Study of Mechanical Properties of Carbon Steel Plate SA-516 Gr. 70 Welded by SAW Using V-Shape Joint Design

Amin, Sakib Bin; Hanna, Mohannad Y.

doi:10.30684/etj.v38i2a.269

Cited by 2 publications

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“…Nilai kekerasan hasil las dapat meningkat karena adanya nilai yang terlalu rendah dari kecepatan las dan heat input yang berlebih. Kemudian laju pendinginan yang tinggi juga menyebabkan hal yang sama (Amin, Hanna, dan Khider 2020). Tiga hal ini dimungkinan terjadi pada pengelasan pelat sebelum cold forming.…”

Section: Perhitungan Nilai Kemampulasanunclassified

“…Secara bersamaan persentase inklusi las mengurangi nilai elongasi jika fluks yang digunakan mengandung TiO2. Peningkatan kekuatan dan penurunan elongasi pada area terpengaruh panas juga disebabkan heat input yang berlebih (Amin, Hanna, dan Khider, 2020). Adapun laju pendinginan yang sangat tinggi dapat menurunkan ketangguhan karena mendukung pembentukan konstituen mikro keras seperti martensit dan bainit (Amanie, Oguocha, dan Yannacopoulos 2012).…”

Section: Perhitungan Nilai Kemampulasanunclassified

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Analisis Kegagalan Pembentukan Ellipsoidal Head Pressure Vessel dari Dua Pelat Dilas ASME SA516 Grade 70N dengan menggunakan Metode Fabrikasi Cold Forming

Suardi¹,

Fadli

2021

met. indonesia

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AbstrakHead pada pressure vessel yang berbentuk melengkung, seperti: hemispherical, torispherical, dan ellipsoidal dapat dibuat dari pelat dengan lebar 2.5 m yang mengalami proses metal forming. Namun, pelat yang tersedia di pasaran pada umumnya memiliki lebar 1,6 m. Kondisi ini menjadi batasan apabila ingin menggunakan satu material pelat secara integral sehingga dibutuhkan pelat untuk membuat head dengan lebar yang lebih besar. Oleh karena itu, untuk membuat head dengan lebar 2,5 m dilakukan proses cold forming pada dua pelat yang dilas. Namun setelah proses dilakukan, terjadi kegagalan berupa timbulnya retakan di sekitar area las. Pada paper ini akan dibahas analisis kegagalan proses cold forming yang terjadi pada dua pelat ASME SA516 grade 70N yang digunakan sebagai base metal. Untuk menganalisis penyebab kegagalan, maka dilakukan pengujian kekerasan, tarik, metalografi, dan komposisi kimia. Selain itu juga dilakukan perhitungan untuk mengetahui nilai crack consists of hot (UCS), cold cracking (Pcm), dan carbon equivalent (CE). Hasil perhitungan menunjukkan bahwa material tersebut memiliki nilai UCS di bawah 30, nilai Pcm berada di antara 0,23-0,35%, serta berada di zona II pada diagram Graville dimana nilai tersebut menunjukkan bahwa material memiliki kemampulasan yang baik. Sementara dari hasil pengujian mekanis didapatkan nilai kekerasan dan kekuatan tarik yang lebih besar dari standar, yaitu masing-masing sebesar 300 HBW dan 621 Mpa dengan nilai elongasi yang masih tinggi, yaitu sebesar 21,8%. Hasil pengamatan metalografi menunjukkan terbentuk fase martensit namun dalam jumlah yang sedikit pada area heat affected zone (HAZ) dengan bentuk butir seperti jarum. Fase martensit ini berperan sebagai stress concentration yang menjadi titik awal retak ketika proses cold forming dilakukan. Terbentuknya fasa martensit ini disebabkan oleh proses preheat yang tidak sesuai serta heat input yang terlalu besar. Abstract The head on a pressure vessel with curved shapes such as hemispherical, torispherical, and ellipsoidal is derived from the formed plate. Generally the plates available in the market have a width of 1.6 m, this condition becomes a limitation if you want to use one plate material integrally so that a plate is needed to make a head with a larger width. Therefore, to make a head with a width of 2.5 m, a cold forming process is carried out on two welded plates. However, after the process is carried out, failure occurs in the form of cracks around the weld area. In this paper, we will discuss the failure analysis of the cold forming process that occurred on two ASME SA516 grade 70N plates used as base metal. In order to analyze the causes of failure, hardness, tensile, metallographic, and chemical composition tests were carried out. In addition, calculations were also carried out to determine the value of crack consists of hot (UCS), cold cracking (Pcm), and carbon equivalent (CE). From the calculation results it is evident that the material has a UCS value below 30, the PCm value is between 0.23-0.35%, and is in zone II on the Graville diagram where this value indicates that the material has good weldability. Meanwhile, from the results of mechanical testing, the hardness and tensile strength values are greater than the standard, which are 300 HBW and 621 Mpa, respectively, with a high elongation value, which is 21.8%. The results of metallographic observations showed that the martensite phase was formed but in small amounts in the heat affected zone (HAZ) area with needle-like grain shapes. This martensite phase acts as a stress concentration which is the starting point for cracks when the cold forming process is carried out. The formation of the martensite phase is caused by an inappropriate preheat process and the heat input is too large.

