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对超高强度钢板进行热处理,模拟热浸镀锌和合金化镀锌工艺的热循环,并考察获得的力学性能和微观组织。研究用钢含有适量的碳(~0.2%)、锰(1.2%)和铬(0.4%),保证钢板在奥氏体化后在镀锌前的连续退火线上进行快速冷却时能够完全转变成马氏体。采用不同的钒含量(0~0.1%)和氮含量(0.002%~0.012%),研究这些微合金化元素对回火马氏体强度的影响。尤其与高氮相配合情况下,钒有助于抵抗回火效应,因此在镀锌后大部分原始强化贡献被保留下来,使得钢的抗拉强度超过1 000 MPa。使用铝或硅进行不同脱氧试验,发现在同一碳含量下两者具有相同的强度水平,但是Si镇静钢的弯曲性能明显优异。对退火钢板进行微观组织观察,但是钒产生有益作用的原因还未完全掌握。通过研究得出这样结论:钒微合金化对耐腐蚀超高强度钢板的开发而言是一种极具前景的途径。
The ultra-high strength steel is heat-treated to simulate the thermal cycling of hot-dip galvanized and alloying galvanized processes and the mechanical properties and microstructures obtained are investigated. The research steels contain adequate amounts of carbon (~ 0.2%), manganese (1.2%) and chromium (0.4%) to ensure complete conversion of the steel sheet to its maximum temperature Martensite. The effects of these micro-alloying elements on the strength of tempered martensite were investigated using different vanadium levels (0-0.1%) and nitrogen levels (0.002% -0.012%). In particular, with high nitrogen, vanadium contributes to the resistance to tempering and therefore most of the original reinforcing contribution after galvanizing has been retained, resulting in a tensile strength of the steel exceeding 1 000 MPa. Different deoxidation experiments using aluminum or silicon showed that both had the same level of strength at the same carbon content, but the bending properties of Si killed steel were significantly superior. The microstructure of the annealed steel sheet was observed but the reason why vanadium produced a beneficial effect was not fully understood. The conclusion drawn from the study is that vanadium microalloying is a promising approach to the development of corrosion-resistant and ultra-high strength steel.