Experimental Study On Fracture Toughness Of Cold Roll Material

With the development of modern industries, a large number of rollingtask have been caused by the tremendous production of steel. As a keycomponent of the rolling mill, the roll is a massive consumption. Therequirement in using condition of roll is becoming much more strict withthe market quality requirements for steel continuously rising and rollingtask for alloy steel and uneasy deformation metal growing. During thework process, the roll is undertaken a large quantity of rolling stress andunsteady heat leading to some failure forms such as fracture, peel and wear,etc. It is of necessity to do research on fracture toughness of rolls in orderto obtain the roll failure mechanism and life evaluation.This thesis mainly includes the following two parts:(1) Based on thetheory of failure, combined with fracture toughness test technology andCr5cold roll steel characteristics, KICis chosen as the test parameters andthe experiments on fracture toughness for Cr5cold roll steel are carried out.By using the three point bending specimens and the compact tensilespecimens, the fracture toughness for the surface of roll body and the rollneck, the fracture toughness along the radial depth in different parts of theroll and the fracture toughness influenced by sample geometry factors asside channel to the specimens are all been studied.(2) With thetemperature changing, the research on the fracture toughness for Cr5coldroll steel in different temperatures is achieved. With the fracture toughnessexperiments in environment temperature of353,323,293and273Kfinished, the KICvalue for Cr5steel with temperature changes arecalculated; the results show that fracture toughness of Cr5cold roll steeldecreases with the lower temperature; At the same time, the Cr5cold roll steel adaptation performance from the point of view on fracture toughnesswith changing temperature conditions is also discussed in this paper.