ABSTRAK
Tujuan penelitian ini adalah: (1) Mengetahui pengaruh temperatur quenching terhadap kekerasan pada pengelasan dissimilar welding baja tahan karat AISI 304 dengan baja karbon S45C; (2) Mengetahui pengaruh temperatur quenching terhadap kekuatan tarik pada pengelasan dissimilar welding baja tahan karat AISI 304 dengan baja karbon S45C; (3) Mendeskripsikan karakteristik mekanik hasil dissimilar welding baja tahan karat AISI 304 dengan baja karbon S45C dengan perlakuan variasi temperatur quenching yang berbeda.
Proses pengelasan dan pembuatan spesimen dilakukan di Laboratorium Las Inlastek Pajang Surakarta. Pengujian spesimen dilakukan di Laboratorium D3 Fakultas Teknik UGM. Jumlah spesimen dalam penelitian berjumlah 4 buah dengan rincian 3 spesimen mengalami perlakuan variasi temperatur quenching dan 1 spesimen tanpa perlakuan quenching. Teknik analisis data dalam penelitian ini adalah teknik analisis deskriptif kuantitatif. Pengambilan sampel pada penelitian ini menggunakan metode purposive sampling. Sampel yang digunakan dalam penelitian ini yaitu hasil pengelasan dissimilar welding baja tahan karat AISI 304 dengan baja karbon S45C menggunakan las GMAW.
Berdasarkan hasil penelitian dapat disimpulkan bahwa: (1) Terdapat pengaruh temperatur quenching terhadap kekerasan pada pengelasan dissimilar welding baja tahan karat AISI 304 dengan baja karbon S45C. Kekerasan pada setiap daerah memang berbeda-beda karena pada baja tahan karat AISI 304 kecenderungannya menurun disebabkan baja tahan karat tidak mampu keras, sedangkan untuk baja S45C rata-rata mengalami kenaikan mulai dari kekerasan tertinggi yaitu temperatur quenching air 5° C- 10° C, 25° C- 30° C, pendinginan udara dan 45° C- 50° C; (2) Terdapat pengaruh  temperatur quenching terhadap kekuatan tarik pada pengelasan dissimilar welding baja tahan karat AISI 304 dengan baja karbon S45C. Kekuatan tarik tertinggi terdapat pada spesimen dissimilar welding menggunakan pendinginan udara sebesar 575,696 Mpa, kemudian temperatur quenching air 25° C- 30° C  sebesar 521,053 Mpa, temperatur quenching air 5° C- 10° C sebesar 506,48 dan yang paling rendah temperatur quenching air 45° C- 50° C sebesar 406,853 Mpa; (3) Karakteristik mekanik hasil dissimilar welding baja tahan karat AISI 304 dengan baja karbon S45C dengan perlakuan variasi temperatur quenching yang berbeda menghasilkan nilai kekerasan yang paling tinggi dengan perlakuan temperatur quenching air 5° C- 10° C sebesar 538,35 VHN. Nilai kekuatan tarik yang paling tinggi terdapat pada pendinginan udara sebesar 575,696 Mpa. Keuletan didapat dari nilai regangan tertinggi yang terdapat pada pendinginan udara sebesar 12,66%, sehingga ketangguhan yang paling tinggi terdapat pada pendinginan udara.
Kata kunci: dissimilar welding, GMAW, temperatur quenching, baja tahan karat, karakteristik mekanik.
ABSTRACT
    The objectives of this study are: (1) In order to know the influence of quenching temperature towards the hardness in the welding of dissimilar welding at AISI 304 stainless steel and at S45C carbon steel. (2) In order to find out the impact of quenching temperature towards the tensile strength in the welding of dissimilar welding at AISI 304 stainless steel and at S45C carbon steel. (3) To discribe mechanical proprties in the result of dissmilar welding at AISI 304 stainless steel and at S45C carbon steel with the different  treatment quenching temperature variation.
The welding process and the specimen-making were conducted at Inlastek Welding Laboratory in Pajang Surakarta. The specimen-testing was conducted at D3 of Faculty of Engineering Laboratory in UGM. The total of the specimen in this study were four in which three specimen were conducted by using some varieties of quenching temperature and one specimen was not conducted by using any quenching temperatures. In this study, the data analysis technique used was descriptive quantitative. The sample which is used in this study is purposive sampling. The sample that is used in this study is the result of the dissimilar welding  at AISI 304 stainless steel and at S45C carbon steel  by using GMAW weld.
According to the result of this study, it could be concluded that: (1) There  was an influence of quenching temperature towards the hardness in the welding of dissimilar welding at AISI 304 stainless steel and at S45C carbon steel. However, the hardness in every area is different because the tendency at AISI 304 stainless steel is decreased caused of the stainless steel is not really strong, whereas in average at S45C , there is an ascension start from the highest hardness of the water quenching temperature in 5° C- 10° C, 25° C- 30° C, air cooling and in 45° C- 50° C; (2) There was an impact of quenching temperature towards the tensile strength in the welding of dissimilar welding at AISI 304 stainless steel and at S45C carbon steel.  The highest tensile strenght  is found in the specimen of the dissimilar welding which is used air cooling for about 575,696 Mpa, then the water quenching in temperature 25° C- 30° C  for about 521,053 Mpa, water quenching in temperature 5° C- 10° C for about 506,48 and the lowest temperature of water quenching at 45° C- 50° C for about 406,853 Mpa; (3) The result of mechanical properties of dissmilar welding at AISI 304 stainless steel and at S45C carbon steel with treatment quenching temperature variation that different have highest hardness number with water quenching  5° C- 10° C for about 538,35 VHN can. The result of highest tensile strength was identification in the air cooling for about 575,696. The result of ductile materials is identification in the air cooling that have highest  strain for abaout 12,66%, so the higheest  toughness is identification in the air cooling.
Keywords:    dissimilar welding, GMAW, quenching temperature, stainless steel, mechanical properties