4d Welding Metallurgy
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Transcript of 4d Welding Metallurgy
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Welding Metallurgy
1998/MJ1/MatJoin3/1
Welding Metallurgy
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Welding Metallurgy
1998/MJ1/MatJoin3/2
Lesson Objectives
When you finish this lesson you will
understand:• The various region of the weld where
liquid forms
• Mechanisms of cracking associated withthese regions
Learning Activities
1. Read Handook !!1"#$1%#
%. &iew 'lides(
#. Read )otes*
+. ,isten to lecture
-. o on$line
workook
/. o homework
Keywords
0om!osite one* Hot 0racking* 0onstitutional 'u!ercooling*
2nmi3ed one* 4artially Melted one* 0onstitutional ,iquation*
http://we019.eng.ohio-state.edu/wenc/wenc.cfmhttp://we019.eng.ohio-state.edu/we300/w300t/we300.htm
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Welding Metallurgy
1998/MJ1/MatJoin3/3
Materials Behavior
Weldability is the capacity of a material to be
welded under the fabrication conditions
imposed, into a specific, suitably designed
structure, and to perform satisfactorily in the
intended service. Materials compatibility
Process Response to stress and strain during welding
Introduction
0.1.1.5.0.1.!5.1"
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Welding Metallurgy
1998/MJ1/MatJoin3/4
Basic Regions of a Weld
Fusion Zone # areathat is completely
melted
Heat-Affected Zone #
portion of the basemetal not melted but
whose mechanical
properties and
microstructure were
affected by the heat of
the $oining process
ase Metal
%usion &one
'eat#affected &one(ase metal
Introduction
0.1.1.5.0.".!5.1"
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!o"#osite Zone !oncerns
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Welding Metallurgy
1998/MJ1/MatJoin3/$
Solidification (Hot) Cracking
)olidification *hot+ cracing re-uires ow ductility material
'igh tensile contraction stress
)olidification occurs over a range of temperature ow melting point intergranular films
)ulfur, phosphorus, boron
Prevention by ow /, ), P levels ncreased Mn
Cracking in Welds
0.1.1.5.".1.!5.1"
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%ntroductory Welding Metallurgy&
AW'& 19(9
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Welding Metallurgy
1998/MJ1/MatJoin3/9
Phase Diagra When Interstitial Carbon Alloys with Iron
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Welding Metallurgy
1998/MJ1/MatJoin3/1$
Perils of Welding Free-Machining Steels
)olidification cracing
due to impurity elements )ulfur, phosphorus, boron
ead doesn2t seem tocause a problem, e.g.
1"13
mpurity segregation at
weld centerline creates
low ductility area /ombines with shrinage
stress to cause cracing
0.1.1.5.".1.!5.1"
!teel
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Welding Metallurgy
1998/MJ1/MatJoin3/1(
Manganese Can Prevent Solidification Cracking
Manganese combines with sulfur to form Mn) particles
4se a filler metal with higher manganese to absorb sulfur
)*(+'-3 !o"#osition )*(+-$0.0 # 0.15 carbon 0.06#0.150.! # 1.3 manganese 1.3 # 1.75
0.35 # 0.6 silicon 0.7 # 1.150.0" phosphorus 0.0"
0.05 sulfur 0.050.05 copper 0.5
!teel
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"urn to the #erson sitting ne$t to you and discuss %& in'()
• Constitutional su#ercooling works *or alloys with K values
less than &'+ but what ha##ens *or alloys with K greater
than &'+ %I'e' rising liguidus with increasing te#erature(,
Can you draw the three corves,
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,n"ied Zone !oncerns,n"ied Zone !oncerns
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.artially Melted Zone !oncerns
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"urn to the #erson sitting ne$t to you and discuss %& in'()
• What se-uence o* event needs to take #lace *or
constitutional li-uation to result in li-uid *ils, Can we use
a #hase diagra to #redict i* this will ha##en or not,