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Section: Perhitungan Nilai Kemampulasanunclassified

Analisis Kegagalan Pembentukan Ellipsoidal Head Pressure Vessel dari Dua Pelat Dilas ASME SA516 Grade 70N dengan menggunakan Metode Fabrikasi Cold Forming

Suardi¹,

Fadli

2021

met. indonesia

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Development of parametric window and optimization of process parameters to predict bead profile in magnetically controlled gas tungsten arc welding

Shakya,

Singh,

Arya

2024

Proceedings of the Institution of Mechanical Engineers, Part E:

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A novel methodology has been proposed to tame the arc shape by adopting an external magnetic field, resulting weld profile as required. The co-axial magnetic field developed by specially designed electromagnets is superimposed on the welding arc. It was found that 0-0-S-N configuration provided more penetration than conventional gas tungsten arc welding. A parametric window has been developed for the selected configuration to obtain the desired bead geometry. The experiments were performed using process parameters as suggested by the design matrix, developed using response surface method technique. Mathematical models were evolved from experimental data for penetration and bead width. The evolved model for penetration is adequate up to 99.72% confidence level and for bead width is 99.98% confidence level. The effects of process parameters have been presented in a graphical manner for better understanding. The penetration achieved with the magnetically controlled GTAW process is 3.92 mm, which is 30% more than that achieved with conventional GTAW. The bead width increases initially, up to a certain limit, and then reduces with an increase in excitation current. Further, the experiments have been conducted on the optimized parameters for the validation of models. The refined grains were obtained due to magnetic stirring of the molten pool, which is desirable for improvement in mechanical properties of welds. The average grain size was reduced from 42.55 to 31.03 µm. The improved microstructure containing more amount of acicular ferrite was obtained with magnetically controlled arc.

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Study of Mechanical Properties of Carbon Steel Plate SA-516 Gr. 70 Welded by SAW Using V-Shape Joint Design

Cited by 2 publications

References 4 publications

Analisis Kegagalan Pembentukan Ellipsoidal Head Pressure Vessel dari Dua Pelat Dilas ASME SA516 Grade 70N dengan menggunakan Metode Fabrikasi Cold Forming

Analisis Kegagalan Pembentukan Ellipsoidal Head Pressure Vessel dari Dua Pelat Dilas ASME SA516 Grade 70N dengan menggunakan Metode Fabrikasi Cold Forming

Development of parametric window and optimization of process parameters to predict bead profile in magnetically controlled gas tungsten arc welding

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