Modelling and Simulation of Phase Formations in Martensitic Stainless Steels

Modelling and simulation of solidification processes and solid-state phase transformation have become key instruments in the field of alloy development and heat treatment optimization. Apart from equilibrium-controlled processes, also diffusion-based effects need to be considered. This contribution presents some typical approaches at the example of martensitic stainless steels. Important aspects affecting the production and properties of these steels, such as alloying limits with nitrogen, the formation of ledeburitic structures, or the retained austenite content after heat treatment, can be predicted with reasonable accuracy.

Effect of Forging Deformation and Cooling on Mechanical Properties of Martensitic Stainless Steel

Stainless steel has good mechanical properties compared to other materials for strength and hardness, usually it will increase in hardness after hardening or forging. The purpose of this study was to obtain information about: The value of hardness and tensile strength of martensitic stainless steel forging with various deformations and cooling. The research method used is an experimental method, namely by forging on martensitic stainless steel with variations in deformation and cooling rate. Variations of forging deformation used are 25%, 50%, and 75%. The cooling media used are water, oil and air. The results of forgings with various cooling media were tested for tensile strength and tested for hardness using the Rockwell C (HRC) method. It was found that the higher the value of forging deformation, the higher the value of strength and hardness of martensitic stainless steel. This is because more and more martensite structures are recrystallized. In addition, it was also found that water and air cooling media gave an increase in the hardness of martensitic stainless steels. This is influenced by the cooling rate, where the higher the cooling rate, the more martensite structures formed, thus increasing the hardness value. The increase in hardness value is proportional to the increase in yield strength and tensile strength.

Characterization of 410NiMo Coatings Deposited By Thermal Spray And Re- Cast With TIG On CA6NM Martensitic Stainless Steel Against Cavitation Erosion

In most applications, martensitic stainless steels are subjected to operating conditions in which good mechanical properties and wear resistance are required. CA6NM is a soft martensitic stainless steel that has high shear stress and toughness, good resistance to corrosion and cavitation, and better weldability than conventional martensitic stainless steels. These steels are susceptible to cavitation erosion which is the process of removing material due to the progressive action of erosive wear caused by the implosion of bubbles close to the surface of the mechanical element. Welding and thermal spraying are normally used to produce coatings when there is a need to increase the useful life of systems and parts, or in some cases for refurbishing. In this work 410NiMo martensitic stainless steel, in the form of wire and rod, were deposited by electric arc and flame thermal spraying processes respectively over a CA6NM martensitic stainless steel substrate. In order to improve the layer performance the sprayed coatings were remelted by the TIG welding process. The specimens were evaluated by accelerated cavitation according to ASTM G32-1 0 standard, Vickers microhardness, optical microscopy, X-ray diffraction, SEM and EDS. The tests showed coatings with low porosity and resistant to erosion by cavitation comparable with welded coatings. Making thermal spray with reflow by the TIG process an alternative in the application of this type of coating.

Microstructural Changes During Short-Term Heat Treatment of Martensitic Stainless Steel—Simulation and Experimental Verification

Short-term heat treatments of steels are used for tools and cutlery but also for the surface treatment of a variety of other workpieces. If corrosion resistance is required, martensitic stainless steels like AISI 420L or AISI 420MoV are typically used. The influence of short-term heat treatment on the different metastable states of the AISI 420L steel was examined and reported in this article. Starting from a defined microstructural state, the influence of a short-term heat treatment is investigated experimentally with the help of a quenching dilatometer and computer assisted simulations are carried out. With the results obtained, a simulation model is built up which allows to compute the microstructural changes during a short-term heat treatment to be evaluated without the need for an experiment. As an indicator, the value of the martensite start temperature is calculated as a function of different holding times at austenitizing temperature. The martensite start temperature is measured by dilatometry and compared to calculated values. Validation of simulated results reveals the potential of optimizing steel heat treatment processes and provides a reliable approach to save time, resources and energy.