Martensitic steels parameters

High chromium in martensitic steels have strengths comparable to austenitic steels up to 500°C and present a greater resistance to the effect of radiation damage. For this reason, it is important to obtain parameters such as the solubility and permeability of hydrogen and its isotopes. 

The austenitic-ferritic steels, because of their two structural components also known as duplex steels, are chromium-nickel steels with chromium contents of about 21%-27%, and nickel contents of 4%-5%. They are usually made with about 3% molybdenum, nitrogen additions and a carbon content of < 0.03%. They reach the category of temperable martensitic steels with values for the 0.2% yield point of > 450 N/mm and are thus clearly above the austenitic steels. Worth mentioning are the good viscosity parameter values and the favourable fatigue strength properties of these steels, even in corrosive mediums. 

However, smdies performed in the past and confirmed through experiments performed recently [79,81] on both austenitic and ferritic/martensitic steels have shown that by increasing the oxygen activity in liquid sodium a degradation of mechanical properties is observed. In particular, the steels tested in these references showed a brittle behavior, which was dependent also on other parameters, such as the exposure time and the testing temperature. 

The enhanced strength and corrosion properties of duplex stainless steels depend on maintaining equal amounts of the austenite and ferrite phases. The welding thermal cycle can dismpt this balance therefore, proper weld-parameter and filler metal selection is essential. Precipitation-hardened stainless steels derive their additional strength from alloy precipitates in an austenitic or martensitic stainless steel matrix. To obtain weld properties neat those of the base metal, these steels are heat treated after welding. 

For steels that are most frequently used in the annealed or normalised condition the most important structural parameter that can be influenced by heat treatment is the grain size, although the extensive use of welding as a means of fabricating mild steels means that martensitic and tempered martensitic... 

Microscopic examination of a hardened 1.0 percent carbon steel shows no undissolved carbides. X-ray examination of this steel in a diffractometer with filtered cobalt radiation shows that the integrated intensity of the 311 austenite line is 2.33 and the integrated intensity of the unresolved 112-211 martensite doublet is 16.32, both in arbitrary units. Calculate the volume percent austenite in the steel. (Take lattice parameters from Fig. 12-5, A/corrections from Fig. 13-8, and temperature factors from Fig. 4-20.)... 

High-alloyed steels with a martensitic microstructure show machining results, which heavily depend on the workmaterial hardness and thus on the applied heat treatment. However, hardened and tempered martensitic stainless steels can be machined relatively well with suitable cutting parameters, tool materials, and coating systems, respectively. The dominant failure modes when using coated carbide tools for cutting hardened... 

Fig. 8.4 highlights the fact that, beyond the material nature, the key parameter governing the Fe dissolution is here the Cr content starting from 9% in the ferrito-martensitic EMI 2, which is therefore unsuitable for reprocessing with classical processes, to 16% with the 316 type steels which present no reprocessing problem at all. In Section 8.6 we discuss the possibility of specifying an advanced austenitic steel exhibiting a lower Cr content than classical materials of 300-series, and will have to keep in mind the rather poor behavior of the 12% Cr N9 material, CEA precursor of advanced austenitic materials. 

The influence of alloy composition on the ability of a steel alloy to transform to martensite for a particular quenching treatment is related to a parameter called hardenability. For every steel alloy, there is a specific relationship between the mechanical properties and the cooling rate. Hardenability is a term used to describe the ability of an alloy to be hardened by the formation of martensite as a result of a given heat treatment. Hardenability is not hardness, which is the resistance to indentation rather, hardenability is a qualitative measure of the rate at which hardness drops off with distance into the interior of a specimen as a result of diminished martensite content. A steel alloy that has a high hardenability is one that hardens, or forms martensite, not only at the surface, but also to a large degree throughout the entire interior. 

It is partially stabilized zirconias (PSZ) that have justified the resounding article ( Ceramic steel ) published in 1975 by Garvie et al. [GAR 75], The title suggests that a ceramic can exhibit the high mechanical performances associated with steel, but also that toughening mechanisms recall those used by steel manufacturers. The t- m transformation of zirconia is a martensitic transformation, in analogy with the transformation used to obtain martensite in tempered steels, and the role of microstructural parameters inZr02 is similar to what is observed in metals. 

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