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用超快速冷却技术并控制轧后冷却温度,研究了3种碳含量不同的碳素钢热轧后组织中渗碳体的析出行为和强化机制。结果表明,在超快速冷却条件下0.04%C和0.5%C(质量分数,下同)实验钢的主要强化方式分别是细化晶粒和细化珠光体片层间距,没有纳米级渗碳体颗粒析出,而在0.17%C实验钢的组织中则有大量弥散的纳米级渗碳体析出,颗粒直径范围为10-100 nm,通过超快速冷却技术实现了在不添加微合金元素的条件下纳米级渗碳体的析出。随着超快速冷却终冷温度的降低纳米渗碳体的析出强化作用使0.17%C钢的屈服强度提高110 MPa,强化效果明显。在超快速冷却的工艺基础上若继续采用形变热处理工艺,可进一步提高0.17%C实验钢的位错密度,促进渗碳体均匀形核,实现纳米级渗碳体颗粒在整个组织中更加均匀弥散的分布,达到更好的均匀强化效果。在超快速冷却和形变热处理工艺条件下0.17%C钢的屈服强度可达到650 MPa以上,强化效果提高300 MPa以上。
The supercritical cooling technique was used to control the post-rolling cooling temperature. The precipitation behavior and strengthening mechanism of cementite in three kinds of carbon steel with different carbon content after hot rolling were studied. The results show that the main strengthening methods of 0.04% C and 0.5% C (mass fraction, the same below) experimental steels are ultrafine grains and refined pearlite sheet spacing under ultra-fast cooling conditions, respectively, without nanometer scale cementite In the 0.17% C experimental steel, a large amount of dispersed nano-scale cementite was precipitated and the particle diameter ranged from 10 to 100 nm. The ultra-rapid cooling technique was adopted to achieve the microstructure of the steel without adding microalloying elements Nanometer cementite precipitation. With the ultra-rapid cooling of the final cooling temperature decreased nano-cementite precipitation strengthening effect of 0.17% C steel yield strength increased 110 MPa, the strengthening effect is obvious. On the basis of the ultra-rapid cooling process, if the deformation heat treatment process is continued, the dislocation density of 0.17% C experimental steel can be further increased, the uniform nucleation of cementite can be promoted, and the nano-sized cementite particles can be uniformly dispersed throughout the whole tissue The distribution, to achieve a better uniform enhancement. In ultra-rapid cooling and deformation heat treatment process conditions 0.17% C steel yield strength can reach more than 650 MPa, the strengthening effect of 300 MPa or more.