Rene 65 is a nickel-based superalloy used in aerospace components such as turbine blades and disks. The microstructure in the as-received condition of the superalloy consists of about 40% volume fraction of gamma prime precipitates, which is so strong that thermomechanical processing is problematic. The aim of this work is to find a heat treatment to reduce hardness for manufacturing purposes without changing grain size in the final application. For the design of the heat treatments, Taguchi’s L8 matrix is used and the factors that are examined include cooling rate, hold temperature, hold time, and cooling method to room temperature.

The AISI 440B (DIN 1.2210, X90CrMoV18) steel is one of the hardest among martensitic stainless steels. This type of steel is used in a variety of industrial applications where wear and corrosion are determinant, such as molds, parts and tools for the automotive and biomedical industries. Their superior mechanical properties are due to its high carbon (0.75-0.95 % C) and chromium (16-18% Cr) contents. Suitable coatings can increase wear resistance and expand these materials usability range. Boride coatings, with their high hardness and wear resistance are good candidates for this purpose. Boride layers were obtained by boriding treatment in a salt bath (a mixture of sodium borate and aluminum). The layer properties, such as hardness, thickness, layer/substrate interface morphology and phases formed are influenced by steel composition. In this work, the layers produced on AISI 440B steel were harder, thinner, with a smoother interface when compared to plain carbon steels due the larger amount of alloying elements. In order to evaluate mechanical properties of borided layers in samples of stainless steel AISI 440B, Optical Microscopy (OM) microstructural analysis, Vickers microhardness tests and micro-adhesive and micro-abrasive wear resistance tests were performed. The layers produced exhibited a hardness close to 2250 HV and excellent wear resistance far superior to that of substrate.

Fully automated Vickers measurement systems with image analysis have been commonly used for over 20 years to measure case depth in carburizing, nitriding, and surface hardening processes. One of the most frequently discussed issues is the reproducibility of results both within individual systems and between different systems. This paper presents examples from industrial users to illustrate the ongoing challenges with these systems and the main points of discussion. The examples highlight the difficulties that arise even when systems operate within the accepted accuracy range of existing standards. Additionally, the paper will discuss future challenges and potential improvements for automatic hardness test systems.