scholarly journals PENGARUH PENDINGINAN MEDIA AIR DAN OLI PADA HEATTREATMENT SAMBUNGAN LAS METODE SMAW TERHADAP KEKUATAN LOGAM YANG DIHASILKAN

2018 ◽  
Vol 8 (2) ◽  
pp. 196
Author(s):  
Asep AR Ruchiyat
Keyword(s):  
Heat Treatment ◽  
Weld Metal ◽  
Cooling Water ◽  
Welding Process ◽  
Raw Material ◽  
Natural Phenomenon ◽  
Free Air ◽  
Mechanical Ability ◽  
The Difference ◽  
Cooling Media

Abstract Welding is a method of metal extension that utilize the Penetration of heat produced. Heat and the freeze of a metal extension is a natural phenomenon, where that process works based on the difference of temperature. The cooling temperature that work so fast creating diverse structure as the result that the mechanical ability of a metal changes.                This research purpose is to find out to what extent heat treatment with water and oil cooling media gives effect to the result of SMAW weld, considering processes changes in metal are very sensitive towards mechanical ability.                 Hardness testing in raw material that has been done gives result of 46.9 with an average hardness in the normal welding process of 48 HRB or increased by 2.34%. This value indicates that the welding process will have an impact on the increase in hardness of the weld metal. Then the weld metal heat treatment process at 850oCwith normal cooling of free air decreases the weld metal hardness by 43.5 HRB or 7.24% under raw material. While the quenching process carried out with water and oil cooler has an impact on increasing the hardness above heat treatment, normal cooling is 4.36% and 3.19% lower to the raw material. From this description it can be concluded that quench accelerates the rate of cooling and increase hardness by 4.36%. Key words: welding SMAW, heattreatment, cooling water and oil, hardness metal   

scholarly journals Pemanfaatan limbah piston bekas sebagai filler metal aluminium pada pengelasan oxy-acetylene

2017 ◽  
Vol 7 (2) ◽  
Author(s):  
Z. Nurisna
Keyword(s):  
Tensile Strength ◽  
Weld Metal ◽  
Filler Metal ◽  
Welded Joint ◽  
Cooling Water ◽  
Welding Process ◽  
Raw Material ◽  
Porosity Defects ◽  
Si Content ◽  
Test Loading

The abundance of waste piston used so far has not been utilized properly. Users of this piston waste can be used as an oxy-acetylene welder filler. Las oxy-acetylene has been widely used for welding on various types of aluminum product repair, one of which is welding machine block. Machine blocks in their use often suffered damage to the cooling water circulation path and broken crack and broken. Welders and repair shops that repair these damages do not have standardized standards in the use of weld fillers, but they do filler selection based solely on experience including in determining the weld filler. The purpose of this research is to know the effect of piston waste which is used as raw material of weld filler to tensile strength and hardness of welded block result of machine using oxy-acetylene welding. Welding is done by an experienced welder. The welding results are tested for tensile strength and hardness distribution test. The welded joint with the chemical composition of filler which is almost equal to base metal has the highest tensile strength. The tensile strength of the welded joint tension test is in the weld metal region due to defects in the weld metal, especially the porosity defects that are formed during the welding process so that the tensile test loading is concentrated on the defect. While the highest hardness on the weld is in the filler metal with the highest percentage of Si content.

Effect of Postweld Heat Treatment Conditions on Microstructure of 9Cr-1Mo-V Steel Welds for Pressure Vessel

2017 ◽  
Author(s):  
Hidenori Terasaki ◽  
Tomohiro Tanaka ◽  
Masamitsu Abe ◽  
Mitsuyoshi Nakatani
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Weld Metal ◽  
Postweld Heat Treatment ◽  
Pressure Vessels ◽  
Dislocation Network ◽  
Precipitation Behavior ◽  
Treatment Conditions ◽  
Scanning Transmission ◽  
The Difference

