localized holes or pits in the metal surface. Selective leaching corrosion removes specific elements from alloys, like removing zinc from brass. Proper material selection, coatings, inhibitors, and cathodic protection can prevent various corrosion types.
The document discusses various common weld discontinuities and defects such as gas pores, slag inclusions, incomplete penetration, lack of fusion, cracks, and undercut. It describes the causes of these defects which can include trapped gas during solidification, contaminated base metal, improper welding parameters, and faulty joint preparation. Remedies suggested to avoid defects are ensuring adequate shielding from wind, using clean electrodes, maintaining the proper arc length, travel speed, and current level.
Welding Defects
Eurotech Now inteducing Welding Defects. Welding Defect is any type of flaw in the object which requires welding. Seven type of Welding Defect
Seven type of Common weld defects include:
1. Lack of fusion
2. Lack of penetration or excess penetration
3. Porosity
4. Inclusions
5. Cracking
6. Undercut
7. Lamellar tearing
Any of these defects are potentially disastrous as they can all give rise to high stress intensities which may result in sudden unexpected failure below the design load or in the case of cyclic loading, failure after fewer load cycles than predicted.
This document discusses metals used in orthopaedics, including their properties, applications, advantages, and disadvantages. It describes common metals like stainless steel, cobalt alloys, and titanium alloys. Stainless steel is inexpensive but has corrosion over time. Cobalt alloys are biocompatible with high strength but expensive. Titanium alloys have excellent biocompatibility properties but lower strength. The document also covers corrosion, metal failure modes, and considerations for metal removal and mixing implants.
1) Amino formic acid can form in low pressure zones and corrode stainless steel (SS) by destroying the passive film.
2) Field inspections found SS corrosion at heat affected zones, ferrite rich regions, welds, and in urea reactor linings and condenser tube supports.
3) Laboratory tests confirmed the possibility of amino formic acid formation from ammonia and carbon dioxide, and that oxygen and the quality of passive films influence corrosion rates, with weaker films on delta ferrite regions corroding at higher rates.
Soldering and Brazing are an integral part of dentistry, especially in prosthodontics and crown and bridge procedure. it is also used in implant-supported prosthetics.
Soldering and welding are the integral part of dentistry specially in prosthodontics and crown and bridge procedure. it is also used in implant supported prosthetic.
The document discusses the design of welded joints. It begins by defining a welded joint as a permanent fusion of two parts achieved through heating and optionally applying pressure and a filler material. Welding provides advantages over riveted joints like lighter weight and greater efficiency. Various welding processes are described including gas, electric arc, thermit and forge welding. Common welded joint types like lap, butt, corner and T-joints are also outlined. The document then examines the strength calculations for transverse and parallel fillet welds as well as butt joints. It concludes by discussing stresses in eccentrically loaded and unsymmetrical welded sections.
The document discusses various welding defects including lamellar tearing, porosity, underfill, insufficient
penetration, wagon tracks, arc strikes, and incomplete fusion. Lamellar tearing occurs beneath welds in rolled steel
plate and is caused by transverse strain from welding, a weld orientation parallel to inclusions, and poor material
ductility. Porosity is caused by absorbed gases like nitrogen, oxygen, and hydrogen which become trapped during
solidification. Prevention methods for defects include using proper joint design, welding techniques, materials, and
preheating when necessary. Defects require removal and rewelding to repair.
This document discusses various topics related to welding metallurgy including:
- The classification of commercial welding processes such as gas welding, arc welding, and high density beam welding.
- How the microstructure of metals changes during the welding process as the weld metal transitions from liquid to solid states.
- Factors that influence the heat input required for welding like material thickness, thermal conductivity, and preheating temperature.
- Different welding parameters like current, voltage, speed, and electrode diameter and how they affect the weld bead.
- Common weld defects such as lack of penetration, porosity, cracks and how to prevent them.
- How residual stresses are induced during welding
This document provides an overview of welding, including definitions, types of welding processes, factors that affect weldability, classifications of joints and welds, and descriptions of common welding techniques such as gas welding, arc welding, forge welding, and submerged arc welding. It discusses the equipment, steps, advantages, and disadvantages of various welding methods.
Soldering is a process that joins two metal parts by applying heat and using a filler metal that melts at a lower temperature than the base metals. The filler metal, usually an alloy of tin and lead, provides stability and conductivity when it cools and solidifies. There are two main types of soldering - hard soldering uses silver or zinc alloys for joints that require high strength, while soft soldering uses tin-lead alloys for electrical and electronics work where flexibility is important. Basic equipment for soldering includes an electrically heated soldering iron, soldering wire, flux to prepare the surfaces and aid bonding, and a stand and sponge to manage the iron tip.
Fusion welding uses heat to melt materials that are then joined together as they solidify. Common fusion welding methods include arc, resistance, oxyfuel, and laser welding. Solid-state welding joins materials without melting using pressure and sometimes heat. Welding allows the production of parts that would be difficult or impossible to form as a single piece through other manufacturing methods. Inspection methods are used to evaluate welds and identify defects.
