Effects of Q&P process parameters on properties of 42SiCr steel – POSTER

Rubešová Kateřina - ZČU v Plzni (Czech Republic)

The requirement for high strength and good ductility poses problems in today’s advanced steels.
This problem can be tackled by appropriate heat treatment which produces suitable microstructures.
By this means, ultimate strengths of about 2000 MPa and elongations of more than 10% can be obtained. One of such advanced heat treatment techniques is the Q&P (Quenching and Partitioning) process. It produces a mixture of martensite and retained austenite, where the latter is an important agent in raising the ductility of steel.
In this experiment, a low-alloy steel with 0.43% carbon and manganese, silicon and chromium was used. An air furnace and a salt bath were employed for heat treatment and quenching, respectively.
In order to obtain the best ultimate strength and elongation levels, partitioning temperatures of 250°C and 300°C were applied. Partitioning involves carbon diffusion from super-saturated martensite into retained austenite, and tempering of hardening microstructure. Effects of the quenching temperatures of 200°C and 150°C were studied as well. To map the impact of the Q&P process on mechanical properties, an additional schedule with conventional quenching and tempering was carried out. Upon optimization of the parameters, the process produced martensite with a small amount of bainite and retained austenite. The ultimate strength was between 1930 and 2080 MPa and the elongation levels were from 9 to 16%.

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