The Heat Affected Zone.ppt

8/9/2019 The Heat Affected Zone.ppt

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THE HEAT AFFECTED ZONE

Nick Kostrikin

Liz Lehman


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Objectives:

Analyze the heat affected zone (HAZ) created by3 types of weldin and ! different coolin rates

"dentify any chanes in the properties of thematerial characteristic of each type of weldin

"dentify any chanes in the properties of thematerial based on the method of coolin #sedafter weldin


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Parent metal:

Low carbon steel A$%& '

*asy to form and weld

&a+ carbon content of ,-.' wt/ ,-3, 0 ,-, wt/ &

&a+ phosphoro#s content of ,-,1 wt/

''2,,, psi tensile strenth 3,2,,, psi yield strenth

3,/ elonation


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TIG welding:

Noncons#mable t#nsten electrode is #sed to

create an arc

"nert as #sed to shield the weld zone from

contaminants %emperat#re of electric arc e+ceeds ',,4 5

%he intense heat is foc#sed on a 6ery small area

%he process is 7#ick2 clean2 and free of sla andsp#tter


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A look at %"8 weldin9


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IG welding:

A cons#mable wire is #sed to establish an arcand as a filler material in the weld zone

:an be #sed with inert as or fl#+ cored fillerwire to shield the weld zone from contaminates

As with %"8 weldin2 an intensely hot electric arcis created with the filler wire

As with %"8 weldin2 a minim#m amo#nt ofmaterial is necessary to prod#ce a weld ofma+im#m strenth


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&"8 weldin .,.9


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&ore &"89


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Gas welding:

;razin is a process of as weldin


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Ancient and modern forms of as weldin9


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9alternati6e forms of as weldin


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8ettin the ?ihtflame9


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Pr!ced"re:

@eld ! sets of metal samples with %"82 &"8 and;?AZ"N8


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E#am$les !% s!me TIG welds&


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Hardness $l!t !% t'e TIG welded sam$le

(ater )"enc'ed sam$le

E cycles to fail#re2 crack at .,mm

Air c!!led sam$le

.. cycles to fail#re2 crack at .=mm


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O"r IG welded sam$les&


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(ater )"enc'ed sam$le

E! cycles to fail#re2 crack at mm

Air c!!led sam$le

=' cycles to fail#re2 crack at .mm

Hardness $l!t !% t'e IG welded sam$le


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O"r *ra+ed welded sam$le&


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Air c!!led sam$le

cycles to fail#re2 crack at welded >oint

(ater c!!led sam$le

1 cycles to fail#re2 crack at welded >oint

"nconcl#si6e ?es#lts FF


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Hardness c!m$aris!n !% TIG and IG welding&


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E%%ects !% di%%erent t,$es !% welding:

%"8 weldin created a 6ery stron weld with oodhardness and d#ctility

&"8 weldin created a similarly stron weld with slihtly

reater hardness 6al#es2 less d#ctility2 and a smallerheat affected zone than %"8

8as weldin with brass created a weld of ins#fficient

strenth hence its strenth and d#ctility co#ld not becompared to the two types of arc weldin


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E%%ects !% di%%erent met'!ds !% c!!ling:

%ypically the rain str#ct#re ad>acent to the weld hasrelati6ely lower hardness and reater d#ctility associatedwith a coarse rain size- @ater 7#enchin decreases thesize of the rain str#ct#re2 th#s raisin the hardness-

%he ne+t zone consists of a band of finer rains at thecritical temperat#re- %his zone is relati6ely harder andless d#ctile than the first zone and is more prone tocrackin- @ater 7#enchin tends to harden this zone andca#ses cracks to occ#r closer to the weld than air cooled

samples- %he third zone consists of a normal rain str#ct#re

resemblin those of the parent metal and is f#rthest fromthe weld-


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%H* *N

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The Heat Affected Zone.ppt