We investigated the effects of post-weld heat treatment conditions on the microstructure of the multi-pass submerged arc weld metal of 9Cr-1Mo-V steel used in pressure vessels. The microstructural properties were analyzed under three conditions (as-weld, Larson-Miller parameter (LMP) = 21.38 × 103, and LMP = 21.99 × 103). The precipitation behavior was observed using scanning electron microscopy, and the difference in precipitation behavior in the “as-welded” and “reheated” regions of the prepared multi-pass weld metal was clarified at the different LMP values. The precipitate was analyzed using scanning transmission electron microscopy. An oxide and two types of precipitates were identified, and a dislocation network pinned by MX-type carbides was visualized under the low-LMP condition. The effects of LMP on the effective grain size and dislocation amount were also evaluated using electron back-scattering diffraction. All microstructural change along the LMP had a positive effect on the toughness of weld metal.

Effect of the FCAW Welding Process and Post Weld Heat Treatment on the Properties and Microstructure of the Weld Joints of Heat Treated 4330V Steel

2015 ◽  
Vol 809-810 ◽  
pp. 437-442
Author(s):  
Jacek Górka ◽  
Michał Miłoszewski
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Weld Metal ◽  
Heat Input ◽  
Large Diameter ◽  
Welding Process ◽  
Post Weld Heat Treatment ◽  
High Toughness ◽  
Interpass Temperature ◽  
Weld Heat

4330V is a high strength, high toughness, heat treatable low alloy steel for application in the oil, gas and aerospace industries. It is typically used for large diameter drilling parts where high toughness and strength are required. The research describes the effect of preheat temperature, interpass temperature, heat input, and post weld heat treatment on strength, hardness, toughness, and changes to microstructure in the weld joint. Welding with the lower heat input and no post weld heat treatment resulted in optimal mechanical properties in the weld metal. Austempering at 400 °C resulted in optimal mechanical properties in the HAZ. Increasing preheat and interpass temperature from 340 °C to 420 °C did not improve Charpy V-notch values or ultimate tensile strength in the weld metal or heat affected zones. The higher temperature increased the width of the heat affected zone. Austempering at 400 °C reduced HAZ hardness to a level comparable to the base metal. Both tempering and austempering at 400 °C for 10 hours reduced toughness in the weld metal.

Variables Affecting Fracture Toughness of Welds in T-K-Y Connections

2014 ◽  
Author(s):  
Radhika Panday ◽  
Shenjia Zhang ◽  
Jon Ogborn ◽  
Badri K. Narayanan
Keyword(s):  
Heat Treatment ◽  
Fracture Toughness ◽  
Transition Temperature ◽  
Weld Metal ◽  
Welding Process ◽  
Post Weld Heat Treatment ◽  
Factors Affecting ◽  
Brittle Transition ◽  
Brittle Transition Temperature ◽  
Ductile To Brittle Transition

Fracture toughness of tubular welded joints is one of the critical factors affecting the structural integrity and reliability of offshore structures, such as platforms and subsea pipelines. The factors affecting the design fracture toughness of these structures are related to, both, the welding process as well as the chemical composition of the weld metal. The welding process in this application typically comprises of depositing weld metal in the tubular joints of varying thicknesses through series of weld passes. The number of weld passes required for welding these joints subjects the weld metal to repetitive cycles of heating and cooling. The effect of the thermal cycling introduces significant heterogeneity in the microstructure. This is further exacerbated by the presence of micro-alloying elements such as Niobium (Nb) and Vanadium (V) that form complex carbides, nitrides and carbo-nitrides during post weld heat treatment (PWHT). The focus of this work is to evaluate the effect of micro-alloying elements on the ductile to brittle transition temperature and the mode of fracture at temperatures relevant to offshore applications. A threshold Nb and V level has been determined for achieving acceptable weld metal toughness. The improvement in the fracture toughness using this approach has been quantified by Charpy V-Notch (CVN) and Crack Tip Opening Displacement (CTOD) measurements. The Ductile to Brittle Transition Temperature (DBTT) has been shown to be shifted to lower temperatures by 25 °C after post weld heat treatment in the welds where the total amount of Nb and V are controlled to less than 40 ppm. A wet precipitate extraction technique was used to extract precipitates from the welds to establish the presence of fine Nb rich precipitates in the welds with the higher DBTT. The weld deposited with controlled levels of Nb and V was further tested in different joint configurations and base plate thickness. The fracture toughness was evaluated by CTOD testing of the weld in two different thicknesses (50 mm and 70 mm). Increased specimen thickness resulted in lower CTOD values.

