Hot Stamping of Boron Alloy Steels Using Resistance Heating

A hot stamping process of boron alloy steel using resistance heating was developed. Relationship between heating time and temperature was investigated. Hardness measurements and microstructural analyses of quenched blanks heated by resistance heating and furnace heating were performed. Miniature tensile specimens were machined from the quenched blanks and tested in tension at 0.01s stain rate. Temperature measurements showed that it only needed 1.4 seconds to heat the blank to 950°C using resistance heating. The resulting stress vs. strain curves showed that the UTS increased from 1496MPa to 1573MPa and the elongation increased from 10% to 16%for the specimens heated by resistance heating. In contrast to furnace heating, resistance heating produced more refined marensite grains and showed a little higher harness values. Keywords-hot stamping; boron steels; resistance heating; martensite;