Technological Optimization of B-pillar Reinforced Panel Manufactured by a Press-hardening Steel Exceeding 1800 MPa

To validate the manufacturing feasibility of a novel Press Hardening Steel (PHS 1800), the B pillar reinforced panel was trail-produced by hot forming at temperature of 875 °C and 900°C. Besides, resistance spot welding was also carried out at welding current of 6-10 kA. Microstructure and mechanical properties of the B-pillar were examined using tensile test and scanning electron microscope (SEM). The results showed that the sample after hot formed at 900 °C exhibited the better mechanical properties, the tensile strength exceeded 1800 MPa; meanwhile, the elongation reached up to 8.6% which is comparative to conventional 1500 MPa counterparts. Under the fixed electron pressure and duration, the optimal welding current was determined to be 8.0-9.0 kA.