Waste heat treatment steel bars for reinforced concrete (GB 1499-91) (2)

Heat Treating Steel Reinforcing for Reinforced Concrete

Steel reinforcing helps to strengthen concrete and improve its durability over time, so it is important that is has been properly heat-treated in order to properly bond the reinforcing bars to the concrete. The process of heat treating steel reinforcing for reinforced concrete is determined by a variety of different standards, such as GB 1499-91.

GB 1499-91 is the Chinese concrete reinforcing standard for heat treating steel reinforcing in reinforced concrete. It provides requirements for the components, processes and tests of the heat treatment process. According to this standard, the steel bars must be hot-dipped galvanized, cold-rolled and of low carbon artificial or mild steel. The steel bars must then be heated at 730-900oC and slowly cooled in the range of 400-500oC. This heat treatment is necessary in order to strengthen the steel and to enhance its resistance to corrosion by galvanizing the surface.

In order to make sure the heat treatment meets the standard specified in GB 1499-91, the steel bar must be tested according to certain parameters. The most important one is to ensure that the steel bar has the right combination of strength and ductility. The ductility is measured by performing a tensile test on the steel bar, while the strength is usually determined by performing a bend test. Additionally, the surface of the steel should be checked for any cracks, signs of corrosion or other defects that may affect the quality of the steel bar.

The standard also specifies the types of tests that should be performed in order to measure the heat treating process. These tests include metallographic examination, hardness testing, chemical analysis, and microstructure evaluation. Metallographic examination can be used to determine the microstructure of the steel and evaluate the grain structure. Hardness testing measures the strength and toughness of the steel, while chemical analysis can be used to determine the composition of the steel. Microstructure evaluation helps identify any imperfections or defects in the steel, as well as any changes in the microstructure due to heat treatment.

In order to ensure that the steel bars comply with GB 149-91, manufacturers must also meet certain requirements for their production processes. This includes properly cleaning and preparing the steel before the heat treating process and properly monitoring the temperature during the process. After the heat treating process is completed, the steel should be tested and inspected to ensure it meets the standard.

Heat treating steel reinforcing for reinforced concrete is an important process that ensures that the steel bars will properly bond to the concrete and provide the necessary strength and durability. By following the standards specified in GB 1499-91, manufacturers can ensure that their steel reinforcing meets the necessary requirements in order to provide the best possible reinforcement to the concrete.

Hot - dip galvanized ribbed bars for reinforced concrete (GB 1499- 91) Part 2)

Hot dip galvanizing is a protective zinc coating applied to steel bars used in reinforced concrete. It protects the concrete structure from corrosion. Hot dip galvanizing process is done by coating the steel bar with molten zinc and passivating a thin layer of zinc on it.

The hot dip galvanizing ribbed bar (GB 1499-91) Part 2 prescribes the requirements, test methods and inspection rules for the hot dip galvanized ribbed bars in construction engineering. Key points include: the maximum imperfection of the rod, the performance requirements for the zinc coating, the tests for the tensile strength and bending strength of the product, the rules for the size of the test specimen for each product, and the sampling method for the inspection of the surface quality.

To ensure the quality of the hot-dip galvanizing ribbed bars, the following points need to be taken into consideration during processing:

1.Hot-dip galvanizing technology used should meet customer requirements;

2. The hot-dip galvanizing baths must be clean and the temperature must be kept stable;

3.The mechanical cleaning process before galvanizing should be qualified;

4. On-line inspection of the zinc coating shall be carried out during galvanizing;

5. Chemical pickling is also required in addition to mechanical cleaning;

6. Quality control should be enhanced and monitored at regular intervals.

By following these procedures and taking preventive measures, hot-dip galvanizing ribbed bars can be applied in critical reinforced concrete applications. Steel bars are exposed to a number of hazardous environments, and having a protective layer of hot dip galvanization provides an additional layer of protection against such aggressive environments.