Ballistic resistant materials are materials containing right combination of hardness, strength, and toughness. The quench process produces high hardness and tensile strength but decreases toughness. The hardening process has been performed using an induction machine and a tempering process on a medium carbon steel plate. This work aimed to determine and analyze the effect of deep cryogenic treatment (DCT) on steel plates that have been quenched tempered. This research utilized steel plates of 130 x 130 x 8 mm size which has been quenched and then immersed in liquid nitrogen at a temperature of -196°C for 1, 5, 10, and 20 days. The micro Vickers hardness test specimen, tensile test and charpy impact test were made to determine the effect of immersion time. The test results and analysis showed that DCT had the ability to change microstructure, improve the hardness, tensile strength, and impact toughness. Furthermore, the maximum hardness was obtained during the immersion treatment of 20 days, which was 449.45 VHN and 1107.53 MPa, respectively. However, the highest toughness was obtained during the immersion of 10 days, which was 1,001 J/mm2. In order to get the optimal combination of ballistic characters, further ballistic testing is needed, both in simulation using the finite element method and ballistic experiment test.
Friction welding is a solid-state welding process using heat generated through friction. Dissimilar materials can be joined properly with friction welding. This study is a continuation of the previous study and aimed to determine the interface structure occurred on stainless steel and carbon steel joints. Stainless steel 304 and mild carbon steel are joined with this method at 2000 rpm rotation for 15 seconds and forging time of 5 seconds with a pressure of 5 MPa. The results of a micro-observation using a scanning electron microscope show good bonding in the interface area. The carbon steel is more welded to the stainless steel in the periphery than in the center. The spectrum results of Energy Dispersive X-Ray of the interface show Fe, C and Cr elements content. This is what causes the strong welding bond.
Dalam proses pengelasan, bagian yang di las menerima panas setempat yang mengakibatkan pengembangan termal, sedangkan bagian yang dingin tidak mengalami perubahan sehingga dapat mengakibatkan ketidak seragaman regangan, hal ini juga berpengaruh terhadap perubahan struktur yang terkandung didalamnya. Maka dari itu pemelihan jenis elektroda serta media pendingin sangat berpengaruh terhadap kekuatan tarik benda dan juga perubahan kandungan struktur yang terjadi di dalamnya. Berdasarkan analisa yang dilakukan, untuk jenis elektroda E6013 NK dengan media pendingin berupa oli, udara, dan air laut, nilai kekuatan tarik tertinggi pada media pendinginan udara yaitu sebesar 57.016 kg/mm². Sedangkan untuk jenis elektroda E7018 LB, kekuatan tarik rata-rata tertinggi justru pada jenis pendinginan air laut yang mencapai nilai tegangan tarik hingga 55.228 kg/mm². Kandungan Hidrogen rendah sangat baik untuk mencegah deoksidasi pada saat pengelasan, karena baja yang memiliki kadar oksigen tinggi apabila tercampur pada saat proses pengelasan, maka tegangan tariknya akan menurun.Keyword : pengelasan, media pendingin, elektroda, tegangan tarik, struktur mikro
Steel that has been heat treatment using quenching is hard but brittle. Tempering was done to remove the agility caused by the residual stress. The objective of this paper writing is to know and analyze the effect of tempering temperature on the mechanic property of steel plate of the surface hardening result. Steel plate with thickness of 8 mm of surface hardening result quenched by oil media was tempered at temperature of 100, 200, 300 and 400°C. Simulation based on finite element method was conducted to know the ballistic resistance. Experiment result showed that heating through induction and quenching on oil resulted in surface hardening. Tempering treatment decreased the hardness but at low temperature, the tensile strength increases. The simulation result showed that quenching and tempering material at temperature of 100°C was more able to resist the ballistic rate compared to other various temperatures.
Ballistic limit is a speed limit where projectile with a certain shape, angle of attack and size is not able to perforate a target with certain properties and thickness. This paper aims is to determine and analyze the ballistic limit of commercial medium carbon steel plate which has been hardened by induction heating by using finite element based simulation. A plate with a thickness of 8 mm was shot by a deformable blunt projectile with a diameter of 20 mm, a length of 80 mm and a mass of 0.197 kg with an angle of attack of 90° against the plate. Simulation results show that projectile with a speed of 225 m s−1 is still able to penetrate the plate in the form of plugging. The plate can withstand the projectile rate at a maximum speed of 215 m−1. At this speed, the plate is damaged but the projectile does not penetrate. The plate still has ductility properties, as during the simulation there were deflection and bulge in the back side.
Енергопоглинаюча здатнiсть може бути використана для вимiрювання опору матерiалу балiстичному удару. Метою даної роботи є аналiз енергопоглинаючої пластини з гумовим покриттям за допомогою пострiлу деформованими снарядами. Дане дослiдження проведено з використанням чисельного моделювання на основi кiнцевого елемента, пiдтвердженого експериментальними результатами. Установка моделювання на сталевiй пластинi з рiзною твердiстю з додаванням товщини гуми виготовлена у виглядi балiстичної випробувальної панелi. Шари не були закрiпленi на заднiй пластинi. Пострiл в панель здiйснювався з використанням деформованої кулi калiбру 5,56×45 мм з вiдстанню 15 м вiд нормального кута атаки. Для моделювання використовувався алгоритм по методу кiнцевих елементiв з моделями еластопластичного матерiалу Джонсона-Кука i Мунi-Рiвлiн. Результати моделювання показують, що енергiя балiстичного удару, отримана i поглинена панеллю, значно зростає незабаром пiсля зiткнення до тих пiр, поки не досягне певного значення на однiй пластинi, де енергiя зменшиться завдяки успiшному проникненню снаряда в пластину. У той час як на шаруватiй пластинi, пiсля того, як снаряду вдалося проникнути в передню бiчну пластину, енергiя поглинання досягла максимального значення i не змiнилася, що призвело до того, що снаряд не змiг проникнути в наступний шар. Данi результати свiдчать про те, що додавання гуми з шаруватою структурою дозволяє поглинати енергiю балiстичного удару. Ключовi слова: поглинач енергiї, тверда пластина, м'яка пластина, балiстична шарувата пластина, гума, балiстичний удар, моделювання
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