The document discusses various types of welded joints, including lap joints, butt joints, and fillet welds. It describes the advantages of welded joints over riveted joints. Various welding processes are covered, including fusion welding processes like gas welding and electric arc welding. The document provides formulas to calculate the strength of different welded joint configurations, like transverse and parallel fillet welds, and discusses special cases like circular fillet welds subjected to torsion or bending moments. Design considerations for different welded joints are also presented.
Optimizing Gradle Builds - Gradle DPE Tour Berlin 2024Sinan KOZAK
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Embedded machine learning-based road conditions and driving behavior monitoringIJECEIAES
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4. COMMONLY OBSERVED DISCONTINUITIES
IN FUSION WELDING
TYPE EXISTS REMARKS
Lamination Pm Base metal, genarally near mid thickness of section.
Delamination Pm ,,
Seams & laps Pm Base metal surface, often at all times longitudinal.
Lamellar tears Pm Invariably near the HAZ in flange plate of T-butt joint.
Cracks Pm, Wm
Wm/Pm
Restraint, Hot, Brittle & Under bead cold cracks; which may be
either in longitudinal or transvers direction.
Crater cracks Wm Usually with multi axial cracks at the point of termination.
Fissures Wm Micro cracks generally in fully austenitic stainless steel & less
ductile metal.
Stray flash Pm Appears away from the weld seam as a trail of arc spots with
micro fissures, excesively brittle & hard character.
Spatters Pm Globular weld particles ejected out of an arc zone & scattered
shabbily around over the base metal.
Pm = Parent metal; Wm = Weld metal; Pm/Wm = Junction of weld & base metal
Continued...
5. Weld decay &
stress corros-
ion cracks
Pm Precipitation of chromium carbide in austenitic stainless steels &
severely degrading the corrosion resistance property in HAZ; which
may also be associated with the stress corrosion cracks.
Oxidation Wm Inadequacy in gas shield or gas purge from the root side causes a
heavy black scale or an extremely rough crinkled appearance.
Craters Wm An unfilled concave crater causes a point of stress raiser.
Underfill Wm Inadequate weld metal filling and causing weakness.
Undercut Wm/Pm Groove made by the arc force & left unfilled, causes severe stress
concentration.
Overlap Wm/Pm Accumulation of weld, without fusion, causes an extremely voilent
point of sstress raiser.
Lack of fusion Wm,
Wm/Pm
Lack of union between the two weld beads or weld & base metal
causes stress concentration.
Lack of
penetration
Pm Inadequacy of through thickness fusion depth.
Solid particle
inclusion
Wm Trapped slag particle, tungsten or oxide (Al2O3) in weld.
Gas inclusion Wm Gas voids contained within the weld causes: Blow hole, Gas pore,
Piping, Worm holes, Linear, Clustered or Scattered porasity.
Pm = Parent metal; Wm = Weld metal; Pm/Wm = Junction of weld & base metal
11. The dilution:
Fm
Pm
Wm
Wm = Fm + Pm
Dilution% = Pm / Wm X 100
Pm = Melted Parent metal
Fm = Melted Filler metal
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½ãìŒã , ÔÌãããä¦ã †‡ãŠ
Øãì¶ã ¦ããè¶ã ý •ãõÔããè
ÔãâØããä¦ã ºãõã䟾ããñ ,
¦ãõÔããñ Öãè ¹ãŠË ªãè¶ã ýý
12. The heat input:
Kj / mm = I.V./ S.1000
I = Current across the arc.
V = Voltage across the arc.
S = The rate of arc motion mm/Sec.
‘‘Too low or high heat input both may equally be
proved detrimental.’’
‚ããä¦ã ÔãÌãèã
Ìããä•ãæã::
13.
14. Solidification cracks due to the bead factor:
W = Bead Width
P = Bead Depth
W
P P
W
W/P>1 W/P<1
That is W/P
15.
16.
17.
18. Cracks is detected in a radiograph, only when it produces a
change in thickness that is parallel to the x-ray beam. It appears
often zig-jagged with faint irregular line. Cracks can also appear
sometime as "tail" to an inclusion or porosity.
19.
20.
21.
22.
23.
24.
25.
26. Carbon equivalent Recommended procedure
Lesser than 0.40% Any electrode may be used, no problem up to the
combined thickness of 50mm.
Greater than 0.40% Preheat 100 to 200 0C or switch over to the basic
electrode.
Up to 0.55% Preheat 200 to 350 0C or switch over to the basic
electrode with reduced temp.
Abov 0.55% Use only the basic electrode & also preheat 200 -
350 0C or switch over to stainless steel electrode
of high ferrite.
C eq% = C% +
Mn%
6
(Cr + Mo + V)%
5 15
(Cu+Ni)%
+ +
27. Preheat Temp. for C & C-Mn Steel only:
0F = 1,000 (C% - 0.11) + 18 t"
Where C% is only up to 0.65% max.
A Saiferian formula for preheat to prevent cold cracks;
0C = 350 [C]e - 0.25
[C]e= [C]c + [C]t
[C]c = C% + + +
(Mn + Cr)%
9
Ni%
18
7Mo%
90
[C]t = [C]c X 0.005 t
t = Thickness in mm
28.
