Research and development of wear-resistant HARDOX400 steel plate with low welding crack sensitivity

    
    Introduction
    
    High wear resistance is essential for many components in industry, engineering, and construction due to the increasing performance requirements of today’s machines and equipment. One type of commonly used wear-resistant material is Hardox 400 steel plate, which is a quenched and tempered steel plate with a nominal hardness of 400 HB. This high hardness material offers excellent wear resistance and good formability. However, welded Hardox 400 can suffer from low welding crack sensitivity and can be prone to cracking during fabrication. To address this issue, research and development efforts have been executed to improve the welding performance and reduce the welding crack sensitivity of Hardox 400 steel plate.
    
    What is HARDOX400?
    
    Hardox 400 is a quenched and tempered steel plate produced by SSAB (formerly known as AvestaPolarit). It is developed for applications where high wear resistance is required. Thanks to its high hardness of 400 HBW, it provides superior performance in terms of abrasion resistance and strength. Hardox 400 is available in a variety of sizes and thicknesses, making it suitable for different applications from mining equipment and dump trucks, to oil rigs and bridges.
    
    What Is Welding Crack Sensitivity?
    
    Welding crack sensitivity is a measure of how prone a material is to cracking during welding. It is determined by testing a variety of specimens made of the material and measuring their crack susceptibility during welding. Cracking of welded components can be a major issue in some industries due to the potential for component failure, thus welding crack sensitivity is a critical property for selecting suitable materials for welding applications.
    
    Research and Development of Hardox 400
    
    Research and development efforts have been conducted to reduce the welding crack sensitivity of Hardox 400 steel plate. The main objective of this is to improve the weldability of Hardox 400 and minimize the risk of weld cracking. Several approaches have been taken to achieve this goal, such as changing the chemical composition, modifying the plate’s heat treatment process, and adding various alloy elements.
    
    The chemical composition of Hardox 400 was modified to enhance its weldability. After extensive testing and trials, some minor changes were made to the composition, such as the addition of Nickel to the plate. This resulted in the introduction of the new grade known as Hardox 400 NiMn. The new grade was developed and optimized for welding performance and exhibited improved crack resistance.
    
    In addition to the changes in the chemical composition, modifications were also made to the heat treatment process. For instance, the temperature of the quenching process was adjusted to reduce residual stresses in the material that are typically formed during welding. This improved the weldability of the material and further reduced the welding crack sensitivity.
    
    Finally, additional alloy elements were added to Hardox 400 to further reduce the welding crack sensitivity. This involved adding Copper, Chrome, Titanium and Molybdenum to the steel. These alloys were chosen carefully to provide a beneficial effect without adversely affecting the other properties of the steel. The introduction of these alloy elements improved the weldability and reduced the welding crack sensitivity of Hardox 400.
    
    Conclusion
    
    Hardox 400 is a high hardness, wear-resistant steel plate which offers excellent wear resistance. However, welded Hardox 400 can suffer from low welding crack sensitivity, leading to weld cracking during fabrication. To address this issue, research and development efforts have been executed to improve the welding performance and reduce the welding crack sensitivity of Hardox 400 steel plate. This involved changing the chemical composition, modifying the plate’s heat treatment process, and adding various alloy elements. As a result of these efforts, Hardox 400 has been improved, exhibiting improved weldability and reduced welding crack sensitivity.

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