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Topic: Heat-affected zone

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Heat-affected zone - Wikipedia, the free encyclopedia The heat-affected zone (HAZ) is the area of base material, either a metal or a thermoplastic, which has had its microstructure and properties altered by welding. The cross-section of a welded butt joint, with the darkest gray representing the weld or fusion zone, the medium gray the heat affected zone, and the lightest gray the base material. The extent and magnitude of property change depends primarily on the base material, the weld filler metal, and the amount and concentration of heat input by the welding process. en.wikipedia.org /wiki/Heat-affected_zone

ch4-3.htm The size of the heat affected zone is a function of the laser pulse duration and the material parameters such as thermal conductivity and specific heat. Associated with the heat affected zone is recast and formation of burrs. One disadvantage of the laser ablation process is that a heat affected zone is left behind where molten material re-solidified in situ or where material was sufficiently heated and cooled rapidly enough to result in embrittlement. www.me.mtu.edu /~microweb/chap4/ch4-3.htm

Fracture Toughness Behavior of Weldments with Mis-Matched Properties at Elevated Temperature The width of the heat affected zone, the distance from the fusion line to the end of the recrystallized grains, was approximately 1.85 mm (0.073 in) for all weldments. The coarse grain region of the heat affected zone was either non-existent or negligible in all specimens and a structure consisting of martensite and bainite was observed in its place. The heat affected zone consists of a region with considerable variability in the microstructure and mechanical properties of welds. www.tms.org /Students/Winners/Cretegny/Cretegny.html

Starter Topic - Welding of Stainless Steels - Corrosionsource.com Discussion Boards These steels can be welded in any heat treated condition, (annealed(a), hardened(b), stress relieved(c), or tempered) because the heat treated condition has little affect on the behaviour of the heat affected zone hardening and thus the weldability. The austenitic stainless steels are susceptible to chromium carbide precipitation in the heat affected zone which occurs between 420 degrees and 870 degrees Celsius. Heat input must be carefully controlled to minimize dilution to obtain the desired level of austenite in the deposit. www.corrosionsource.com /discuss2/ubb/Forum34/HTML/000001.html

Nuvonyx Inc. Diode Laser Systems - CW Diode Bars - Laser Welding - Laser Hardening - Laser Heat Treating - Laser Cladding- Arrays - diode pump bars  zone and heat affected zone of a titanium tube weld. Welds produced on the tube mill exhibited exceptionally smooth surfaces on both sides, very low distortion which is consistent with the small heat affected zone, and very little oxidation on the surface as a result of the good coverage by the shielding gas. Throughout the weld there was minimal variation in the hardness in the fusion and heat affected zone from the base metal. www.nuvonyx.com /applications/welding_bo.html

Microstructural change in high-temperature heat-affected zone of low-carbon weldable 13% Cr martensitic stainless steels Evidence of former Widmanstatten austenite structure was found in the weld metal and in the grain coarsened heat-affected zone of the highest alloyed steel. The microstructures that develop in the high temperature heat-affected zone (HT-HAZ) of single-pass tungsten inert gas welded plates of two different low carbon martensitic stainless steels have been investigated using optical microscopy and energy dispersive X-ray microanalysis. The region containing delta-ferrite was found to be larger in the HAZ of the highest alloyed steel. www.msm.cam.ac.uk /phase-trans/2003/dominique.html

About Welded Finned Tubes Although the tube with the HF welded fins shows a slightly less extensive heat affected zone, the affected depth is minimal in both cases when compared to other types of welding. Although studs are welded with a standard frequency welding process, the generally thicker cross-section results in a proportionately deeper heat affected zone in the tube. Post weld heat treatment of SF and HF welded Kentube fins is not considered necessary for satisfactory service, even in the extreme cases shown above, because of the superficial nature of the changes in the microstructure. www.kentube.com /typeweld.shtml

