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

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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

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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

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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

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Phase Diagra When Interstitial Carbon Alloys with Iron


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Welding Metallurgy

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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,

4d Welding Metallurgy

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