Weld Hardness Study of P91 Welded Pipes with Post Weld Heat Treatment for Elevated Temperature Application in Power Plants

2015 ◽  
Vol 1115 ◽  
pp. 503-508 ◽  
Author(s):  
Muhammad Sarwar ◽  
Mohd Amin bin Abd Majid
Keyword(s):  
Heat Treatment ◽  
Power Plant ◽  
Weld Metal ◽  
Creep Strength ◽  
Power Plants ◽  
Thermal Power ◽  
Base Material ◽  
Welding Process ◽  
Post Weld Heat Treatment ◽  
Weld Heat

The creep strength-enhanced ferritic (CSEF) steels are undergoing an encouraged use around the world especially in power plant construction. On construction sites, it has always been the target to have no problems in welded joints but premature failures are being encountered. The primary reason of these premature failures is found to be the improper heat treatment that is mandatorily carried out to achieve the required weld hardness. Weld hardness has close relationship with creep strength and ductility of the welded structures. Hence it is important for any weld to achieve certain level of weld hardness. This study aims at ascertaining the importance of Post Welding Heat Treatment (PWHT) in achieving the required hardness in creep-strength enhanced ferritic (CSEF) materials.The study was carried out on the welding of alloy steel ASTM A335 Gr. P-91 with the same base material (ASTM A335 Gr. P-91) by Gas Tungsten Arc Welding (GTAW) process using ER90S-B9 filler wire with pre-heat of 200oC (min) and inter-pass temperature of 300oC (max). After welding, the joints were tested for soundness with Radiography testing. Induction heating was used for heat treatment of P91 pipes during welding and post weld heat treatment. The effect of Post Weld Heat Treatment (PWHT) was investigated on the Weld metal and the Heat Affected Zones (HAZ) by hardness testing. It is perceived that the scattered and higher hardness values, more than 250HB in 2” P91 pipes in the weld metal and in the heat affected zones, can be brought into the lower required level, less than 250HB, with an effective post weld heat treatment at 760°C for 2hrs.It is concluded that PWHT is the most effective way of relieving the welding stresses that are produced due to high heat input in the welding process and to achieve the required level of hardness in the weld as well as in the heat affected zones (HAZ) in thermal power plant main steam piping.

scholarly journals PENGARUH MEDIA PENDINGINAN TERHADAP KEKERASAN DAN STRUKTUR MIKRO HASIL PENGELASAN OXY ACETYLENE PADA MATERIAL BAJA ST-37

2017 ◽  
Vol 5 (2) ◽  
Author(s):  
Made Angga Priadi ◽  
I Nyoman Pasek Nugraha ◽  
Gede Widayana
Keyword(s):  
Weld Metal ◽  
Base Metal ◽  
Heat Affected Zone ◽  
Quantitative Research ◽  
Welding Process ◽  
Air Cooling ◽  
Water Cooling ◽  
Independent Variable ◽  
The Mean ◽  
Cooling Media

