Thermo-Mechanic Treatment Case Study

Abstract Thermo-mechanic treatment consists in utilization of two classic technological proceedings. This type of treatment was applied to the studied high-speed steel (HS2-9-1-8). The made tests wanted to establish the influence on the hardness and wear of the high-temperature thermo-mechanical treatment (HTTMT) applied to studied steel. The application of an additional plastic deformation (the deformation degree between 45 – 75%) influences positive the hardness and wear value. Being a HTTMT, the plastic deformation was fallowed by quenching, the utilized agent being the oil or compressed air. When the quenching agent was the oil, the hardness increased with 6-7% and the wear diminished up to 40%. As the comparison elements were used the …show more content…
The figure 1 shows a comparison between the HS2-9-1-8 high-speed steel microstructures for different plastic deformation degree (nital attack reagent, 100 x enlargement). The sample deformed with =70% has the best microstructure because the constituents repartition is uniform; structure is very fine and, probably, the best mechanical properties.
The thermo-mechanic treatment continued with an oil quenching (oil temperature 100oC), has maintained the positive evolution of the microstructure (Murakami attack reagent, 400 x enlargement). For =70% is observed the carbides with small dimensions (dark colour area) and their uniform distribution. The =70% microstructure is better than =60% and obvious than =0% (see figure 2).
3. Experimental results
The tests were made on cylindrical samples of HS2-9-1-8 high-speed steel with the initial diameter of 25 mm and the initial height of 40 mm. These were pressed through forging with various deformation degrees. The deformation degree was calculated with (1). Applying HTTMT determines significantly improving of the HS2-9-1-8 high-speed steel micro-structure in comparison with the samples that not having benefited of plastic deformation. For the thermo-mechanically treated samples and, oil or air quenched, the hardness was

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