EFFORTS OF ACHIEVING ARMOR STEEL QU ALIFICATION IN 4K3014AM AND 4K3014BM STEEL THROUGH QUENCHING AND TEMPERING HEAT TREATMENT WITH TEMPERING TEMPERATURE AND HOLDING TIME VARIATION

• Main Author: ILHAM - Nim: 12514020 , MUHAMMAD
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/29246
• Institution: Institut Teknologi Bandung

<p align="justify">One of the efforts to maintain Indonesian sovereignty from internal or external threats is the main weapon system (defense equipment). Indonesia already has a strategic industry in the field of defense equipment and steel manufacturing, namely PT. Pindad and PT. Krakatau Steel. But the raw material for the manufacture of defense equipment provided by PT. Pindad is still imported. PT Krakatau Steel has been able to make armor steel for defense equipment, namely KSW 500 which has been developed into 4K3014AM and 4K3014BM series, but further development is still needed. High hardness and toughness are the main mechanical properties requested by armored steel. Good hardness and toughness can be produced through hard and tough phases, such as tempered-martensite. In this study introducing tempering temperature and holding time on steel 4K3014AM (A) and 4K3014BM (B) were studied, then the results of the study will be compared with the standards and qualifications of steel armored. <br /> <br /> <br /> The heat treatment carried out in this study was quenching and tempering with the number of tempering temperatures of 200 oC, 300 oC, and 400 oC, as well as tempering holding time of 15 minutes, 30 minutes, and 45 minutes. The austenization process was carried out at 825 oC for 20 minutes followed by quenching using water media on an aluminum container. Tests carried out included trials, impact tests, tensile tests, metallographic observations and fault morphology observations using SEM. <br /> <br /> <br /> The results showed that the increasing temperature and tempering holding time, hardness, yield strength, and UTS would decrease while the size of prior-austeninte grain would increase even though it was not significant. In this study, the occurrence of tempered martensite embrittlement (TME) observed at tempering temperatures above 300 oC with a holding time above 30 minutes which caused the toughness to decrease with tempering temperature, consequently changes in elongation of the research variables could not be observed properly. The values of hardness, yield strength, and UTS were obtained through 200 oC tempering treatment for 15 minutes, which were 531,9 HB; 1703,04 MPa; 1875,02 MPa for steel A and 519.8 HB; 1767.97 MPa; 2021.13 MPa for steel B. The highest toughness value is obtained through 200 oC tempering treatment for 30 minutes which is 24,48 J for steel A and 22,58 J for steel B Comparison of experimental results with the armor-steel MIL-DTL-46100E standard and qualification shows that steel A and steel B meet minimum standards of hardness, but their toughness cannot be compared to standard due to differences in test conditions.<p align="justify"> <br />