Media pendingin merupakan suatu substansi yang berfungsi dalam menentukan kecepatan pendinginan yang dilakukan terhadap material yang telah diuji dalam perlakuan panas. Penelitian ini bertujuan untuk mengetahui tingkat kekerasan dan pengamatan struktur mikro material baja ST-37 yang dipengaruhi media pendinginan air, udara dan oli serta penelitian ini dapat memberikan bahan referensi bagi lingkup pendidikan teknik mesin dan sebagai acuan di dunia industri dalam menggunakan media pendingin pada proses pengelasan. Adapun jenis metode yang digunakan dalam penelitian ini adalah metode penelitian eksperimen. Terdapat dua jenis variable yang digunakan dalam penelitian ini yaitu variabel bebas yang berupa media pendingin air, media pendingin udara dan media pendingin oli dan variabel terikatnya berupa sifat kekerasan. Dari hasil penelitian yang telah dilakukan dimana kekerasan daerah logam induk dengan media pendingin air memperoleh nilai rata-rata sebesar 63,10 Kg/mm2, pendingin udara memperoleh nilai rata-rata sebesar 65,61 Kg/mm2, dan media pendingin oli memperoleh nilai rata-rata sebesar 62,68 Kg/mm2. Kekerasan pada daerah HAZ dengan media pendingin air memperoleh nila rata-rata sebesar 68,49 Kg/mm2, media pendingin udara memperoleh nilai rata-rata sebesar 71,05 Kg/mm2 dan media pendingin oli memperoleh nilai rata-rata sebesar 70,34 Kg/mm2. Kekerasan pada daerah logam las dengan media pendingin air memperoleh nilai rata-rata sebesar 60,99 Kg/mm2, media pendingin udara memperoleh nilai rata-rata sebesar 61,79 Kg/mm2 dan media pendingin oli memperoleh nilai rata-rata sebesar 60,79 Kg/mm2. Berdasarkan dari hasil yang telah didapatkan baik pada logam induk, daerah HAZ dan logam Las dimana tingkat kekerasan yang lebih baik diperoleh dari proses pendinginan udara dibandingkan dengan media pendingin air dan media pendingin oli dari proses pengelasan oxy acytelene.Kata Kunci : Baja ST-37, Kekerasan Material, media pendinginan. The cooling media is a substance which has a function to determine the speed refrigeneration which carried out of the material that has been tasted by heat treatment. The objective of the research is to know the level of hardness and the observation of steel ST-37 material which is affected by cooling media such as water, air, and oil. Also this research may give a reference for Engineering Department of Education and industry in using cooling media for welding process. There is a method that use in this research, that is called quantitative research. There are two variables that use in this research. Independent variable and dependent variable. An independent variable are water, air, and oil cooling media. On the other hand, a dependent variable is nature of hardness. In this research the researcher got a results where the mean of hardness of the base metal area with the water cooling media is 63.10 Kg/mm2, in air conditioning is 61Kg/mm2, and the oil cooling is 62.68 Kg/mm2. The mean of a hardness in Heat Affected Zone (HAZ) by water cooling media 68,49 Kg/mm2, air cooling media is 71,05 Kg/mm2 and an air cooling is 70,34 Kg/mm2. The mean of Hardness in the weld metal area with water cooling media is 60,99 Kg/mm2, air-cooling media is 61,79 Kg/mm2 and oil-cooling media is 60,79Kg/mm2. Based on the result which has been gotten from base metal, Heat Affected Zone (HAZ), and weld metal where the best hardness level is obtained from air-cooling process rather than water cooling media and oil cooling media from oxy acytelene welding process.keyword : Cooling media, steel ST-37, hardness properties.

Characterization of Microstructure and Mechanical Properties of AA2219-O and T6 Friction Stir Welds

2019 ◽  
Vol 969 ◽  
pp. 205-210 ◽  
Author(s):  
D. Venkateswarlu ◽  
Muralimohan Cheepu ◽  
P. Nageswara Rao ◽  
S. Senthil Kumaran ◽  
Narayanan Srinivasan
Keyword(s):  
Heat Treatment ◽  
Welding Process ◽  
High Strength ◽  
Friction Stir ◽  
Microhardness Distribution ◽  
Treatment Conditions ◽  
Heat Treated ◽  
The Difference ◽  
Aluminum Alloy 2219 ◽  
Failure Location

