What are the characteristics of stainless steel cutting processing?

The cutting performance of stainless steel is weaker than that of carbon steel. If the cutting performance index of ordinary No. 45 steel is 100%, the relative cutting performance of austenitic stainless steel 1Cr18Ni9Ti can only reach 40%; that of ferritic stainless steel 1Cr28 is 48%; that of martensitic stainless steel 2Cr13 is 55%. It can be seen that the machinability of austenitic and austenitic ferritic stainless steels is weak.
There are many characteristics in the cutting of stainless steel materials, such as severe work hardening. Among them, the work hardening phenomenon of austenite and austenite + ferrite stainless steel is prominent. The strength of austenitic stainless steel after hardening is as high as 1470-1960MPa. The depth of the work-hardened layer can be as high as 1/3 of the cutting depth or even greater; the hardness of the hardened layer is 1.4-2.2 times stronger than the original. Stainless steel has greater plasticity, is easily distorted during plastic deformation, and has a very high strengthening coefficient. In addition, austenitic stainless steel has poor stability. Under the action of cutting stress, some austenite will transform into a martensite structure; and then In addition, compound impurities are easily decomposed under the action of cutting heat, resulting in the formation of a hardened layer during cutting. This will seriously affect the subsequent processes.
The second feature is the high cutting force. The plastic deformation of stainless steel during the cutting process is high, especially austenitic stainless steel, which will increase the cutting force. In addition, stainless steel is severely work-hardened and has high thermal strength, which will further increase the cutting resistance, making it more difficult to curl and break chips. Therefore, the cutting force for processing stainless steel is high. For example, the unit cutting force for turning 1Cr18Ni9Ti is 2450MPa, which is about 25% higher than that of No. 45 steel.
The third characteristic is that the cutting temperature is high, and the plastic deformation and friction with the tool are very large during cutting, resulting in a lot of cutting heat. In addition, the thermal conductivity of stainless steel is higher than that of No. 45 steel, so a large amount of cutting heat will be concentrated in the cutting area and On the surface where the cutting chips come into contact, the heat dissipation conditions are worse. Under the same conditions, the cutting temperature of 1Cr18Ni9Ti is about 200°C higher than that of No. 45 steel.
The fourth characteristic is that the chips are not easy to break and are easy to bond. Stainless steel has high plasticity and toughness. The constant chips during turning will not only affect the smooth operation, but also squeeze the processed surface. Under high temperatures and high pressures, stainless steel has a high affinity with other metals and can easily form adhesion and lead to built-up edges, which not only aggravates tool wear, but also causes tearing and deterioration of the machined surface. Martensitic stainless steels with lower carbon content are more obvious in this regard.
The fifth characteristic is that the tool is easy to wear. Under the action of the affinity when cutting stainless steel, the bonding and diffusion between the tool and the chips will occur, resulting in bonding wear and diffusion wear of the tool, resulting in the formation of crescents on the rake face of the tool. The cutting edge will also produce tiny peelings and chips; in addition, the carbide particles in stainless steel have very high hardness, which will directly contact and rub the tool during cutting, and scratch the tool. In addition, work hardening will also cause the tool to wear faster.