The purpose of this experiment is to find the effects on structures and cementite of rapid induced heating and tempering. The author designed a travelling magnetic field device, using a frequency conversion power supplier, the well prepared SS400 plates were heated, and some parameters are investigated through changing their values (frequency, current, gap from the pole surface to the steel plate and heating time). The temperatures during the heating process are recorded continuously. Meanwhile, the structures and hardness are investigated. The results show that the heating temperature affected the structure and the low temperature impact energy of the steel, at a suitable process parameters combining, the size and morphology of the separation and precipitation particles are very fine and distributed uniformity inside grains.

The aim of the determination is to study formation of precipitations by rapid tempering using thermal simulation tester and effects of precipitations on lower-temperature toughness property. A ultra low carbon microalloyed quenched steel containing alloying elements, such as 0.06wt%C-0.04wt%Nb-0.06wt%V-0.008wt%Ti, is tempered at 620°C for holding time 70min in conventional resistance furnace , and tempered rapidly at 620°C for 40s、80s and 120s, respectively. Both microstructures and impact properties were also investigated. It was observed that the nanoscale cementite particles were obtained by rapid tempering for 40s. Furthemore, the Charpy impcat energy of these specimens holding time 40s is higher than that of others. In comparison with conventionally processed, rapid tempering for low carbon alloyed steel can achieve good toughness due to the nanoscale cementite particles and offer the potential advantage for significant time and cost savings.