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THE EFFECT OF TEMPERING PROCESS ON MECHANICAL PROPERTIES OF P460 STEELS JOINED BY SUBMERGED ARC WELDING Mustafa Turkmen1, *UgurCaligulu2, HalukKejanlı3,Tansel Tunçay4 1
KocaeliUniversity, Hereke Vocational School, Metallurgy Department,41800 Kocaeli FiratUniversity, Technology Faculty, Metallurgy and Materials Eng. Depart., 23119 Elazig 3 Dicle University, Engineering-Architecture Faculty, Mechanical Eng. Depart. 21000 Diyarbakir 4 Karabuk University, Technology Faculty, Manufacturing Eng. Depart., 78100 Karabük 2
[email protected],
[email protected],
[email protected],
[email protected] Abstract: In this study, P460 steels joined by using submerged arc welding method under different parameters (welding speed and current values). Tempering process was performed to welded joints at 300 0C, 400 0C and 500 0C for 1 hour. Welded joints were characterized in terms of hardness and charpy impact test before and after tempering. As a result of the experiments, it has been found that the P460 materials show the ability to weld sufficiently strong by the submerged welding method. In addition to, the results indicated that P460 welded joints showed the lower hardness values after tempering whereas the increase in impact toughness. Keywords:P460 Steel, Submerged Arc Welding, Tempering, Notch Impact Test, Microhardness.
TOZALTI ARK KAYNAĞI İLE BİRLEŞTİRİLEN P460 ÇELİKLERİN MEKANİK ÖZELLİKLERİNE TEMPERLEME İŞLEMİNİN ETKİSİ Özet: Bu çalışmada, P460 çelik malzemeler tozaltı kaynak yöntemi ile farklı kaynak parametreleri (kaynak hızı ve akım değeri) kullanılarak birleştirilmiştir. Birleştirilen numuneler 300 0C, 400 0C ve 500 0C sıcaklıklarda 1 saat süre ile temperlenmiştir. Ardından, kaynaklı birleştirilen numunelere temperleme öncesi ve sonrası olmak üzere sertlik ve darbe çentik testleri uygulanmıştır. Yapılan deneyler sonucunda, P460 malzemeler tozaltı kaynak yöntemiyle yeterince güçlü bir kaynak edilebilme yeteneği göstermiştir. Ayrıca, P460 çelik malzeme kullanılarak yapılan kaynaklı bağlantıların temperleme sonrası daha düşük sertlik buna karşın darbe tokluğunda artış gösterdiği tespit edilmiştir. Anahtar Kelimeler: P460 Çelik, Tozaltı kaynağı, Temperleme, Çentik darbe testi, Mikrosertlik. *Corresponding Author: UgurCaligulu.
[email protected]; Phone: (424) 23700 00 / 4225
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vessels closed to the atmosphere made by joining spherical, cylindrical or conical shaped volumes used in the production, transportation or storage industrial gases (air, oxygen, nitrogen, argon, hydrogen gas) in 0.490.105, Pa 0,5 ato and higher pressure, fuel gases (natural gas, acetylene gas, desulphurized coke gas) and steam. P460 steel material is mainly used in the manufacture of bridges, tankers, pipe fittings, and pressure vessels (CO2and LPG tanks etc.) [4-5]. In the submerged arc welding, arc also automatically occurs between the bare electrode and the workpiece being applied to the weld zone and it continues its function under a powder stack spilled to the weld zone from a separate canal. Since the welding arc is formed under powder stack, this method is called as submerged welding method [6]. Caliguluet al.,applied in oil cooling process after 1-hour annealing at900°C to the 38MnVS6 microalloyed steel and 41CrMo4 steel materials.The steel
INTRODUCTION
The alloy design of quenched and tempered steels having a widespread use in today’s industry and the improvement of their performances in line with applied heat treatments are inevitable. Tempering heat process applied for further enhancement of mechanical properties of the martensitic/bainitic structures formed with rapid cooling after austenitization affects such performance contribution significantly [1].With the developing technology, the heat treatments applied to the steelshave become important in the enhancement of the mechanical and metallographic properties of the steels depending on their widespread usage. Heating and cooling of the material at the solidus temperature with appropriate sequence and time to obtain a certain state in terms of internal structure and properties is called as heat treatment [2-3].Pressure vessels are defined as
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materials cooled in the oil were tempered for 1 hour at300°C, 400°C,and 500°C and the effect of the tempering process on their microstructure and mechanical properties was investigated [7]. Baday et al., investigated the effects of microstructural differences obtained by applying an over-tempering heat treatment to a medium-carbon steel on cutting forces and surface roughness. For this purpose, a quenching process was applied to a group of AISI 1050 material after 15-minute austenitization treatment at 850 °C and then cementites were spheroidized in the ferrite matrix by extreme tempering at 600°C separately for 15, 60, and 180 minutes[8].Arslan et al., performed puncture experimental studies by processing stainless steel sheet (AISI 304) in punch machine with punches made of DIN 1.2080 and cold work tool steels, which were subjected to cryogenic process,tempered after cryogenic process and untreated,and examined the face wear behaviors forming on the punches. For this purpose, the cold work tool steel punch was subjected to deep cryogenic treatment at -145°C. Tempering was also performed after deep cryogenic process [9]. Keleştemuret al., produced a dual-phase steel from the low-carbon SAE1010 structural steel, the basic building material of the construction industry and examined the effect of tempering heat treatment on the force-elongation curve of this steel [10].Karabulut et al., joined the micro-alloyed steel materials via the submerged welding method using a 450 A welding current value. Tempering process was applied to the welded joint [11].Erden et al., performed three different welded joints by using general purpose structural steel and hardox hituf steel materials joined by using the submerged welding method [12]. Akay et al., joined the X60, X65 and X70 steels used in petroleum and natural gas lines via using submerged arc welding method using different wires (S1 and S2Mo) and powders (LN761 and P223). Visual and radiographic examination techniques among nondestructive methods are applied firstly to the welded joints in order to determine the surface and sub-surface defects and then, spectral analysis studies were then performed to determine wire-powder-base material compositions in the welded area. In order to determine the toughness properties of the welded joints, a notch impact test was performed. In addition, hardness and microstructure studies were also conducted on the samples [13]. In this study, P460 steel materials were joined by using submerged welding method. After the tempering process was applied to the welded joint, mechanical properties of the joints were examined. Hardness and impact notch tests were performed on the welded joints before and after the tempering and microstructure studies were conducted. 2.
In this study, P460 steel whose chemical analyses are present in Table 1 and mechanical properties are present in Table 2 was joined in the OERLIKON-Mz1250BF welding machinevia submerged welding method by considering welding speeds and ampere values given in Table 3. Table 1. Chemical compositions of experimental materials Materi als P460 Com. wire Com. powder
C
Si
0,2 0 0,1 2 0,1 0
0,6 0 0,1 0 0,4
M n 1,1 0 1,0 0 1,6 0
P
S
0,0 20
0,0 05
C r 0, 3
Cu
Ni
0,70
0,8 0
M o 0,1 0
-
-
-
