THE EFFECT OF ANNEALING ON MICROSTRUCTURE OF STEEL NITRONIC 60
Nitronic 60 (UNS S21800) is a highly alloyed austenitic stainless steel with the increased content of manganese and silicon which has good mechanical and corrosion properties at high temperatures and loads. This paper presents the results of investigations of the influence of annealing process on the microstructure of steel Nitronic 60. Heat treatment consisted of annealing from 400 to 850 0 C for four hours followed by cooling in the water. The light and scanning electron microscope (with EDS analysis) were used for microstructure analysis. Analysis showed presence of sigma phase at higher temperatures. The sigma phase was precipited mainly at the austenite grain boundaries, δ/γ interface boundary and δ ferrite phase. Hardness testing showed increasing of hardness with precipitation of sigma phase.
Corrosion of austenitic stainless steels : mechanism, mitigation and monitoring
Introduction to austenitic stainless steels Uniform corrosion of austenitic stainless steels Pitting corrosion Crevice corrosion Sensitization and testing for intergranular corrosion Metallurgical influences on stress corrosion cracking Stress corrosion cracking of austenitic stainless steel weldments Applications of fracture mechanics in stress corrosion cracking and introduction to life prediction approaches Microbiologically influenced corrosion Corrosion of austenitic stainless steel in liquid sodium High temperature corrosion of austenitic stainless steel Corrosion detection and monitoring in austenitic stainless steels using non-destructive testing and evaluation techniques Corrosion related failures of austenitic stainless steel components Surface modification for corrosion protection of austenitic stainless steels General guidelines for corrosion control.
Failure analysis for poor solderability of Au surface of PCB
Nonwetting is one of the common problems and is always rejected in electronic assemblies. ENIG pads of a PCBA exhibited nonwetting after lead-free reflow soldering. With the aid of stereomicroscope, SEM&EDS and XRF, a series of analysis was performed. And after visual inspection, surface and cross section analysis, thickness measurement and solderability test, it can be inferred that oxidation of plating surface was the main reason for nonwetting, and corrosion in Ni plating caused an adverse impact on solderalibity.