What is Cast Iron?

What is Cast Iron?

The material consists of iron with more than 2% of carbon.

Cast iron is a very wide range of consumer as well as commercial applications.

Types of Cast Iron

1. Gray Cast Iron

Most common consists of small fractures of a graphite micro-structure which is responsible for creating the appearance of a gray color.

The gray cast iron offers various compressive strengths as steel. This as a result makes it a popular choice for metal applications that can involve compressive strength.

2. White Cast Iron

It has an off-white color, which in turn results in iron compounds that are known as cementite.

White cast iron is known to be hard, so having excellent resistance against abrasions.

3. Ductile Cast Iron

Also known as nodular cast iron it is a type of soft, ductile iron alloy accompanied by a high carbon content.

Its graphite is in the form of very tiny nodules that are accompanied with the graphite in the form of concentric layers which forms the nodules.

The properties are similar to the malleable iron, whereas the parts can be cast with larger sections.

4. Malleable Cast Iron

Created by using the heat treatment processes on the white cast iron.

As a result, the carbon in iron carbide is found to transform into either graphite or ferrite plus carbon.

The slow process forms spheroidal particles instead of flakes.

The properties of malleable cast iron are likely to be those of mild steel.

5. Alloy Cast Iron

The properties of the cast iron are changed by adding various alloying elements.

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Technical Progress Of High Speed Wire Rod Rolling Mill

Technical Progress Of High Speed Wire Rod Rolling Mill

Technical progress of high-speed wire rod rolling mill as followings: 

1) Continuous, torsionless and high-speed rolling. Roughing rolling and intermediate rolling are arranged alternately, and pre-finishing rolling is installed in front of the finishing mill. The maximum final rolling speed is designed to reach 120 m/s. 

According to the latest production practice, the maximum rolling speed will be guaranteed according to different specifications of wire rods. For example, in 2010, Siemens Austria Steel United Corporation (Morgan Company was annexed by the company) designed and manufactured high-speed for Xuanhua Iron and Steel Company. The guaranteed final rolling speed of the wire rod rolling mill is small wire rod Φ5.5-7.5 mm | 112 m/s, Φ5mm | 105 m/s for medium and 85 m/s for small diameter 6 mm quenched threaded steel. 

Improving the finishing rolling speed of the wire rod mill is a systematic project. It involves not only the main rolling mill machinery and electrical equipment but also the number of finishing mills, the rack spacing, and the cooling system. It does not affect the mechanical properties of products because of the high finishing rolling speed and the high finishing rolling temperature. 

It also requires supporting equipment such as a spinning machine and flying shear to withstand the high-speed impact of wire rods. 

2) Adding reducing and sizing equipment to improve product accuracy and solve the temperature control problem in the wire rod finishing rolling process.

3) Increasing the cross-section of the feed billet can not only meet the need for an upstream continuous caster to improve the productivity and quality of the billet but also increase the coil weight and increase the productivity and yield of the wire rod rolling mill.

4) The qualified billet is heated and soaked directly into the heating furnace through the hot charging roller. The hot charging temperature can reach over 600 C, which improves the productivity of the heating furnace, reduces the energy consumption during billet heating and the loss of oxide scale during billet cooling and heating, and improves the metal yield.

5) Low-temperature rolling. The starting rolling temperature is controlled at 950 C. The stiffness of the mill stand and the capacity of the main motor can meet this requirement in order to achieve overall energy savings and reduce metal burning.

6) Controlled cooling and temperature rolling.

7) Single-pass system. All products (small 5.0-25mm) only need to change rollers on four reducing and sizing mills, and no rollers need to be changed for other mills, thus significantly improving the productivity and productivity.

8) The latest generation of spinning machines and winding stations. In the form of asymptotic bending, the ideal trajectory of wire moving in the spinning tube is given, so that the wear of the spinning tube can be reduced and the running stability can be achieved.

The 90m High-Speed Wire Rod Rolling Line Project In Ethiopia Start Production

The 90m High-Speed Wire Rod Rolling Line Project In Ethiopia Start Production

December,13th,2016, the 90m high-speed wire rod rolling line project in Ethiopia contracted and constructed by Hani Tech has been put into production at 10 am local time. This means the whole rolling project and all the steel rolling mills it contains customized for SHENZHEN STELL with an annual capacity of 300,000 tons have been officially accomplished and transferred.

This whole project of a wire rod rolling production line with an annual capacity of 300,000 tons only takes WEIKEDUO less than a year to construct, which seems really miraculous for it could cost 3 years of construction for a complex project like this. As an experienced professional manufacturer of metallurgical types of machinery like monoblock mills, hot rolling mills, flying shears, and other associated equipment, WEIKEDUO has dedicated itself to developing and providing advanced and durable machinery equipment for all our clients around the world.

This brand new rolling line in Ethiopia will provide more job opportunities for local people and government while it would also boost the local economy vigorously. The present Director of Investment from the Ethiopian government, Fitsum, has once again declared the fact that the Ethiopian government will encourage and support all Chinese companies with competitive advantages and good faith to invest and develop in Ethiopia as always. And they will provide a solid foundation for all these companies to grow.

