Abstract: The simulation test on controlling rolling and cooling process for Φ28 mm round billet of cold heading steel 10B21 (/% : 0. 20C, 0. 20Si, 0. 85Mn, 0. 014P, 0.005S, 0. 001 8B) to be going to finishing rolling has been carried out by using Gleeble-1500 thermal simulation machine to study the effect of finishing rolling temperature- 850 ~ 1 000 °C with deformation rate 20 s ^-1 and reduction- 65% , loop-laying temperature 820 〜940 ℃ and cooling rate in phase transformation range- 0. 2 〜1.0 °C/s on structure of steel. Results show that with increasing loop-laying temperature and cooling rate in phase transformation range the volume fraction of ferrite in steel increases obviously and with increasing cooling rate in phase transformation range the banded structure of steel is improved availably. In order to get higher ferrite volume fraction, coarser ferrite grain and more homogeneous structure to increase the cold heading performance, the optimum controlling rolling and cooling process parameters are finishing temperature- 950°C, loop-laying temperature- 910°C and cooling rate in phase transformation range- 1. 0 °C/s.

摘要： 通过Gleeble-1500热模拟实验机对冷镦钢10B21(/%:0.20C,0.02Si,0.85Mn,0.014P,0.005S,0.001 8B)精轧前Φ28 mm圆坯进行控轧控冷工艺热模拟试验,以研究变形速率20 s^-1,变形量65%时终轧温度(850~1 000℃) 、吐丝温度(820~940℃)和相变区冷却速度(0.2~1.0℃/s)对该钢组织的影响。结果表明,增加吐丝温度和相变区冷却速度可明显提高钢中铁素体含量,增加相变区冷却速度,可有效地改善钢的带状组织。为了获得较高的铁素体含量、粗大的铁素体晶粒且较均匀的组织,以提高钢的冷镦性能,较佳的控轧控冷工艺为终轧温度950℃、吐丝温度910℃、相变区冷却速度1.0℃/s。