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本文叙述和讨论了沸腾钢和铁静钢钢三中板机械性能的系统研究和初步生产试验的经过和结果. 在初步生产试验中,证明了控制加工温度、压下规程、冷却速度和进行低温回火可以提高钢三中板的机械性能和冷弯性能. 在系统的研究中,找出了钢三中板的机械性能和冷弯性能与其显微结构和晶粒度之间的关系,以及进一步了解了原始奥氏体晶粒度和冷却速度对於成品的显微结构和晶粒度的影响.如果原始奥氏体晶粒很大(1号或以上),则成品的晶粒也很粗大,且易生成魏氏组织,对降伏强度和冷弯性能都有不良的影响;反之,如果奥氏体晶粒细小(6号或更小),则易生成细小均匀和等轴的成品晶粒,提高了成品的机械性能和冷弯性能;在相变期间冷却速度过低便易生成带状组织,对各种机械性能和冷弯性能都有不良的影响. 在系统的研究中并着重研究了奥氏体晶粒度在热加工过程中所发生的变化.实验结果指出,钢三的奥氏体晶粒经过加工后发生细化,但随着保温时间的增加又重新长大.奥氏体晶粒细化的程度主要决定於未加工前的晶粒大小和加工量,长大的程度则主要决定於保温时间、加工量和温度.因此在多次重复的热加工过程中,各次的加工量对於细化奥氏体晶粒便有了积累作用.每次加工之间的间隔时间愈短,积累作用也就愈显著.如果在轧钢过程中,缩短了各道次之间的间隔时间。增加了压下率,並在停轧后使钢板迅速冷却到相变点,便可能得到转变前的细小的奥氏体晶粒.
This paper describes and discusses the mechanical properties of the three plates of steel and iron static steel, and the results of the preliminary production test.In the preliminary production tests, it was proved that the control of the processing temperature, the depressing schedule, the cooling rate and the low temperature Tempering can improve the mechanical properties and cold-bending properties of the steel plate.In the systematic study, the relationship between the mechanical properties and the cold-bending properties of the steel-plate and the microstructure and grain size was found out, and Further understanding of the original austenite grain size and cooling rate on the microstructure and grain size of the finished product if the original austenite grain size (No. 1 or above), the finished grain is also very Coarse, and easy to generate Wei’s tissue, have an adverse effect on the buckling strength and cold-bending properties; the other hand, if austenite grains are small (No. 6 or smaller), it is easy to produce fine uniform and equiaxed finished products The mechanical properties and the cold bending properties of the finished product are improved, and the ribbon structure is easily formed when the cooling rate is too low during the phase transition, which has adverse effects on various mechanical properties and cold bending properties. In the research of the system, emphasis is also put on The austenite grain size was studied in hot addition The results show that the austenite grains of steel 3 are refined after processing, but re-grow with the increase of holding time.The degree of austenite grain refinement mainly determines Before the unprocessed grain size and processing volume, the degree of growth depends mainly on the holding time, processing capacity and temperature.Therefore in many repeated thermal processing, the amount of processing for the refinement of the austenite The accumulation of bulk grains has a cumulative effect, and the shorter the interval between treatments, the more significant the accumulation is and if there is a reduction in the time between passes during the rolling process. Increasing the reduction rate and cooling the steel plate to the transformation point quickly after stop-rolling, it is possible to obtain the small austenite grains before transformation.