Machining of Austenite Steels Using the Method of Preliminary Local Cryogenic Treatment

The oil and gas industry uses austenite stainless steels because of their high strength, flexibility, and resistance to the impacts of the atmosphere, damp environment, acids, salts, and other harsh chemicals. Problems in machining of such steels are associated with the formation of drain chip, their adhesion to the edge of the tool with the formation of build-up and the emergence of vibrations, which complicates the machining process and reduces its quality. The complexity of machining places greater demands on the tool used, the rigidity of technological equipment mandates the use of coolant, and various ways of chip removal. The scientific novelty consists in the fact that development of a method matches local cryogenic treatment with mechanical processing, ensuring automatic chip breaking and increased productivity. The influence of the method of cryogenic treatment on the structure, properties and machinability of austenitic steels was evaluated on the most common steel grade ۰۸Kh۱۸N۱۰T. The formation of a magnetic martensitic phase with increased hardness at the boundaries of austenitic grains, which causes a change in the mechanism and conditions of chip formation in the local zone, acts as a stress concentrator, resulting in drain chip segmentation and improved machinability. The main findings include an analysis of the method's impact on the dynamic stability of the mechanical processing technological system; reduction of surface roughness by ۲ times during mechanical processing with local cryogenic treatment compared to conventional cutting; ensuring stable segmentation and uniform fragmentation of the chip.

کلیدواژه ها:

machinability of austenitic steel ، Cryogenic treatment ، structural martensitic transformation ، hardening of surface layer ، chip segmentation ، auto oscillations