Original scientific paper
Effects of Steel Cast GS30Mn5 Hardening Parameters on Dredger`s Sheave Edge Properties
Dredgers are special sea floating vessels used for removing sea bottom material in order to: reshape harbor underwater areas and waterways, assembling pipelines, preparing sand beaches and coasts to handle with erosion impact, oil resources exploitation, forming man-made islands… This paper is based on selection of heat treatment parameters of sheaves, surface errors determination method and surface damages recovery. Om test samples made out of same material (GS30Mn5) built—up welding test was carried out of (SMAW procedure) by fluting prepared damage area. Next step was induction hardening using various parameters. Determination of cracks appearance was done by magnet method. By recording cross section structure as well as hardness measuring it has been determined that besides certain level of energy input (electrical current frequency) surface layer properties of sheave edge depend also about choosing proper cooling medium. Satisfying hardness values (320400 HB) were achieved combining air and water cooling simultaneously with avoiding cracks appearance. Parameters selected that way should ensure long working period of ropes (hardness 500550 HB) as well as safe dredgers performance.
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