冷却速度对Φ13mm SWRH82B线材组织性能影响及控冷工艺优化实践

Effect of Cooling Rate on Structure and Properties of Φ13 mm SWRH82B Rod Coil and Optimized Practice of Controlled Cooling Process

采用热模拟试验机测定了SWRH82B钢（／％：0．80C，0．84Mn，0．22Si，0．013P，0．008S，0．32Cr）的相变点和连续冷却转变（CCT）曲线，通过金相显微镜、SEM、TEM及力学性能测试分析了冷却速度（1—25℃／s）对SWRH82B线材相变组织、珠光体片层间距和力学性能的影响，得到了最佳冷却速度为8—10℃／s；通过150mm×150mmSWRH82B钢铸坯轧成Ф13mm盘条后风冷4组Z1～Z13辊道速度（0．8—1．25m／s，1．0—1．45m／s，1．05—1．50m／s，1．10—1．55m／s）和冷却速度（8．9，9．5，10．4，11．2℃／s）进行了生产试验，得出在斯泰尔摩风冷线上的获得最佳冷却速度8～10℃／s首段辊道速度应为0．8～1．0m／s，可达到用户要求的指标：时效后抗拉强度≥1130MPa和断面收缩率≥30％，索氏体率≥80％，表面脱碳深度≤1．5％D（D-线材直径）。

The phase transformation point and continuous cooling transformation （CCT） curves of SWRH82B steel （/% ： 0. 80C, 0. 84Mn, 0. 22Si, 0. 013P, 0. 008S, 0. 32Cr） are measured by thermal simulation machine, and the effect of cooling rate （ 1 -25 ℃/s） on phase transformation structure, pearlite interlamellar spacing and mechanical properties of SWRH82B rod coil is analyzed by optical microscope, SEM, TEM and mechanical testing to get the optimum cooling rate 8 - 10 ℃/s. The commercial production test is carried out by 150 mm× 150 mm billet of SWRH82B steel rolled to Ф13 mm rod coil and fan cooling with four Z1-Z13 cooling roller speed （0. 8 - 1.25 m/s, 1.0 - 1.45 m/s, 1.05 - 1.50 m/s and 1.10 - 1.55 m/s） and cooling rate （8. 9, 9. 5, 10. 4 and 11.2 ℃/s） , and it is obtained that in order to get optimum cooling rate 8 - 10 ℃/s at Stelmor cooling line the roller speed of first section should be 0. 8 - 1.0 m/s to come up to the required index of user： aged tensile strength ≥1 130 MPa and reduction of area ≥30% , sorbitic structure ratio ≥80% and depth of surface decarburization ≤ 1.5 % D （ D- diameter of rod coil）.