THE BEHAVIOUR OF BORON-CONTAINING PHASE PRECIPITATION DURING HEATING IN 40MnB STEEL

The changes during reheating of the supersaturated solution boron in the40MnB steel previously formed by rapid cooling from elevated temperature weredetected by phase analysis and observed by track microphotography(boron autora-diography)and metallography.It was found that the boron-containing phases areprecipitated during heating from supersaturated solution boron as another differ-ent way of precipitation in comparison with that on cooling.X-ray diffractionshows that the major boron-containing phase is Fe_3(C,B),The correlationbetween its amount,size,precipitating rate,sites and heating temperature wasstudied.The similarities and differences as well as the connection each otherbetween these two precipitation ways were also discussed.