Cold hardening of 0Cr18Ni9 (AISI304) and 00Cr19Ni10 (AISI304L)

Cold Working Hardening of 0Cr18Ni9 (AISI304) and 00Cr19Ni10 (AISI304L)

Cold working is a process of shaping metal with the help of plastic deformation. It makes the metal stronger in comparison to its initial form, yet with similar properties. In cold working procedure, metal is put under pressure at room temperature or lower in order to increase its strength and hardness. Cold worked materials are used very commonly in a variety of applications due to their high strength and elevated resistance to both corrosion and cracking.

0Cr18Ni9 (AISI304) and 00Cr19Ni10 (AISI304L) are both austenitic stainless steels with similar yet also variable properties in terms of strength, hardness and corrosion resistance. Both of them can be cold worked, as well as subject to traditional hot working by heating, working, and cooling processes.

0Cr18Ni9 (AISI 304) exhibits very good formability in cold working, yet it has its limitations. One of the main drawbacks of 0Cr18Ni9 (AISI 304) cold working is the high rate of work hardening, i.e. strain hardening which occurs during cold deformation of the material. With each successive working process, the material become harder, resulting in much bigger deformation forces being required in order to deform it further. Also, 0Cr18Ni9 (AISI 304) is also susceptible to stress corrosion cracking when it is cold worked.

In order to avoid these issues with 0Cr18Ni9 (AISI 304) cold working, 00Cr19Ni10 (AISI 304L) is usually considered to be a better choice in terms of cold working. This is due to the fact that it is more ductile, and therefore less prone to work hardening which can lead to stress corrosion cracking. Furthermore, 00Cr19Ni10 (AISI 304L) is also more resistant to both thermal and chemical aggression when it is cold worked, compared to 0Cr18Ni9 (AISI 304).

Cold working is a very important step in material processing, and so considerations of the particular materials must be taken into account. In the case of 0Cr18Ni9 (AISI 304) and 00Cr19Ni10 (AISI 304L), 00Cr19Ni10 (AISI 304L) could be said to be the more suitable of the two for cold working due to its greater ductility and enhanced resistance to corrosion and stress.

The combination of cold working and austenitic stainless steels in order to produce stronger and harder materials is used extensively in the industry. The cold working process is able to produce materials that are stronger and more resistant to corrosion and cracking, making them ideal for a variety of applications, from construction to automotive. Cold working techniques are utilized to create complex shapes and to increase the overall strength and hardness of materials, and with the correct properties, austenitic stainless steel can become even more resistant to various types of stress and strain. Therefore, 0Cr18Ni9 (AISI 304) and 00Cr19Ni10 (AISI 304L) can be cold worked in order to shape them into their desired applications and achieve the desired strength and hardness levels.

Cold working hardening of AISI 304 and AISI 304L Steels

AISI 304 and AISI 304L steels are two of the most commonly used austenitic steels, composed of approximately 18-20 % chromium and 8-10.5 % nickel by weight. While both of these grades possess similar chemical compositions, the difference in their mechanical properties lies in the additional molybdenum present in AISI 304L steel. As a result, AISI 304L has slightly lower mechanical properties than AISI 304.

Cold work hardening is a process of strengthening a material either by increasing its tensile strength or yield strength. It involves reshaping a material into a new form or thickness by applying a large amount of stress without warming it above its recrystallization temperature. Cold working on austenitic steels like AISI 304 and AISI 304L results in an increase in strength along with a decrease in ductility.

AISI 304 and AISI 304L steels exhibit similar characteristics when cold worked, although their properties vary somewhat. Cold working AISI 304 and AISI 304L increases their yield strength by 110 to 140 MPa and 130 to 170 MPa, respectively. In addition, AISI 304 and AISI 304L also exhibit an increase in tensile strength when cold worked. The tensile strength of AISI 304 increases to an average of 550-700 MPa and 390-620 MPa for AISI 304L steel.

Cold working on AISI 304 and AISI 304L also results in an increase in their hardness. Cold working increases the Vickers hardness of AISI 304 by 1-2 % and AISI 304L by 2-4 %. While both steels are strengthened by cold work hardening, the increase in hardness is significantly higher for AISI 304L due to its lower carbon content.

In conclusion, cold working is very effective in increasing the strength of AISI 304 and AISI 304L steels, although the strength increase is higher in AISI 304L due to its lower carbon content. It is important to note that the degree of cold work hardening is dependent on the type of cold deformation applied, the thickness, temperature and strain rate.