ABSTRAK
Dengan meningkatnya kenaikan produksi dalam suatu industri pada umumnya akandiikuti penurunan kualitas suatu produk dimana akan meningkatkan claim dari customeryaitu kegagalan mekanik pada rear axle shaft yang patah pada bagian flange. Untuk itudilakukan pengujian agar diketahui akar penyebab kegagalan rear axle shaft truk model Xdan memberikan solusi klaim patah. Pengujian yang dilakukan mencakup pengamatanfracture surface secara makroskopik dan mikroskopik, pengujian mekanikal properti sepertiuji tarik, pengujian komposisi kimia, pengujian kekasaran permukaan , uji Vickers / ujikekerasan, dan perhitungan shear stress maximal. Dari pengamatan fracture surface tidakditemukan crack awal yang menyebakan kegagalan rear axle shaft, hasil untuk uji tarikmaterial didapat sult 843 (N/mm2) syield 588 (N/mm2) e = 16.30%, untuk pengujian komposisikimia bahan didapat hasil yaitu C (0.42-0.48), Si (0.15-0.35), S (0.03) max, P (0.03) max,Mn( 1.35-1.65), Ni( 0.25 max), Cr (0.35 max), Cu( 0.3 max), dari hasil perhitungan shearstress maximal memakai persamaan sehingga hasil yang didapat≥ sult 42.15 N/m2 pada Konsentrasi tegangan Kt 1,406 dannilai Torsi , pada pengujian kekasaran permukaan hasil yang didapat semua adadalam nilai standard yaitu 3.2 RZ, pada pengujian kekerasan didapat nilai kekerasan 610 HVdimana standard kekerasan adalah 620HV?800HV, Dari semua pengujian tidak ditemukanpenyebab kegagalan pada rear axle shaft kecuali pada nilai kekerasan sehingga disimpulkanpenyebab patah pada poros dikarenakan nilai kekerasan kurang sehingga dilakukanperubahan parameter untuk proses hardening

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ABSTRACT
Increasing volume production in an industry in general will be followed by decline in

quality product which enhance their customer's claim such a mechanical failure on Rear Axle

shaft which fracture at the flange. The examination was done in order to know the root cause

of the failure of the truck rear axle shafts X model and provide solutions fracture claims Tests

performed include observation of fracture surface in macroscopic and microscopic, testing of

mechanical properties such as tensile test, the testing of chemical composition, surface

roughness testing, test Vickers / hardness test, and calculation of maximum shear stress.

From the observation of fracture surface was not found crack that caused the initial failure of

rear axle shafts, the result for material tensile test sult obtained 843 (N/mm2) syield 588

(N/mm2) e = 16:30%, for testing the chemical composition of the material we got the result

that C ( 0:42 to 0:48), Si (0:15 to 0:35), S (0.03) max, P (0.03) max, Mn (1.35-1.65), Ni (0.25

max), Cr (0:35 max), Cu (0.3 max). Tests performed include testing fracture surface, which is

done by macroscopic and microscopic,the result can not find crack test results early,

mechanical property testing sult obtained 843 (N/mm2) syield 588 (N/mm2) e = 16:30%,

testing the chemical composition of materials obtained results as the standard C (0:42 to

0:48), Si (0:15 to 0:35), S (0.03) max, P (0.03) max, Mn (1.35-1.65), Ni (0.25 max), Cr (0:35

max), Cu (0.3 max), the results of calculations based on the simulated shear stress values

from the equation that is ≥ Sult 42.15 N/m2

obtained maximal torque in the shaft, with a value of 1.406 Kt stress concentration results,

value of hardness testing got result 610 HV hardness but the standard 620HV-800HV, thus

found to be less than the standard. From testing concluded the cause of shaft fractures due to

the lack of hardness, so that changes the process of hardening parameters.