Water-crossing cooling system
QTB process (ribbed steel surface hardening and self-tempering)
|
The control principle of the process is shown in the figure. During the quenching phase, when the bar leaves the finishing mill, it needs to be vigorously water-cooled to form a chill layer on the surface of the bar, the cooling rate is higher than the martensite velocity to obtain coarse martensite; in the tempering phase, the heat is from the temperature The still high core of the bar is transferred to the quenched surface, so that the Martens obtained in the first stage is self-tempered; the third stage is on the cold bed, the core of the bar is unconverted austenite. Isothermal phase change. Since the tempered martensite structure is formed on the surface of the bar, the yield strength can be increased by about 100 MPa or more, which can replace the further processing which affects the toughness of the material. The product has high strength while ensuring sufficient toughness, and the product quality is better than that of hot-rolled and air-cooled microalloyed steel and low alloy steel. Moreover, due to the low carbon equivalent, the ribbed steel bar after the QTB process can also obtain better welding performance. In this process, the finish rolling temperature, quenching time, and water flow rate are key parameters of the quenching process, and the quenching process determines a specific tempering temperature, which determines the proportion of the tempered martensite ring area and The final determination of the mechanical properties of the product, especially the tensile properties. |
Second-line and four-wire water-cooling assembly |
|
|
|
QTB process (specification) 1. Bar material small size (φ10, φ12, φ14) after rolling water design, complete equipment manufacturing, installation, commissioning. (including paving equipment, pipeline layout construction, electronic control) 2. Large bar specifications (φ16, φ18, φ20, φ22, φ25, φ28, φ32, φ36, φ40) are designed for water-passing process, complete equipment manufacturing, installation and commissioning. (including paving equipment, pipeline layout construction, electronic control) |
|
|
QTB process target performance Rolling HRB335 by Q235 to meet the requirements of GB1499-1988 Rolling HRB400 by HRB335 to meet the requirements of GB1499-1988 Water-rolled by HRB335 G460 performance meets GB1499-1997 standard |
||
|
φ10 φ12、φ14 Q235-HRB335 Q235-HRB335 HRB235-HRB400 HRB335-HRB400
φ16、φ18、φ20、φ22、φ25、φ28、φ32、φ36、φ40 HRB335-HRB400 HRB335-G460B HRB335-G500B |
 |
|
|
PLC control system |
Water control system |
|
|
The water-through cooling methods currently used in the market are basically divided into two types, one is water tank type (represented by Danieli form) and the other type is open type (in the form of Bomini) Representation) In the form of water tank, it is very inconvenient to process the steel and replace the nozzle, and it can not achieve the effect of quick replacement (handling steel accident), and the Pomi form can achieve the result of rapid replacement, so many manufacturers now use Pomi The water-cooling device in the form of Nie, but due to its water-cooled open form, a large amount of mist is generated during use, so that the entire plant is covered in water mist, which has considerable safety hazard relative to the rolling site. In this case, a quick-change waterproof mist-shaped water-cooling device has been developed, which adopts a venturi structure, and the advantages of both are improved in terms of replacement speed and waterproof fog.
|
||
.jpg) |
Danieli form water cooled valve table combination |
|
 |
Danieli reverse nozzle (high line) |
|
|
The water cooler is designed and manufactured for rolling round steel and rebar of φ60～φ90. The water cooler adopts the reverse water cooling form. Due to the relatively slow speed of the large diameter round steel, the water cooled form can increase the heat exchange amount, and Reverse water cooling reduces the amount of water that the rolled piece takes out of the water cooler, so that the sealing effect is good;
Water-cooling water heater assembly for large diameter bar cooling
Danieli high-line water-cooled nozzle
Morgan high line water cooling nozzle |
The Morgan form water tank adopts the text tube structure and is used in the high-line pre-water cooling to increase the water cooling effect in the high-line medium-rolling room.
|
|