The deputy director of the Eastern Industry Zone, Jiao Yongshun, has also congratulated the success of the project and indicated that this rolling project could be another achievement to our current One Belt and One Road Initiative.

The Additional Processing Steps In The Manufacture Of Cold Rolled Sheets

The Additional Processing Steps In The Manufacture Of Cold Rolled Sheets

The cold-reduced coil, as it exists, is very hard and possesses very limited applicability. It is very stiff and exhibits high amounts of spring back when bent. Therefore, this steel must be annealed (heated to high temperatures) to soften it and make it useful.

During the process of heating, the steel will be soft and can subsequently be used for a multitude of applications. Continuous annealing involves passing the steel through a high-temperature furnace in the form of a continuous ribbon. That is to say, the coil is fed from a payoff reel into the furnace. It reaches a high temperature when its passage through the furnace. The steel sheet cooled, and recoiled at the exit end of the furnace.

Whether the steel is batch annealed or continuously annealed, the specific properties of the steel sheet, after annealing, depend on the steel chemistry, the temperatures used during hot rolling, the amount of cold reduction, and the annealing cycle (time and temperature).

Whichever method of annealing is used, the steel is maintained under a protective (non-oxidizing) atmosphere using hydrogen and nitrogen to prevent oxidizing the steel while it is at high temperature. Furthermore, to prevent oxidation, the protective atmosphere is designed to clean the steel by breaking down the oils that are present after cold rolling and entraining the oil vapors in the hydrogen/nitrogen gases that are passed through the furnace.

The Adjustment Of Steel Rolling Mill

The Adjustment Of Steel Rolling Mill

Before the steel rolling mill is used, the roll pass, controlling plate shape, and backup roll should be adjusted according to the requirement; and the fixed position of the rolls in the rolling mill should be maintained. The workload of the rolling bearing is heavy and varies greatly, so the friction coefficient of the bearing is required to be small. After determining the product rolled by the rolling mill, the line speed of the rolling mill can be basically determined. The hardness of the raw materials is measurable. The rolling stock of the rolling mill is determined by changing the plastic deformation size.

Usually, the newly installed steel rolling mill has a running-in process. During the running-in process, the rolls are operated in a second operation, and the operation speed is 50%, 65%, 75%, and 85%. Different steel rolling mill models use rolls with different materials and specifications for different rolling products.

After the steel rolling mill is installed, the gears of the reducer and the gearbox need to have meshed, the rolling speed is too fast, and the torque is enhanced. After the normal operation of the rolling mill for 30 days, stop the rolling mill and check the meshing of the large and small gears, and waits for everything to be normal, the rolling speed can be increased.

Under normal circumstances, it is not necessary to adjust the rolling speed. The rolls in the steel rolling mill are constantly worn during the running process. In order to keep the rolling mill stable in the controlled rolling requirements, the roll must be repaired in time, and the rolls need to be replaced in serious cases.

The steel rolling mill needs labor, even the automated equipment needs to be monitored manually in the console. The conveyor roller and shearing machine located in the automatic rolling mill must be strictly controlled during operation to avoid the failure of stacking steel or jamming. If the wear of roll and guide exceeds the specified range, it needs to be replaced.

The rolling of the billet causes the roll to be squeezed instantaneously, and the bearing is subjected to correspondingly high pressure, thereby affecting the product size of the rolled steel. We may also need to make in-depth improvements, but the ultimate goal is to get better steel rolling mill equipment.

The Advantages And Disadvantages Of Electric Arc Furnace

The Advantages And Disadvantages Of Electric Arc Furnace

There are several essential elements that caused the evolution of the electric arc furnace:

1) The increasing quantity of scrap steel;

2) The rapid development of the entire steel industry. The supply and the price of electricity become stable, which makes it possible to generalize the arc furnace;

3) The arc furnace tends to be larger and more powerful;

4) Less investment, quick to construct, and fast cost recovery;

5) The temperature and the component of the molten steel can be controlled with accuracy. The arc furnace can also smelt various kinds of different steels.

Compared with others, the electric arc furnace also has several obvious advantages:

1) The arc furnace can heat the furnace and the steel up to 4000-6000℃ directly and smelt special steels that contain refractory elements like W and Mo.

2) The arc furnace could remove the toxic gases and the inclusions while deoxidizing and desulfurating.

3) High flexibility. The arc furnace is capable of engaging production continuously or intermittently.

Currently, owing to the development of related technologies, the electric arc furnace could be well-integrated with traditional steel-making processes. But there are also several deficiencies that need to be improved:

(1) The arc can only generate point-like heating sources, which will cause uneven heat distribution in the furnace.

(2) The arc will react with the furnace gases and vapor and release large quantities of H2 and N2.

With further improvement of the electric arc furnace, new smelting techniques will embrace a brighter prospect.