快速冷却对DP1000双相钢激光焊接接头性能的影响

激光焊接DP1000双相先进高强钢的过程中，普遍存在焊接热影响区的软化现象，热影响区的软化严重影响了焊接结构的成形和使用性能. 为了能提高焊接接头的成形和使用性能，采用快速冷却的方式来改善其焊接热影响区的软化问题. 通过拉伸试验、显微硬度测试、扫描电镜和光学显微镜等手段对比研究了1.5 mm厚DP1000双相钢板有无快速冷却的焊接接头中组织和性能的变化. 结果表明，在快速冷却条件下，激光焊接DP1000双相钢的接头热影响区软化区较空冷焊接的窄，软化现象有所改善，强度和塑性均有所提高.

Effect of rapid cooling on mechanical properties of welded joint in laser welding of DP1000 dual phase steel

The softening phenomenon in heat affected zone existed in the laser welding processing of DP1000 dual phase high strength steel, which affected the formability and performance of welded structure seriously. In order to improve the formability and performance of welded joint, the way of rapid cooling was used to improve the softening in the heat affected zone of DP1000 dual phase steel laser welding. The microstructure and mechanical properties of welded joint of 1.5 mm thickness DP1000 steel plate with rapid cooling and air cooling were analyzed contrastively through the equipment of tensile tester, micro-hardness tester, scanning electron microscopy and optical microscopy. The results showed that softening zones in heat affected zone of welded joint was narrower under the condition of rapid cooling than under no rapid cooling during laser welding DP1000 dual phase steel. The softening phenomenon improved. The tensile strength and elongation were increased.