The Analysis and Prevention Measures of High-speed Steel Tool Quench Cracking
1 Introduction
High speed steel tools are tools made of high speed steel material. Its function is to quickly process a variety of objects, materials and parts to achieve their desired shape and structure. It is widely used in engineering and industrial fields, especially in the machining industry, as well as in the automotive, aerospace and other industries. In the process of using high speed steel tool, quench crack easily occur,which cause great hidden trouble to engineering and industrial production. Therefore, it is necessary to analyze and study the causes of quench cracks to prevent them from happening.
2 The Cause of Quenching Cracks
There are many reasons that can cause quench cracks in the process of using high-speed steel tools. The main ones are as follows.
2.1 Structure Inhomogeneity
High-speed steel tools are processed according to the specifications for their use. If the specifications are not coordinated in the process of tool making, it will cause the molecular structure of the tool material to be unevenly distributed and shrinkage. The local expansion stress generated by this uneven heat treatment process will increase. When the shear stress generated by the cooling exceeds the yield limit of the material, cracks will appear.
2.2 Excessive Quenching Medium Temperature
High-speed steel tools are quenched in different media, such as water, oil, salt bath and other media. The higher their temperature is, the greater their cooling rate will be. If the temperature of the quenching medium is too high and the cooling rate is too fast, thermal stress will be generated in the material, which will be greater than the yield limit of the material, resulting in quench cracking.
2.3 Uneven Heating
In the quenching process,the heating process of the high-speed steel tool must be uniform, otherwise it will cause local overheating and poor heat dissipation layer. The result of this local overheating is that the cooling rate of local is not uniform, unbalanced thermal stress occurs in the material, which makes the surface of the tool produce cracks.
3 Prevention and Control Measures
In order to effectively avoid quench cracking of high-speed steel tools, we need to take the following measures to avoid it happening.
3.1 The Structural Design of the Tools
When designing the structure of the tools, the structure and size of the tools should be strictly determined according to the existing standards. So that it can avoid the uneven heat treatment that cause the structure inhomogeneity.
3.2 Scientific and Rational Select of Quenching Media
Different quenching media can be selected according to actual needs and application situation, so as to avoid using improper quenching media, namely, the media with too high temperature, which will cause the excessive cooling rate and quench cracks.
3.3 Proper Process Control
In the process of quenching,staffsada should control the heating process to ensure that the heating process is uniform. If the material overheats in local, we can reduce the temperature of the quenching medium accordingly. In the process of cooling, the cooling speed should be controlled within a reasonable range, and the cooling medium can be changed in time, so as to avoid the quench cracking caused by the too large thermal stress.
4 Conclusion
High-speed steel tools are widely used in various industries due to their high abrasion resistance and strength. However, in the process of using it, quench cracking often occur due to some operational errors and unstandardized processing technology. In order to effectively prevent quench cracking of high-speed steel tools, it is necessary to analyze and study the causes of quench cracking and take corresponding control and prevention measures.
