The purpose of this project was to investigate whether plates form a heat affected zone (HAZ) when plasma arc cutting in stainless- and nickel base steels and see what effect this has on the material. This project was initiated after a customer reclamation where cracks in the center of the plate were observed after it had been plasma cut. Additionally, there is limited knowledge about whether the finished product is affected by plasma arc cutting. The goal of this thesis was to find differences between HAZ and BM, investigate material structure (both grainsize and grain density), evaluate cracks in HAZ compared to BM in a bend test, determine corrosion resistance and analyze the effect from different cutting parameters. The methodology contained a literature study, test preparation and experimental testing. Three different steel grades were used in the study, these were: austenitic 304L hereby called 18-8L, a duplex steel 2205 and nickel base alloy 825. Test preparations included manufacturing test coupons through plasma cutting, there were three different settings used for this. The first changed parameter was to increase the amperage above nominal value, the second was decreased by cutting speed below nominal value and finally a standard parameter. The idea for this was to test the various parameters Individually. Coupons were thereafter machined into the required test pieces, tests were chosen based on the literature study and some tests were added due to authors’ curiosity. All tests were performed either exactly or as close to the standardized testing procedures dictated. The most significant findings indicate that cutting speed affects the material more than amperage. When alloy 825 were observed it seemed that pieces cut with reduced speed were in clear majority of those that cracked in the center during corrosion testing. In these cracks sigma phase was found which is the reason for the weakness of the material. Those other alloy 825 pieces didn’t show any indication of the same behavior which results in the conclusion that reduced speed in cutting have bigger effect on the material. Neither of 2205 nor 18-8L showed any indication of being sensitive to changes in parameters. HAZ measurements showed small zones ranging between 10-100 micrometers which made it impossible to perform hardness and microstructure tests. SEM results showed confirmation of both sigma phase and precipitates. Conclusions from the study is that alloy 825 is sensitive to heat input when plasma cutting, that reduced cutting speed should be avoided to minimize the risk of creating sigma phase and cracks. When analyzing test pieces one conclusion is that because increased amperage does not seem to affect the material, the machine should be able to cut faster due to this. Generally, the effect is relatively small except for when the material is subjected to heat for extended time.