Shapes and parts can be cut rapidly using plasma, laser, and water jet.  There are some important considerations that must be considered when choosing the method.  Plasma and laser cutting are high heat input cutting process that melt a localized area of metal.  During the cutting process, a high pressure gas stream blows the liquid metal down and out of the cut, to create the cut edge.  Water jet cutting is a completely solid state process where finely graded garnet is mixed in with a high pressure water stream where the pressure and abrasion are sufficient to make the cut. 

It is important to note that with laser and plasma cutting, there is a zone of melted and resolidified metal at the edge of the cut and a heat affected zone just adjacent to the melted zone.  Plasma can leave a heat affected zone as deep as 0.250 inches into the metal.  Laser cutting leaves a much smaller heat affected zone, typically 0.063 inches or less.  For martensitic materials such as 410, 446, and 17-4 stainless steels, this leaves an untempered martensite edge, which is susceptible to quench cracking.  Ideally, these two processes should not be used to cut martensitic metals.  However, because of productivity and cost, some insist on using these processes.  In such cases, materials should be cut with at least an extra 0.500 inches on all sides, and it must be understood that this margin of safety may not be sufficient.  For these materials, the best solution is to either saw cut plate, or water jet cut shapes. 

Care also needs to be taken in deciding to use plasma or laser on the duplex family of stainless steels or 6 Mo and higher austenitic stainless steels.  The reason for this is that the melting process can liberate or alter the deliberate additions of both nitrogen and molybdenum in these materials, and negatively impact  pitting corrosion resistance.  The reason for this can be understood by understanding the calculation for pitting resistance equivalent number (PREN):

PREN = %Cr + 3.3 x (%Mo + 0.5 x W%) + 16 x %N
(See PREN Calculator HERE)

By decreasing the nitrogen, and to a lesser extent the molybdenum content, the pitting resistance in cut and/or weld areas can be severely reduced.  For welds, this issue is overcome by using over-alloyed filler metals.  There is no compensation for a cut edge, except using a different process that does not create a liquid/resolidified zone, such as water jet cutting or plate cutting.  Another option would be to add cut material wider and longer, and grind away the extra material that would include the resolidified zone.

In short, in materials where creating a melted and resolidified zone, the process makes some materials much more susceptible to cracking, and much more susceptible to corrosion.

For heat resistant austenitic materials that will see very high temperatures, where they will turn color from the heat, there is far less concern about these melted and resolidified areas since there is no phase transformation that will result in a hardenable structure, and thus no driving force for cracking.  In these high temperature environments, the melted and resolidified zones present little to no concerns to their use.  In these cases, laser and plasma cutting are quite acceptable cutting practices.