Answers

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  Differences in Production Processes between Cold Rolling and Hot Rolling?

  The production process of hot-rolled coils involves heating continuously cast slabs or rough-rolled slabs in a furnace to approximately 1250°C, bringing them to a red-hot, plastic state. They are then rolled under high pressure in multiple passes on roughing and finishing mills, ultimately coiled into coils.
  Its core characteristics are:
  1. High production efficiency and relatively low cost.
  2. Typically thicker products, commonly ranging from 3.0mm to over 20mm; thicker products require production as medium-thick plates.
  3. Due to the high-temperature rolling, a dark blue oxide scale (iron oxide scale) forms on the surface, resulting in a rough surface (rough texture). Dimensional accuracy and shape control are relatively poor, with thickness tolerances typically within ±10 microns.
  4. Mechanical properties include lower strength but good plasticity and ductility; the internal structure is equiaxed crystals.
  
  Cold-rolled coils, on the other hand, use hot-rolled pickled coils as raw material. After the oxide scale is removed in the pickling line, the hot-rolled coils are rolled at room temperature.
  Its core characteristics are:
  1. Extremely high product precision. Wide thickness range, from 0.3 mm to 3.0 mm or even thinner, with thickness tolerance controllable within ±1 micrometers, and a straight sheet shape.
  2. Excellent surface quality. Various exquisite surfaces can be obtained through subsequent processing, such as 2B (bright surface after cold rolling followed by heat treatment, pickling, or similar treatment), BA (bright annealed mirror finish), No.3/4 (ground surface), etc.
  3. Changes in mechanical properties. Cold work hardening significantly improves the material's strength, hardness, and fatigue resistance, but reduces plasticity. To restore plasticity, eliminate internal stress, and obtain the required mechanical properties, annealing treatment must be performed after cold rolling, followed by temper rolling (finishing) in the final stage.

  
  
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  What is the silicon content of non-oriented silicon steel?

  Non-oriented silicon steel, also known as electrical steel, is a special type of steel used in the cores of electromagnetic equipment such as motors, generators, and transformers because it reduces power loss. It is economical and meets the requirements of high-efficiency, high-power motors.
  Non-oriented silicon steel (Prices) is a ferrosilicon alloy containing 0.8%-4.8% silicon, produced through hot and cold rolling into thin sheets less than 1mm thick. Adding silicon increases the resistivity and maximum permeability of iron, while reducing coercivity, core loss (iron loss), and magnetic aging.
  It is widely used in the home appliance industry, motor manufacturing, various motor components, and drive module components for new energy vehicles.

  
  
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  What are the applications of rock bolts?

  Anchor bolts have a wide range of applications. Firstly, in mining operations, they serve as the core support for the roof and side walls of underground tunnels and working faces, effectively preventing roof falls and rib failures. Secondly, in tunnel and underground engineering, anchor bolts, in conjunction with shotcrete, form the primary support system to control rock mass deformation, constituting a key technology in New Austrian Tunneling Method (NATM) construction. Furthermore, anchor bolts play an irreplaceable role in slope stabilisation, deep excavation shoring, and the stabilisation of dam foundations and reservoir banks in water conservancy and hydropower projects. Finally, anchor bolt technology is indispensable in construction projects for anti-floatation anchors, foundation reinforcement, and the addition of storeys to existing buildings. In summary, by applying active or passive anchoring forces to rock and soil masses, anchor bolts extensively ensure the safety and stability of various geotechnical engineering projects.