Our common stainless steel precision parts are usually manufactured with conventional grades such as 303, 304, 316, 420. Stainless steel parts have good formability, compatibility, corrosion resistance and other characteristics, as well as strong rigidity. Heavy industry, light industry, or our daily lives can be seen everywhere.
Under normal circumstances, people will call alloys with chromium content greater than 12% or nickel content greater than 8% as stainless steel. This material has good corrosion resistance in the atmosphere or in a corrosive environment, and can It has very strong rigidity under extremely high temperature (usually >450°C). The steel with chromium content of 16%-18% is called acid-resistant steel or acid-resistant stainless steel. It is used in aerospace, petrochemical, construction There are different requirements for materials in transportation and kitchen utensils.
A. Large cutting force: The plastic deformation of stainless steel is large during the cutting process, which leads to an increase in cutting force. Stainless steel has serious work hardening and high thermal strength, which further increases the cutting resistance, and it is more difficult to curl and break the chips.
B. Severe work hardening: the plasticity of stainless steel is large, the character is distorted during plastic deformation, and the strengthening coefficient is large; and the austenite is not stable enough, under the action of cutting stress, part of the austenite will be transformed into martensite.
C, the chips are not easy to break, easy to bond: the plasticity and toughness of stainless steel are very large, and the chips are continuous during CNC machining, which not only affects the smooth operation of the operation, but also crushes the processed surface. Under high temperature and high pressure, stainless steel has a strong affinity with other metals, and it is easy to produce adhesion phenomena and form built-up tumors, which not only aggravates tool wear, but also tears and deteriorates the processed surface.
D. High cutting temperature: The plastic deformation and friction with the tool are large during cutting, and the cutting heat is generated; a large amount of cutting heat is concentrated on the interface between the cutting area and the tool-chip contact, and the heat dissipation condition is poor.
E. Large linear expansion coefficient: The linear expansion coefficient of stainless steel is about 1.5 times that of carbon steel. Under the action of cutting temperature, the workpiece is prone to thermal deformation and the dimensional accuracy is difficult to control.
F. The tool is easy to wear: The affinity effect in the process of cutting stainless steel causes the bonding and diffusion between the tool and the chip, which causes the tool to produce bonding wear and diffusion wear, resulting in crescent craters on the rake face of the tool, and the cutting edge The formation of tiny spalling and gaps; coupled with the high hardness of carbide (such as TiC) particles in stainless steel, direct contact with the tool during cutting, friction, abrasion of the tool, and work hardening phenomenon, will increase the wear of the tool.
Through the above analysis, we know that the basic performance of the cutting processing difficulties of stainless steel precision parts is about cutting strength, work hardening, high viscosity, high temperature, high linear expansion coefficient and easy to wear tools. When we understand that stainless steel processing has For such characteristics, corresponding measures such as selecting machine tools, selecting tools, selecting cutting lines, cutting amounts, and cutting fluids are used to ensure the quality of product processing.