ILL : ANNUAL REPORT 2001 This behaviour depends on the order of the weld passes, at least in the thick sample; ii) the highest stress values are reached at the transition region between heat affected zone and weld pool; iii) some oscillations appear in the stress profile, especially in the weld pool. In the weld pool, the grain size is considerably larger than elsewhere, and at the boundary between heat affected zone and weld pool it can reach 500 µm [2]. have been found [3], especially inside the weld, due to the variation of the grain size and some composition and precipitation gradients between the molten zone and the heat affected zone. www.ill.fr /AR-01/p-44.htm

Welding-steel low carbon and low alloy: Materials and Processes Heat treated steels tend to lose less of their properties with friction welding as the heat is localized and limited to a narrow zone. As these steels cannot develop exceptional mechanical properties neither by heat treatment nor by thermo-mechanical means there is no way to damage their basic properties by heating to melt or to weld them. Hardened and tempered low alloy steels are likely to lose their mechanical properties (strength and hardness) during welding, but not only that: they may be rehardened by heat near the weld, and crack. www.welding-advisers.com /Welding-steel.html

Heat Affected Zone The region next to the fusion zone (weld pool) where microstructural changes have occurred is known as the heat affected zone Such microstructural changes may affect the mechanical properties of the weld and need to be controlled (e.g. www.staff.ncl.ac.uk /s.j.bull/mmm373/WMICRO/tsld005.htm

Publications - American Horticultural Society - Heat Zone Map Heat damage can first appear in many different parts of the plant: Flower buds may wither, leaves may droop or become more attractive to insects, chlorophyll may disappear so that leaves appear white or brown, or roots may cease growing. Air movement in a garden is affected by natural features such as proximity to bodies of water and the presence of surrounding vegetation, as well as structures such as buildings and roads. The accuracy of the zone coding can be substantially distorted by a lack of water, even for a brief period in the life of the plant. www.ahs.org /publications/heat_zone_map.htm

The L.S. Starrett Company - Bi-Metal Unique Saw Technology The heat-affected zone is a stressed area that can cause teeth to shear from the carrier. In diffusion bonding, with HSS wires bonded to the sides of the strip, the contact area is increased by 170 percent, and the fusion zone is parallel to the teeth. Caron describes solid-state diffusion bonding as a combination of low heat and high pressure that applies HSS wires to both sides of the carrier with pressure rolls in an inert atmosphere. www.starrett.com /pages/1075_bi_metal_unique_saw_technology.cfm

Application notes - Welds Under many circumstances the bulk of the anodic dissolution is within the heat affected zone (haz). Conventional electrochemical testing in which a sample of the weld is immersed and used as the working electrode will only reveal a low overall net rate not the high rate in the heat affected zone. a pipeline) a weld metal and an area of heat affected metal. www.potentiostat.com /tech/apn-welds.shtml

Introduction to Flamecutting The heat entering the workpiece usually causes two problems: a tendency to warp and a heat-affected zone that upsets the properties of the steel. The plasma process does not usually create as deep a heat-affected zone, but it is not entirely absent and the type of metallurgical changes may be different due to the various plasma gasses used. Although plenty of heat is generated inside the cut to heat the metal adequately, the upper surface tends to stay cooler because it is heated only from the underside. www.torchcutter.com /intro.htm

9.5.4 The heat-affected zone may become susceptible to stress-corrosion cracking, particularly the high-strength alloys, and expert advice is necessary concerning the suitability of a particular alloy for a certain environment after welding. 1. Thermally treat the structures to effect a re-solution of the chromium carbide; this is often impractical in large structures unless local heat treatment is employed, but is not always satisfactory since a sensitised zone could be produced just outside the local thermally treated region. During welding some zone in the vicinity of the weld area is inevitably raised within the sensitisation temperature range and the degree of severity of sensitisation will be dependent on a number of process factors that determine the time in this temperature range, e.g. www.mtm.kuleuven.ac.be /Research/Mentor-C/shreir_demo/control/vol9_5_4.htm