29.
30.
31.
32.
33.
34. Undercut is an erosion of the base metal next to the toe of the weld
face. It appears in radiograph as a dark irregular line on outer edge
of the weld.
35. Root undercut is an erosion of the base metal next to the root of the
weld. It appears in radiographic images as a dark irregular line offset
from the centerline of the weldment. Undercutting is not as straight
edged as LOP because it does not follow the straight edge
36. Root concavity or suck back is a condition where the weld metal
has contracted as it cools down & has been drawn up into the root of
the weld. On a film it appears similar to the lack of root penetration
but the line has irregular wide edges and placed in the middle.
37.
38.
39. Cold lap is a condition where the weld metal does not fuse with the
base metal or the previous weld bead (interpass cold lap). The arc
does not melt the base metal and causes the molten puddle to flow
into the base metl without the proper bonding.
40. Incomplete fusion is a condition where the weld metal does not
fuse with the base metal. Appearance on radiograph is usually a
darker line or lines oriented in the direction of the weld seam along
the weld joining area.
41.
42. Burn through (icicles) results when too much heat causes weld to
pierce through. Lumps of weld metal sag through the seam creating
a thick globular condition on the root face. On a radiograph, burn
through appears as dark spots surrounded by light globular areas.
Whiskers are the short lengths of electrode wire, visible on
the top or bottom surfaces of the weld or contained within the
weld. On radiograph they appear as light, "wire like" indications.
43.
44. Lack of penetration occurs when the weld metal fails to penetrate
through the joint. Allows a linear stress riser like discontinuity from
which a crack may initiate. The appearance on a radiograph is a dark
well-defined straight edges that follows the land or root face down the
center of a joint.
45.
46. •Gas pore _ singular.
•Blowhole _ singular.
•Scattered Porasity.
•Cluster Porasity.
•Linear Porasity.
•Piping.
• Worm holes.
Gas inclusion
Fine Severe
47.
48.
49.
50.
51.
52. Porosity appears often as dark round irregular spots in clusters or
rows. Sometimes it is elongated and may have an appearance of a
tail. This is the result of gas attempting to escape while the metal is
still in a liquid state & is called wormhole porosity. All porosity is
indeed a void will have a darker density than the surrounding.
53. Cluster porosity is caused when electrodes are contaminated with
moisture or hydrocarbon. It appears like regular porosity in a film
but the indications will be grouped close together.
57. Slag inclusions are the nonmetallic solid materials trapped in weld
or between the weld and base metal. In a radiograph, dark, jagged
asymmetrical shapes within the weld or along the weld joint areas
are indicative of slag inclusions.
58.
59. Tungsten inclusions. Tungsten is a brittle and dense material used
as an electrode in tungsten inert gas welding. If an incorrect welding
procedures & skill is performed, then only the tungsten gets trapped.
Radiographically, tungsten is more dense than aluminum or steel;
therefore, it shows as a lighter area with a distinct outline on the
radiograph
60. Oxide inclusions are usually visible on the surface of a weld mtal
(especially aluminum). Oxide inclusions are less dense than the surr -
ounding metals and, thus it appears as dark irregular shaped discon
-tinuity in radiograph. This is also referred as puckering in ISO.
61.
62.
63. The radiographic image is a noticeable difference in density between
the two mismatched pieces. The difference in density is caused by the
difference in material thickness. The dark, straight line is caused by
failure of the weld metal to fuse with the land area.
64.
65.
66.
67. Excessive reinforcement is an area of a weld added in excess of
that specified by the drawings and codes. The appearance on a rad-
iograph is a localized & less darker area. A visual examination will
easily determine if the weld reinforcement is in excess.
68.
69.
70.
71.
72. Underfilling is an area where the deposited weld metal is less than
the required thickness. It is easy to determine by RT films, because
the image density in the area of inadequacy will be darker than the
surrounding image density.
73. Distortion
:
Distortion is an unavoidable phenom
-enon of fusion welding.
Type:
• Longitudinal distortion; &
• Transvers distortion.
• Angular distortion;
76. Remedy: only to minimise.
• Reduce the cause of shrinkage forces;
• Make use of the shrinkage forces; &
• Balance the shrinkage forces.
77. Reduce the cause of shrinkage forces:
1. Do not weld __ if possible.
2. Reduce the number of joints.
3. Improve the joint design & fit-up.
4. Avoid excessive root gap & mismatch.
5. Avoid over welding.
6. Reduce the number of runs.
7. Use larger size electrodes.
8. Use iron powder type electrode.
9. Use semi or fully mechanized welding.
79. t
W
W
Effective throat area gets reduced in proportion
to the root gap and an over welding by 1.6mm to
a 6 mm given fillet size, the cross section area
of weld increases by a margin of 56%.
81. Balance the shrinkage forces:
Use an appropriate welding scequence.
i.e. Back step & intermittent welding techniques.
Use external force:
i.e. Tack weld, Jigs, Fixtures & Clamps.