This is so, even for a matching nut and bolt Thanks to Luis Fernandes Silva for providing the sample. It is not possible to talk sensibly of corrosion resistance without reference to the specific environment that is to be resisted.Whilst it is true we might not see performance differences between commercial samples of 304 SS […]
A tale of poor materials quality control. I needed a couple of samples of 304 for the development work I was doing, so I cut them from the threaded end of the bolt illustrated below. It’s nothing special, just a random sample from my large collection of old, glue-in, machine bolts extracted from crags around […]
Thanks to Luis Fernandes Silva for providing the sample. Which is it, sulphide stress cracking (SSC) or chloride-induced stress corrosion cracking (SCC)? I raised this question in one of my earlier posts where I described the aggressive corrosion of stainless steel at Cabo da Roca. In that particular post I highlighted the main differences between […]
The title should be fair warning. This one is going to get geeky. If an anchor component is at all attracted to a strong magnet, don’t install it at a crag with a reputation for eating hardware. If you asked your supplier for 316, yet find the product is attracted to a strong magnet, don’t […]
Sulphide Stress Cracking The second part of a multi-part series In conducting this work I have been greatly assisted by Luis Fernandes Silva and Rui Rosado who have provided multiple samples and photos for analysis. Luis has spent a great deal of time measuring spot-sulphate levels, and the pH profiles of bolts he has extracted […]
The story of a sulphate crag The first part of a multi-part part series In conducting this work I have been greatly assisted by Luis Fernandes Silva and Rui Rosado who have provided multiple samples and photos for analysis. Luis has spent a great deal of time measuring spot-sulphate levels, and the pH profiles of […]
It’s not just the material you use, but critically, it matters how you use it. I have been researching the possibility that the brittle fractures we are seeing at Cabo da Roca and Sesimbra in Portugal are hydrogen embrittlement (HE) fractures mediated via the presence of sulphate reducing bacteria (SRB). Austenitic stainless steels like 304 […]
The benign cliffs of Campo Escola da Barra da Lagoa I reported wall-wash results from this low-corrosion crag some time ago. The sulphate levels were not elevated, a fact which supports my mantra “no sulphate – no corrosion”. However, it always interesting to take a somewhat deeper look, which I was able to do thanks […]
Home to some very corrosive sulphur crags. The Sintra volcanic complex, comprised mainly of granites and syenites, forms impressive, jagged sea cliffs that extend for several kilometres both north and south of the Cabo da Roca. Syenite is a low-silica form of granite, and looks very similar. Unlike typical granitic intrusions with their massive, sparsely-jointed […]
This note was posted to the Titanium Bolting FB Group 1st April 2020 Being locked down is not so bad if you can keep working in your lab. I’ve finally caught up with some wall-wash samples sent to me by Rodrigo Castelan Carlson from the beautiful granite slab sea cliffs of Campo Escola da Barra […]