World Intellectual Property Organization The microcrack is quenched at a quenching region that is contained within the heat affected zone by passing fluid from a quenching nozzle onto the substrate. In accordance with the present invention, the quenching region is contained within the heat affected areas shown in FIGS. This helps achieve the desired high gradients in the quenching region, places tensile forces behind the quenching region, and creates a heated zone behind the nozzle that can be used to evaporate any residual liquid from the nozzle. www.wipo.int /ipdl/IPDL-CIMAGES/view/pct/getbykey5?KEY=01/38039.010531&ELEMENT_SET=DECL

Patent 4978917: Method for nondestructive measurement of heat affected zone of identification code on nuclear fuel rod The depth of the change or heat affected zone is dependent on the amount of power generated by the laser which is used to etch the bar code on the tube. In order to keep the depth of the heat affected zone of the tube 16 within the desired limit, preferably, the laser power is applied at a marking speed of from about 5000 to 9000 mils per second and at a repetition rate of from about 25,000 to 34,000 KHz. There is a direct correlation between the mV output and the depth of the heat affected zone, i.e., the higher the mV output the deeper the depth of the heat affected. www.freepatentsonline.com /4978917.html

Stress Corrosion Cracking in District Heating Pipes Cracks are not only present in the weld and the heat-affected zone, but also at a distance of approximately 12 mm from the weld, an area which does not lie directly in the heat-affected zone. The high residual stresses adjacent to the weld and the possibly slightly more sensitive structure in the heat-affected zone, in combination with the strain rates resulting from temperature fluctuations in the return pipe, will cause increased intergranular SCC in the zone adjacent to the weld. Due to the temperature changes in the return pipe in the event of heat consumption, intergranular SCC is initiated preferentially in the zone adjacent to the weld joints, where the axial residual stresses are also highest. home.planet.nl /~whuijbregts/publications/breda/breda2.htm

CMS—Welding Science Solidification in the fusion zone and solid-state phase transformations in the heat-affected zone are responsible for dramatic changes in the microstructure and properties of the welded joint. Surrounding the fusion zone is a heat-affected zone, where the substrate is heated to temperatures up to the melting point of the metal being joined. Adjacent to the immediate weld area, or fusion zone, is the heat-affected zone (HAZ). www-cms.llnl.gov /s-t/welding.html

Microstructure Classification of Friction Stir Welds The term heat affected zone is now preferred, as this is a direct parallel with the heat affected zone in other thermal processes, and there is little justification for a separate name. Heat affected zone (HAZ): In this region, which clearly will lie closer to the weld centre, the material has experienced a thermal cycle which has modified the microstructure and/or the mechanical properties. Thermo-mechanically affected zone (TMAZ): In this region, the material has been plastically deformed by the friction stir welding tool, and the heat from the process will also have exerted some influence on the material. www.twi.co.uk /j32k/unprotected/band_1/fswqual.html

Laser brazing for ceramic-to-metal joining - US Patent 5407119 The simplest approach to laser brazing is to heat the substrate or base metal adjacent to the joint and to rely upon thermal conductivity to heat the joint and filler metal to the brazing temperature. In this process, a thin layer of the substrate is rapidly heated well into the austenitizing temperature by laser heating and subsequently cooled at a very fast rate, due to self quenching by conduction into the bulk part, to form a martensitic structure. However, supplementary heating and control of the heating and cooling cycles have enabled sound welds to be made in some ceramics. www.patentstorm.us /patents/5407119.html

IngentaConnect Effects of welding heat input on microstructure and hardness in h... By using a numerical simulation technique, the effects of welding heat input on microstructure and hardness in HAZ of HQ130 steel are studied. There are two parts of the heat input in gas-metal arc welding (GMAW): one is the arc heat flux and the other is the heat content of filler metal droplets. A numerical model of fluid flow and temperature field in GMAW is established according to the new mode of arc heat flux distribution. api.ingentaconnect.com /content/iop/msmse/2001/00000009/00000001/art00303

