Original scientific paper
EFFECTS OF CONCENTRATION WATERMISCIBLE METALWORKING FLUIDS ON COOLING RATE
Ljiljana Pedišić
; Maziva-Zagreb d.o.o.
Božidar Matijević
; Faculty of Mechanical Engineering and Naval Architecture
Jasminka Munić
; Maziva-Zagreb d.o.o.
Abstract
Quenching is the most common procedure of metal heat treatment, which involves adequate cooling from given austenite temperature to achieve full transformation into martenzite structure. The cooling rate of quenching media mainly depends on thermal characteristics of the metals, section thickness of the workpieces, and the quenching medium heat-removal properties. Correct selection of adequate cooling media decreases risk of tension formation, possible cracking, and deformation of workpieces. The most commonly used cooling media for quenching steel are water, vegetable and mineral oils, polymer solutions, molten salts, fluidized baths, gases, and air. Water is a severe quenchant while oils cool more slowly than water but their main disadvantage is high fire hazard. Using watermiscible fluids combines positive properties of those two types of quenchant media, the water and the oils.
In this work are presented physical and chemical properties of watermiscible metalworking fluids as cooling media. Several fluid mixtures were prepared with water in different concentrations. Cooling curves for every concentration of test cooling fluids are plotted with determined cooling rates and H-values using ISO 9950 standard.
Keywords
emulsions for immersion hardening; martensitic quench hardening of steel; petroleum and related products of synthetic base; comparative evaluation viewpoint
Hrčak ID:
32674
URI
Publication date:
31.12.2008.
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