In the present study, aluminum alloy 2219 of two different heat treatment states were selected and welded using the friction stir welding process to evaluate the effect substrate on the joint properties. The microstructural observations have exhibited the difference in their characteristics between two heat treatment conditions of 2219-O and T6 conditions. The tensile strength of the AA2219-T6 joints much higher than the AA2219-O joints. Consequently, the microhardness distribution across the different zones varying with two different heat treated conditions. The failure locations and fracture surface features are revealed the significant differences among these two heat treated conditions with the change in their failure location and the fracture morphologies. The optimal welding conditions were analyzed to determine the high strength of the welds with excellent metallurgical properties of the welds.

Weld Repair of C, Cr-Mo Cokedrums (and Pressure Vessels) Without PWHT

2017 ◽  
Author(s):  
Alwyn Kaye ◽  
Patrick Lester ◽  
Darren Barborak
Keyword(s):  
Heat Treatment ◽  
Weld Metal ◽  
Low Cycle Fatigue ◽  
Welding Process ◽  
Fatigue Cracking ◽  
Pressure Vessels ◽  
Post Weld Heat Treatment ◽  
Original Design ◽  
Controlled Deposition ◽  
Weld Heat

Many of the Cr{1-1/4 to 2-1/4}-Mo{1/2 to 1} pressure vessels in the refining and petrochemical industries such as process reactors, distillation columns, separators, pressurized storage vessels, and heat exchangers are typically vertical columns, most often supported by a circular skirt. Typically, design considerations for these vessels and support skirts are for operating under continuous “steady-state” conditions, where temporary stresses due to short-term “transient” events such as start-up and shutdown are often ignored. Consequences of dynamic and cyclic loading play a very significant role in their life and performance. For Coke drums, survey data from API shows that the skirt-to-drum attachment weld and adjoining area appears to be the most problematic, frequently experiencing low-cycle fatigue cracking due to concentrated stresses. A methodology for repairing the skirt attachment weld of Cr-Mo pressure vessels is provided. When designing a repair approach, consideration should include material and aged condition, extent and location of defects, welding process and consumables, and codes, standards, and regulatory guidelines. When repair by weld metal buildup to rebuild a skirt-attachment weld configuration is considered, weld procedure qualification and adequate mock-ups should be performed in order to ensure a sound repair. Further, when invoking a code compliant repair without post-weld heat treatment by controlled deposition welding or temper bead techniques, proper training of welder operators should be conducted to ensure the techniques are implemented properly. A case study is provided for a Coke drum, where the original design and fabrication of the skirt attachment included an initial SAW weld metal buildup on the 2.25Cr (P5A) cone followed by an SMAW/GTAW attachment weld to the 1.25Cr skirt (P4). During a plant shutdown, a surface breaking crack was detected in the skirt to shell attachment weld by Dye Liquid Penetrant Testing (D-LPT) and confirmed with Magnetic Particle Testing (MPT). Subsequent examination by Phased Array Ultrasonic Testing (PAUT) discovered a large number of volumetric indications, oriented towards the knuckle section internally. The repair approach consisted of 1) Completely remove the existing skirt and the attachment weld (knuckle) in segments, 2) Inspect the cone for remaining flaws, 3) Excavate and repair flaws in cone using temper bead technique, 4) Rebuild knuckle area for skirt to cone attachment with an increased radius using temper bead welding techniques, 5) Install new skirt sections using controlled deposition welding technique. Temper Bead and Controlled Deposition repair welding techniques were utilized to avoid conventional post-weld heat treatment requirements, significantly improving the turn-around time in the field.

scholarly journals ANALISIS KUALITAS REPAIR WELDING CAST WHEEL ALUMINIUM MENGGUNAKAN METODE PENGELASAN OKSI-ASETILIN DENGAN PERLAKUAN PREHEATING DAN POST WELD HEAT TREATMENT

