PENGARUH KECEPATAN TORCH DAN JENIS NYALA API TERHADAP KEKERASAN PERMUKAAN BAJA KARBON PADA PROSES AUTOMATIC FLAME SURFACE HARDENING

nugroho, Danang Septianto (2009) PENGARUH KECEPATAN TORCH DAN JENIS NYALA API TERHADAP KEKERASAN PERMUKAAN BAJA KARBON PADA PROSES AUTOMATIC FLAME SURFACE HARDENING. Other thesis, Universitas Sebelas Maret.

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Abstract

Surface hardening of metal is a method to enhance the surface hardness of a metal. The surface­ hardened metal possesses higher scale of hardness on the surface than in the core (the core remains ductile). The objective of the surface hardening in this research is to obtain the highest value of hardness of the carbon steel surface subjected to flame hardening. The output of this research could be applied to small scale industries of metal surface hardening to increase their product quality. This research utilized an automatic flame surface­hardening device. The surface hardening is performed by heating the specimen surface followed by quenching. The flame of oxy­asetylene is utilized to heating up the metal’s surface while the cooling is performed by water pumped from water reservoir. The speed and the flame of the torch are varied in this research. The speed of the torch and the cooling nozzle are regulated by inverter. The type of the flame is regulated through the oksigen and asetylene valves on the heating torch. The result of the testing shows that the best hardness value of the surface achieved when the torch speed is 28 mm/min and the type of the flame was carburation. The hardness of the surface of the specimen are 879,10 HV and 232,80 HV under the surface. Case depth on this specimen reaches 1,4mm from surface. The microstructure imaging shows the martensitic phase on the surface of the specimen while the middle and the bottom of the specimen shows the pearlit and the ferrite phase respectively. That’s why the specimen is hard on the surface while the core and the bottom of the specimen remain ductile. Keywords: flame hardening, hardening, carbon steel, quenching, martensit

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