In this work, the authors employ computer modeling to investigate a quenching process recently demonstrated at Karlsruhe Institute of Technology. A matrix of models was run to assess the effects of heat transfer and phase transformation kinetics on residual stress and microstructure in a relatively thick walled tube. The experiments at Karlsruhe were conducted using a high pressure water quench to produce martensite and residual compressive stress in the bore of a 4140 steel tube. Results show that the timing and rate of martensite formation and bainite kinetics have a significant effect on both the in-process and residual stress state.

Flash Bainite Processing employs rapid thermal cycling (<10s) to strengthen commercial off the shelf (COTS) steel sheet, plate, and tubing into advanced high strength steel (AHSS). In a continuous process, induction technology heats a narrow segment of the steel cross section in just seconds to atypically high temperatures (1000-1300°C). Quenching substantially immediately follows. Flash Processing optimizes the inherent heterogeneity of steelmaking to form a complex intra-granular multi-chemistry, mixture of bainite, martensite, and other morphologies. Carbon migration and carbide dissolution are controlled by limiting time in the austenitic range. Unlike conventional heat treating, homogeneity is intentionally avoided. Flashing steel such as AISI1010 (1100MPa UTS), AISI1020 (1500MPa UTS), AISI1330 (1800MPa UTS), and 13Cr (1800MPa) has shown excellent room temperature stampability. Flash 1500 has room temp stamped into complex shapes including B-pillars and automotive seat components. Flash 1800 has shown <2T bends in complex geometry from 1 to 2mm thick 400x2000mm sheets.

Martensitic steels must be tempered to increase their toughness and ductility. The tempering process requires heating from room temperature to the desired tempering temperature. In this paper, the effects of heating rates on carbide precipitate size distribution, chemistry, and precipitate density will be discussed. As-quenched martensite in AISI 4140 steel was heated to selected tempering temperatures in air furnaces as well as by induction. The heating rates for tempering vary from 30 seconds to 20 minutes. The experimental results are presented, and carbides were characterized using an extraction technique.

The present work is the first stage of an ongoing research project concerning with integration of quenching and partitioning heat treatment into the traditional hot stamping process, for 22MnB5 alloy, high Si and high Mn steels, last two proposed for the research with a special chemical composition to enhance Quenching and partitioning (Q&P) process. The above, in order to produce a microstructure containing retained austenite and martensite to improve the ductility of resultant components. The investigations of quenching and partitioning process were made by means of dilatometry and hot stamping plus quenching and partitioning (HS - Q&P) process experiments by a special experimental tool. The resulting microstructure was examined using light optical and scanning electron microscope as X-ray diffraction too. Some results obtained shown that compared with conventional hot stamping samples, the HS-Q&P process improves elongation effectively and maintains high-strength at the same time.