2019 ◽  
Vol 1 (1) ◽  
pp. 31
Author(s):  
Aftoni Heri Septian Pamungkas ◽  
Budi Harjanto ◽  
Indah Widiastuti
Keyword(s):  
Heat Treatment ◽  
Chemical Composition ◽  
Welding Process ◽  
Primary Phase ◽  
Post Weld Heat Treatment ◽  
Raw Material ◽  
Hardness Tester ◽  
Primary Si ◽  
Descriptive Method ◽  
Weld Heat

<p><em>The aims of this research are to find out chemical composition, micro structure, the hardness </em><em>level</em><em>, and the strength impact of raw material and after welding using </em><em>preheating and post weld heat treatment </em><em>on cast wheel aluminum</em><em>.</em><em> Those data were analyzed using comparative descriptive method. The equipments used for measuring the chemical composition, microstructure, the hardness </em><em>level</em><em>, and the strength impact are as following: Spectrometer Metal Scan, Olympus Metallurgy</em><em> </em><em>Microscope, Vi</em><em>k</em><em>ers Hardness Tester and Charpy Tester. Based on the experiment results, it can be concluded that the chemical composition of the main constituent of cast wheel aluminum is 7,41% Si,</em><em> </em><em>which can be categorized in the aluminum alloy AA4343 series. The experiment results showed a decrease in the extent of the microstructure of primary Si phase after welding.</em><em> Si primary phase were spread well around the surface of </em> <!--?mso-application progid=&quot;Word.Document&quot;?--> 12α"&gt; -Al<em> </em><em>but the result Si </em><em>after oxy-acetylene </em><em>welding process </em><em>w</em><em>it</em><em>h</em><em> preheating and </em><em>PWHT indicates that the primary Si phase is reducing so that the α-Al phase is dominating</em><em>. </em><em>The hardness </em><em>level</em><em> on the welding result decreased from raw material amounted to 103.381 kgf/mm<sup>2</sup> be 40.112 kgf/mm<sup>2</sup> in the welding area and 44.378 kgf/mm<sup>2</sup> in area Heat Affected Zone (HAZ). The strength impact number on welding</em><em> </em><em>area showed a slight increase from the raw material areas of 0.055 joules/mm<sup>2</sup>to the welding of 0.058 joule/mm<sup>2</sup>. </em></p>

scholarly journals Metal Oxide Nanoparticle-Based Coating as a Catalyzer for A-TIG Welding: Critical Raw Material Perspective

Metals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 567 ◽  
Author(s):  
Sebastian Balos ◽  
Miroslav Dramicanin ◽  
Petar Janjatovic ◽  
Ivan Zabunov ◽  
Damjan Klobcar ◽  
...  
Keyword(s):  
Weld Metal ◽  
Raw Materials ◽  
Metal Flow ◽  
Welding Process ◽  
Tig Welding ◽  
Raw Material ◽  
Oxide Coatings ◽  
Metallographic Examination ◽  
Metal Oxide Nanoparticle ◽  
Novel Approach

Besides a wide application in corrosion protection, wear resistance increase, providing thermal properties and power conversion, oxide coatings have found an alternative application in welding technology as catalysts of the tungsten inert gas (TIG) welding process. In this paper, the novel approach of fabricating a coating containing nanoparticles based on nanosized SiO2 and TiO2 and their mixtures was applied to the austenitic stainless-steel base metal. It was found that coatings increased depths of penetration, enabling a consumable-free welding. Using this method, the use of several critical and near-critical raw materials (e.g., Si and Cr), as well as the relatively expensive Ni can be completely avoided. The most effective coating in terms of weld penetration consisted of a mixture of nanoparticles, rather than unary oxide coatings based on nanoparticles. A model for liquid weld metal flow is proposed based on the metallographic examination of recrystallized grains and microhardnesses measured near the weld metal, supporting the reversed Marangoni convection theory.

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