ANALISIS VARIASI SUHU PREHEAT PADA SAMBUNGAN LAS GTAW MATERIAL CuDHP TERHADAP NILAI KEKERASAN DAN STRUKTUR MIKRO

Abstract

In the manufacture of heat exchangers, condensers have parts made of CuDHP copper
material. One of the welding methods uses the GTAW (Gas Tungsten Arc Welding) welding process to
connect the CuDHP material. CuDHP. This material is a copper material that has high electrical and
thermal conductivity, which affects the weldability of the material. Thermal conductivity is the ability
of a material to conduct heat. heat. The short heat conductivity of the welding process causes low
heat input to the base metal. This can cause defects in the weld result. The short heat conductivity
process can be avoided by preheat before joining the materials. However, after the preheat and
welding process on the product, the welding results are still found defects, namely hot crack. This
defect is caused by the less than optimal preheat temperature that is carried out on the material
before it is welded. The temperature values varied are 150oC, 200oC, 250oC, 500oC. The tests carried
out were hardness and metallographic tests. The results of this study indicate that no crack was
found. There are several new phases in the fusion line area that have globular and unbranch dendrite
copper phospide precipitation. The highest hardness value is in the base metal spesimen150 °C
preheat variation of 56 kgf / mm 2 and the hardness value The lowest hardness value is at the base
metal of the 500 °C preheat variation spesimenof 34.3 kgf/mm. The deepest penetration of the preheat
variation with a temperature of 500 °C has the greatest depth of penetration. penetration and the
preheat variation with a temperature of 150 °C has the lowest penetration depth. the lowest
penetration depth.