Pengaruh Suhu Preheat dan Variasi Arus pada Hasil Las Tig Aluminium Paduan terhadap Kekuatan Tarik dan Kekerasan

Aluminium has a good nature; corrosion-resistant, lightweight, and able to be recycled. But the connection with welding aluminum is difficult to do so we need the right way this study aims to determine the characteristics of the results of weld aluminum with large variations in preheat temperature and current. Aluminum Alloy AA 3003 TIG welded with Filler ER 5356, a variation current 110 A, 130 A, 140 A and preheat temperature of 75 degree celcius, 125 degree celcius, 175 degree celcius, then welds tested tensile, hardness, and microstructure. The results showed that the variation o f the current 110 A with a preheat temperature of 175 degree C has the highest tensile strength and hardness

Increased Knowledge of Pringwulung Youth Group, Sleman, on the Use of Solar Energy to Support Energy Security

The youth group RT10/ RW40 Pringwulung, Condong Catur, Depok, Sleman Yogyakarta Special Region is located east of SMKN 2 Depok, Sleman. This youth group formed a semi-autonomous activity centre under the youth organization which aims to provide knowledge to children in RT 10 about natural science. To implement the objectives, the workshop collaborated with several partners as resource persons for the activity. Some of the partners included lecturers and student associations around the location. The educational background of the youth groups varies from high school to tertiary education. The Adisutjipto College of Technology through its lecturers attempted to increase the knowledge of youth group members through a community-service partnership program on alternative energy, especially solar energy which has the potential to support energy security. It is hoped that through this activity the youth groups would be able to increase their knowledge. This community-service activity used the presentation method and to check the knowledge of youth group members, tests or questions and answers were provided with both at the beginning of the activity and the end of the activity. In addition, a small group discussion (SGD) was also conducted so that the participants could discuss the presentation material and improve the understanding of the material. In this community service activity, there was an increase in participants' knowledge, and indicators of improvement were shown from the results of the small group discussion, pre-test, and post-test sessions. The average percentage of increase of their knowledge from the pre-test and posttest results was 36%

PENGARUH DEFORMASI DINGIN DAN SURFACE MECHANICAL ATTRITION TREATMENT (SMAT) TERHADAP KEKERASAN, STRUKTUR MIKRO, DAN KETAHANAN KOROSI BAJA TAHAN KARAT AISI 316L

AISI 316L stainless steel has been widely used for biomedical material implants that needs high corrosion resistance and strength. Some methods have been developed in order to obtain its high performances, such as cold deformation and SMAT. This research aims to study the effects of combined methods (cold deformation and SMAT) in microstructure, hardness, and corrosion resistance of AISI 316L stainless steel. The dimension of specimen used in this investigation is 15 mm X 15 mm X 3mm. The cold deformation has been done to reduce the thickness by 47% using hydraulic press machine and followed by SMAT process. In SMAT process, 250 ball mill and motor speed of 1400 rpm are used with variation in dimension of 3.18 mm, 3.97 mm, 4.76 mm, and 6.35 mm. Besides, there is variation in duration: 5, 10, and 15 minutes. The results showed that cold deformation can increase the hardness about 127% and decrease the corrosion rate about 37%. Then combination cold deformation and SMAT can improve the hardness up to 16% and increase corrosion rate up to 40%