The low-alloy round steel is processed by using the middle refrigeration process
1. Reduce the use of aluminum alloy
Before the investment in billet refrigeration, the average quality performance of Nb was 193.4×10-6, and after the capital investment, the average quality performance of Nb was 119.4×10-6, and the quality performance of Nb decreased by 74×10-6, while the compressive strength and plastic deformation were not affected. In addition, the original low-alloy round steel composition of XZ low-alloy round steel plant has Al element, which is used for cold-rolling low-alloy round steel with a thickness of 40~50 mm after selecting the middle refrigeration, the blank composition and the main parameters of the cold-rolling processing process are improved, and the slab of the low-alloy round steel composition without Al can be used to replace the production and manufacturing, with an average tensile strength of 355.60MPa, and the actual application effect is excellent.
2. Improving institutions
The middle refrigeration process can reasonably optimize the crystals. The indoor temperature mechanism of the 25mm thin thickness low-alloy round steel after the middle refrigeration processing technology is selected, and the surface mechanism and management center on both sides of the jaw plate are ferrite + ferrite, and the mechanism is fine, and the ferrite grain size grade at 1/4 of the thickness is 10.4~10.6; The ferrite grain size at 1/4 of the thickness of the low-alloy round steel manufactured by the basic manipulation cold rolling processing technology is 8.6~9.1 grade. In addition, according to the careful operation of the whole process of refrigeration of the middle billet refrigeration equipment, the symmetry of its different plate characteristics is also gradually improved.
3. Improve physical performance
The results of the comparison of the physical properties of the 16mm thick low-alloy round steel after the selection of intermediate refrigeration and basic air cooling show that the intermediate refrigeration can reasonably improve the impact work of the jaw, and the tensile strength can be increased by 15~30MPa, and the elongation has no significant effect. The key reason is that the middle refrigeration reasonably inhibits the growth of the work-NMened crystal, optimizes the martensitic crystal, and is beneficial to improve the ductility.
Fourth, improve productivity
Comparing the productivity of the middle refrigeration capital before and after the investment: when 7 pieces of cold rolling are selected, the waiting time of the middle billet can be reduced from the original 19min52s to 15min22s; For 79mm thick middle billets, the productivity of 46mm low-alloy round bars can be increased by 30.36% for each billet cold-rolled, and the productivity of several pieces of cold-rolled steel can be increased by 12.67%.