THE EFFECT OF NIOBIUM MICROALLOYING ON PROCESSING AND APPLICATION PROPERTIES OF DUAL PHASE STEEL
Dual phase steel is widely used in today”s car body manufacturing.Its characteristics of high nvalue and good elongation(A80)are the basis of good press formability.However,practical experience has shown unexpected failure in forming operations where tight bending,stretch flanging or hole expansion are predominant.The inhomogeneous microstructure of soft ferrite and hard martensite in combination with highly localized straining is the origin of these problems.Furthermore,weldability and delayed cracking have been experienced to cause problems in ultra-high strength DP steel.Refinement and homogenization of the two-phase microstructure as well as lowering of the carbon content have been identified as remedies to the mentioned problems.However,mill processing of DP steel with reduced carbon content is more difficult especially for the higher strength levels.Niobium microalloying proved to be very effective in increasing the processing window of low-carbon DP steels besides of its natural effect of refining the microstructure.Meanwhile the production of niobium microalloyed DP steel has been established in several markets including China.The paper details the fundamentals,demonstrates respective production concepts and presents examples of application of Nb-microalloyed DP steels.
Dual phase steel bending hole expansion grain refinement process robustness
Hardy Mohrbacher NiobelCon bvba
Swaenebeecklaan 5,2970 Schilde,Belgium
国内会议
杭州
英文
605-611
2015-11-11（万方平台首次上网日期，不代表论文的发表时间）