基体组织和过时效温度对冷轧连续退火dp钢组织性能的影响研究.doc

基体组织和过时效温度对冷轧连续退火 DP 钢组织性能的影响研究摘要: 针对三种不同的初始基体组织( F+P ,B,M), 利用电阻炉和盐浴炉模拟连续退火工艺, 研究了基体组织和过时效温度对冷轧连续退火 DP 钢组织性能的影响。结果表明, 经连续退火工艺处理, B和M 基体得到细小的呈纤维状分布的第二相,而 F+P 基体得到呈网状分布的尺寸粗大的第二相;在 450 ℃-250 ℃过时效时, 随过时效温度降低, 第二相组织由贝氏体向马氏体过渡; 在 250 ℃过时效, B和M 基体塑性好于 F+P 基体,这可归因于纤维状的形貌使基体与第二相在变形过程中界面结合力更强, 推迟了孔洞的过早形成。而在 350 ℃和 450 ℃过时效, B和M 基体塑性小于 F+P 基体,这可归因于碳化物在贝氏体和退火马氏体中分布更弥散,与基体较弱的结合力导致变形时孔洞形成的几率更大。关键词:基体,过时效温度,连续退火,双相钢,组织性能 Effect of Matrix and Overaging Temperature on Microstructures and Properties of Cool Rolled and Continuous Annealed DP Steel Abstract: The effect of different matrix (F+P, B and M) and overaging temperature on microstructures and properties of cool rolled and continuous annealed DP steel was investigated, by the aid of electrical resistance furnace and salt-bath furnace simulating continuous annealing process. The results show that B and M matrix attain fine and fiber second phase, while F+P matrix attain coa rse like second phase after continuous annealing process. Second phase is transited from bainite to martensite with reducing overaging temperature. O veraging at 250 ℃, p lasticity ofB and M matrix is superior to F+P matrix which attributes to the former owing bination of phase interface for re strain ing cavity forming during the deformation. But plasticity of the former is inferior to the latter when overaging at 350 ℃ and 450 ℃, which attribute to bination between brittle carbide and matrix, and more dispersed carbide leading to improve cavity forming probability in the former microstructure. Key words: matrix , overaging temperature, continuous annealing, dual phase steel, microstructure and property 前言 DP ( dual phase )钢是新一代高强钢,以其良好的强塑配合,较高的初始加工硬化速率,低的屈强比,而广泛应用于汽车领域[1-3] 。以往研究冷轧连续退火 DP 钢多是以冷轧态的铁素体加珠光体组织为基体进行,国外一些学者在研究 TRIP 效应辅助的 DP 钢时,提出以贝氏体或退火马氏体为基体得到的复相钢, 其塑性要更优[4-10] ,为解决 DP 钢在汽车某些成型性要求高的零件受限问题提供了可能性。为此,本文利用一种常用的 16Mn 钢成分,通过不同的热处理工艺条件,研究了不同基体组织和过时效温度对冷轧连续退火 DP 钢组织性能的影响。并与相关国外研究进行了对比。 1 实验方法 实验材料实验原料为某厂提供的 70mm 厚热轧板坯,表 1为实测的化学成分。表1 实验钢化学成分 Table 1