Plasma arc surface modification of ASSAB 705 steel

Wagiman , Abdullah (2006) Plasma arc surface modification of ASSAB 705 steel. Masters thesis, Universiti Malaya.

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Abstract

Modification of steel surface by hardening process is traditionally done either by oxy-fuel, induction, laser or electron beam hardening. The technique using plasma arc which needed low initial cost is a new alternative for surface hardening. In this work, single and multiple pass of plasma arc was used to improve the hardness of ASSAB 705 steel surface. The variable parameters investigated were scanning velocity, operating current, gas pressure and stand off distance. After single pass scanning treatment, four types of surfaces were observed. They were fully-melted, partially-melted, non-melted and inconstant-affected where each type of surface indicated different type of roughness. This work has showed that scanning speed and operating current was significantly influence the type of surface and roughness values. Analysis on nonmelted surface after treatment gives maximum depth of hardened layer of about 186.7 um as well as hardness values of about 1100 HV50. It was also observed that the depth of harden layer and hardness value was significantly decreases with increase in scanning speed or with decreasing operating current. Microstructure analysis on hardened layer also revealed the formation of martensite structure. Single pass scanning treatment produced approximately 2 mm width of hardened surface. Larger area of hardened surface could be produced by multiple pass scanning treatment. However the treatment produced uneven hardness due to reheating effect on prior hardened layer. The results from this work indicate that plasma arc is viable tool for surface hardening.

Item Type:Thesis (Masters)
Subjects:T Technology > TK Electrical engineering. Electronics Nuclear engineering
ID Code:827
Deposited By:Ms Aryanti Ahmad
Deposited On:06 Apr 2011 10:13
Last Modified:29 Apr 2011 14:42

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