The effect of tempering temperature on the microstructure and electrochemical properties of a 13 wt.% Cr-type martensitic stainless steel

Influence of tempering treatment on microstructure and pitting corrosion of 13 wt.% Cr martensitic stainless steel

Effects of pulsed Nd:YAG laser welding parameters and subsequent post-weld heat treatment on microstructure and hardness of AISI 420 stainless steel

Microstructure and room temperature strength of 9Cr–3W–3Co martensitic heat resistant steel after normalizing at 900–1200 °C for 1 h and then tempering at 750 °C for 1 h have been experimentally investigated using optical microscope (OM), field emission scanning electron microscope (FESEM), electron back-scattered diffraction (EBSD), field emission transmission electron microscope (FETEM) and tensile tests. The results show that with increasing normalizing temperature, the strength of the 9Cr–3W–3Co steel increases from 900 °C to 1000 °C, then keeps almost the same from 1000 °C to 1100 °C and finally increases again from 1100 °C to 1200 °C. The change in the room temperature strength can mainly be attributed to the change in precipitation strengthening. The size and the amount of particles after tempering are mainly due to the re-dissolution of particles during normalization. The higher the normalizing temperature is, the more the coarse particles formed during manufacturing will be re-dissolved, and then the larger the amount of fine particles precipitated during tempering is.

Effect of normalizing temperature on the strength of 9Cr–3W–3Co martensitic heat resistant steel

The application of additively manufactured (AM) stainless steel (SS) parts is rapidly emerging in a broad spectrum of industries. Laser powder bed fusion (LPBF) and direct laser deposition (DLD) are the main AM methods to fabricate a vast range of SSs like 316 L, AISI 420, 17-4 PH, 304 L, and AISI 4135. This article focuses on the corrosion performance of additively manufactured stainless steel parts made by LPBF and DLD. The passive film formation mechanisms and the corrosion performance of LPBF/DLD AM SS parts are discussed in comparison to their conventionally made counterparts. Microstructural features like porosity, inclusions, residual stress, surface roughness, elemental segregation, phases, and grain size distribution are elaborated thoroughly from the corrosion point of view, closely linked with the AM processing parameters. Generally, process parameters play an important role in the corrosion properties of AM parts by impacting the microstructural features. Assuming a proper set of parameters for the printing process, the overall corrosion performance of AM SS is better than its conventional counterparts. However, there are still controversies around some important aspects such as passive film structure, the nature of residual stress, post heat treatment processes, and grain size distribution and their impact on corrosion performance, which emphasizes the need for future studies in this area.

G. Borhani

Papers

The effect of heat treatment on mechanical properties and corrosion behavior of AISI420 martensitic stainless steel