Mechanical Properties of Several Newly-Developed Substrate Steels in China
Discovered some decades ago, Chinese steel industry has taken numerous technological advancements, transforming itself from “catch-up” to “leading edge” in the global market. Recently, numerous newly-developed substrate steels have been a great contribution to the industry. As such, it is essential to take a further look at the mechanical properties of those steels, from which their applications can be determined.
Uses of Substrate Steels
Different types of steels possess different characteristics, allowing for distinctive uses of them. Generally, substrate steels are excellent for making car body and parts which not only have to be strong, but also provide a reliable safety measure for the driver. Besides, substrate steels also have wide range of applications such as in the manufacture of electro-mechanical components, bridges, high-tech medical equipments, and etc.
High Strength Low-Alloy Steels (HSLA)
The development of high strength low-alloy (HSLA) steels has been one of the major achievements in Chinese steel industry in recent decades. These kinds of steels offer better mechanical properties than the regular steels, making them various ranges of applications. In addition, they tend to be more cost-effective, easy to weld, and have greater ductility than other particular steels.
One example of HSLA would be 17Mn4 that could achieve tensile strength of 550-740 MPa and yield strength of 390-550 MPa. 17Mn4 is commonly used for making car body parts. Additionally, a newly-developed steel called H450LA provided by Baosteel can produce good machining qualities with high strength values, making it more suitable for electro-mechanical components such as transmission shafts.
Laser Welded Steel
Compared to the arc welded steels, laser welded steel can provide better strength in welded joints and smoother weld contours. It is particularly advantageous for car body parts in order to minimize the time and cost for assembly. It is quite common to find this type of steel being applied in the automotive industry.
For instance, the laser welded steel DQAAEX-DJ manufactured by Shougang Group is provided with outstanding surface quality and mechanical property. This grade of steel has excellent formability, weldability and dimensional stability, thus making it suitable for car body parts. It is reported that DQAAEX-DJ can achieve tensile strength of 410-520 MPa, yield strength of 340-450 MPa, and total elongation of up to 28%.
Conclusion
In conclusion, several newly-developed substrate steels have been successfully launched in China and these steels offer improved mechanical properties, making them suitable for a wide range of applications. Among them, HSLA steels and laser welded steels are particularly outstanding due to their cost efficiency and optimized weld properties, while they can usually achieve tensile strength and yield strength of 500-800 MPa and 340-550 MPa respectively. With the advancement in steel research and industrialization, it is expected to further introduce more suitable substrate steels in the Chinese market.