Here we analyze the machining characteristics of stainless steel turned parts. The summary is as follows, hoping to be helpful to you.
The cutting performance of AISI304 austenitic stainless steel is poor, mainly manifested in large cutting force, severe work hardening, high local temperature in cutting zone, and tool adhesion and wear.
Due to the large plastic deformation during cutting and the relatively low hardness (hardness ≤ 187HBS) of AISI304 austenitic stainless steel, especially at higher temperatures, it can still maintain a higher strength (the strength of ordinary steel decreases significantly when the cutting temperature increases), which leads to the larger cutting force of AISI304 austenitic stainless steel.
Under conventional cutting conditions, the unit cutting force of AISI304 stainless steel is 2450MPa, more than 25% higher than that of 45 steel.
During cutting of AISI304 stainless steel, there is obvious plastic deformation, causing serious distortion of the crystal lattice. At the same time, due to the defects in the stability of the austenitic structure, a small part of the austenitic structure turns into martensite during this process.
In addition, impurity compounds in the austenitic structure will decompose due to heating during the cutting process, and the dispersed impurities will form a hardened layer on the surface, making the work hardening phenomenon very obvious. The hardened strength σb is above 1500MPa and the depth of the hardened layer is 0.1-0.3mm.
Due to the large cutting force and the difficulty in separating chips, a large amount of energy is consumed to separate the chips during the cutting of AISI304 stainless steel. Under conventional conditions, cutting AISI304 stainless steel requires about 50% more energy than cutting low carbon steel, resulting in more cutting heat.
The thermal conductivity of austenitic stainless steel is poor, and the thermal conductivity of AISI304 stainless steel is only one-third of that of 45 steel, so the temperature in the cutting zone is relatively high. A large amount of cutting heat is concentrated on the cutting zone and the contact surface between the tool and the chips, and 20% of the heat enters the tool (this value is only 9% when cutting ordinary carbon steel) under the same cutting conditions. Therefore, under the same cutting conditions, the cutting temperature of AISI304 stainless steel is about 200-300°C higher than that of 45 steel.
Due to the high temperature strength and work hardening tendency of austenitic stainless steel during cutting, the cutting load is heavy. The affinity between austenitic stainless steel and the tool and chips is significantly increased during the cutting process, resulting in inevitable phenomena such as adhesion and diffusion, and the formation of "chip tumors", causing tool adhesion and wear.
Especially, the hard inclusions formed by a few carbides accelerate tool wear, even causing edge breakage, greatly reducing the service life of the tool, and also affecting the surface quality of the machined parts.