硬线钢钒氮微合金化及控轧控冷工艺研究

【作者】 康卓；

【导师】 司云森； 马党参；

【作者基本信息】 昆明理工大学 ， 冶金物理化学， 2008， 硕士

【摘要】 我国线材市场对高性能线材产品的需求,使开发微合金化钢线材势在必行。本课题研究了钒氮微合金化对硬线钢组织和性能的影响。实验室条件下,对77B高碳硬线钢进行不同程度的V、N微合金化,使用Gleeble热模拟试验机以模拟高碳线材控轧控冷生产工艺,进行室温拉伸力学试验和金相组织观察,并利用Sisc-Ias金相图像分析仪分析金相组织中的索氏体的面积百分数,使用S-4300扫描电镜测量了珠光体的片层间距,用JEM-2000FX透射电镜观察了V(C,N)的析出形貌,最终探讨了钒氮微合金化硬线钢的强韧化机制,研究了钒氮微合金化对硬线钢组织和性能的影响。硬线钢钒氮微合金化后,采用合理的控轧控冷工艺,钢材的奥氏体晶粒细化,索氏体化率提高,珠光体片间距减小,试验材料的抗拉强度、硬度和韧性均得到了大幅度提高。例如:在相同工艺条件下,相比于普通硬线钢,含0.088%V,0.011%N钢的抗拉强度增长了60Mpa;断面收缩率增长了35%;热模拟试验结果表明,终轧温度为920℃,轧后冷却速度为15℃/S时,硬线钢的强度和韧性匹配最好研究认为钒氮微合金化硬线钢主要通过细晶强化和沉淀析出强化,从而提高钢材的强韧性。更多还原

【Abstract】 The demand of high performance wire rods makes micro-alloying wire rods’ exploitation necessary in our country. In this paper, influences of V-N micro-alloying on hard wire rods’ structure properties were researched.High-carbon steel wire rods 77B with different V-N content were made in the laboratory. The process of producing high-carbon steel wire rods controlled rolling and cooling was simulated by the Gleeble thermal simulating machine. Tension experiment in room-temperature was done, and microstructure was observed. The area percent of sorbite of test sample was analyzed by the Sisc-Ias metallurgical photos analysis machine. The interlamellar spacing of pearlite was measured by the S-4300 scanning electron microscopy. The precipitation of nitride and carbide was observed by the JEM-2000FX transmission electron microscopy. At last, the strengthen-toughening mechanism if a V-N micro-alloy hard wire rod was discussed, and influences of V-N micro-alloying on microstructure and properties of hard wire rods was researched.When the different content vanadium and nitrogen added in, austenite grain of wire rods refines, sorbite ratio rises and interlamllar spacing of pearlite reduce. Therefore, tensile strength, hardness and toughness of test samples are increased a lot. Such as, under the same process conditions compared to normal hard wire rods, tensile strength rises 60Mpa for wire rods with 0.088%Vand 0.011%N, its reduction of area rises 35%.The result of the thermal simulating experiment shows that if the roll-finishing temperature is 920℃and the cooling velocity after rolling is 15℃/S, the hardness and toughness of the hard wire rods will match each other best.It is considered that the V-N micro-alloyed high carbon wire rods obtain the high strength and toughness mainly due to grain refining and precipitation strengthening.更多还原