Study of residual casting stresses in cast iron rolling rolls

Abstract

The metal magnetic memory method (MMM) is a fundamentally new direction in technical diagnostics. It is the passive method that uses information emitted by a product or structure. In addition to early detection of a developing defect, the MMM provides information about the actual stress-strain state of the test object. When diagnosing equipment using the metal magnetic memory, the main criterion for stress concentration zones is the presence in this zone of lines characterized by a change in the sign of the normal component of the intrinsic stray field. Studies have shown that storing the rolls during 22 days significantly reduces the residual stress level. An increase in the duration of the roll storing contributes to a greater reduction in stresses in castings. The studies have shown that the MMM method application made it possible to assess the unevenness of the stress-strain state of the rolls and to identify the stress concentration zones - the sources of cracking. Storing the rolls after casting leads to a significant reduction in the level of residual stresses. Rough machining results in the appearance of zones with an increased level of residual stresses, which can initiate the formation of cracks in rolls during their operation. The use of the MMM method will enable to develop a technology for accelerated stress relief in castings of rolls after their machining, eliminating aging.