Edm Heat Affected Zone www.FoxMachining.com Immediately below the recast layer is the Heat Affected Zone (HAZ) which is partially affected by the heat and temperatures created during the EDM process. where it is needed, minimizing the heat affected zone surrounding the area being cut. Waterjet cutting is much faster than wire EDM and does not leave a "heat affected zone" like laser or plasma cutting. www.foxmachining.com /k/edmheataffectedzone

Metal and Metallurgy engineering - Yield strength change in welded heat affected zone! If you can not subsequently heat treat the assembly, run a couple of low power postweld laser passes to temper the weld and heat affected zone. But the metal in the weld zone does get very hot and once it cools down, it becomes very brittle and hard, because of untempered martensite. Hello, I have a part that has three metal sheets made of 1075 steel laser welded together on the outer edges to form an enclosed volume of air that is compressible to take care of some pressure waves in a tube and regulate the dynamics. www.eng-tips.com /viewthread.cfm?qid=70131

Sec. 8 Introduction When Ductile Iron castings are repaired or joined by fusion welding their high carbon content can cause the formation of carbides in the fusion zone (FZ) and martensite in both the FZ and heat affected zone (HAZ) adjacent to the FZ. The high carbon content of Ductile Iron can lead to the formation of carbides in the fusion zone (FZ) and martensite in both the FZ and heat affected zone (HAZ) adjacent to the FZ unless correct procedures are followed. In addition to the elimination of structural changes in the base metal, the absence of heat input in adhesive bonding also eliminates the problem of distortion and permits the bonding of Ductile Iron to a wide variety of metallic and non-metallic materials, regardless of their melting points or physico-chemical properties. www.ductile.org /didata/Section8/8intro.htm

Research Plan of Evaluating NU-Cu Steel Received From Oregon Steel Mills The main issues are yield strength and fracture toughness of the base steel and the heat affected zone. Welding to Prepare Specimens for Investigation of Heat Affected Zone of NU Steel to be done at Northwestern under direction of Val Malin. Welding to be done without preheat or post heat. www.iti.northwestern.edu /research/a_projects/fine_steel95c.html

American Welding Society Presents The Weld Heat-Affected Zone Conference At The 2005 AWS Welding Show Miami—March 7, 2005: The American Welding Society (AWS) will offer The Weld Heat-Affected Zone (HAZ) Conference on Monday, April 25, 2005, at the 2005 AWS Welding Show. The American Welding Society is the largest organization in the world dedicated to advancing the science, technology, and application of welding and allied processes, including joining, brazing, soldering, cutting, and thermal spraying. Register for the HAZ Conference by calling 800-443-9353, ext. www.aws.org /pr/mar7-2005.html

Todd's First Frame The heat affected zone is the part of the tube in which the crystaline structure of the metal is changed to a slightly weaker form. This gives the weld that sought after 'stacked dime' look, and also lessens the heat affected zone. Brazers claim that the lower heat required for this type of work creates a lesser heat affected change, while welders believe that the shorter duration of more intense heat is less destructive to the structure. www.frenchtown.com /toddsart/frame.html

Steel Dictionary - H The part of the parent metal which is metallurgically affected by the heat of welding or thermal cutting but not melted. The steel is heated and then cooled as necessary to provide changes in the structural form that will impart the desired characteristics. One heat of steel will be used to cast several slabs, blooms or billets. www.mesteel.com /dictionary/h.htm

Technical Information about Waterjet cutting technology Plasma cutting produces a large Heat Affected Zone of about an inch deep. Abrasive Waterjet is a cold cutting process that induces no heat, or stress. Waterjet is a cold cutting process which produces no heat. www.precisionwj.com /technical.html

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