Search results

Points out that the pitting resistance of welds in stainless steels is often inferior to the parent metals, and is an important factor to consider during the selection of materials of service in corrosive environments. Notes that an empirical pitting resistance equivalent (PRE), often expressed as PRE = % Cr + 3.3 × % Mo + 16 × % N, is used to rank different parent metals and that during welding, a number of metallurgical‐and surface‐related reactions take place locally, which make it impossible to predict the pitting corrosion resistance by a single expression. Reviews the effects of oxides, slag and other weld defects on the pitting resistance of welds in stainless steels, and highlights the importance of including the properties of fabricated areas into the life cycle cost (LCC) analyses.

Geigy Co. Ltd. Stand 75. Diversified application of benzotriazole as a corrosion inhibitor specifically for copper and its alloys is the main theme of Geigy's stand.

The principles of cleaning and sterilising of stainless steel plant and equipment are not always understood by those responsible for these operations with the result that corrosion of stainless steel can take place. However, if properly planned routines are followed, stainless steel should be virtually indestructible.

Aims to investigate the effect of chlorine on corrosion behaviours of stainless steels.

Very complicated thermodynamic calculations are needed to establish the E‐pH diagrams of commercial alloys, because they comprise of many elements. To avoid these complex calculations and facilitate corrosion prevention of AISI 316L stainless steel, the potentiodynamic method was used to construct the E‐pH diagram. The polarization curves were carefully experimented at the scan rate of 0.1 mV/s. The experimental conditions were aqueous solutions saturated with air (oxygen concentration 7.8‐8.5 ppm) containing chloride 0, 50, 500 and 5,000 ppm, pH 2, 4, 6, 8, 10 and 12, and at 25°C. The transpassive or pitting potential, the protection potential, the primary passive potential and the corrosion potential were determined from the polarization curves and plotted with respect to the pH of the solution. The ions in solution were investigated by qualitative chemical analysis and stated in the E‐pH diagrams.

The constructed E‐pH diagrams showed clearly the effect of chloride concentration in the tested conditions on the transpassive or pitting potential, the protection potential of AISI 316L stainless steels. The ion states after pitting corrosion were different at low and high pH. This may be useful information for further investigation of pitting corrosion mechanisms.

The E‐pH diagram was originally based on thermodynamic equilibrium. The potentiodynamic method was kinetically controlled and not in equilibrium. However, the experiments were kept at near stationary state as much as possible. The investigated E‐pH diagrams were limited for the solutions saturated with air containing chloride 0, 50, 500 and 5,000 ppm and at 25°C. The effects of temperature and other ions such as Fe³⁺, Mg²⁺, Ca²⁺, etc. on the transpassive or pitting potential, the protection potential, the primary passive potential and the corrosion potential should be further investigated, because natural water may contain those ions and is at high temperatures which could affect on the corrosion of AISI 316L stainless steels.

The investigated E‐pH diagrams may be applicable to avoid corrosion of AISI 316L stainless steels in similar conditions. The useful application may be for fields where natural water is not able to be treated, as is carried out in industry.

There have been several investigations on the effect of chloride on the corrosion behaviours of AISI 316L stainless steels. However, those investigations were carried out in different conditions. Very few experimental E‐pH diagrams of AISI 304L have been found, but not for AISI 316L stainless steels. The investigated diagrams showed also the ion states in pitting corrosion region which were influenced by pH. This may indicate the different pitting corrosion mechanism at different pH.

Under severely aggressive conditions, such as those experienced in the chemical industry, there has been extensive use of stainless steels in order to reduce corrosion losses. The successful industrial use of stainless steels led to requests for information on the corrosion resistance of stainless steels and similar alloys in sea‐water. This paper was awarded a prize in the Essay competition organised by the Corrosion Group of the Society of Chemical Industry, 1959.

Absolute cleanliness is synonymous with food and drink production. Plant components in contact with process liquors must conform to the highest possible standards of hygiene. All processing plants, whether they be simple one‐stage units or vast multi‐stage complexes, rely on pipework to convey the ingredients along their pre‐determined paths through the different stages of manufacture.

Table knives were one of the first products to be made in stainless steel. Just before the first world war Harry Brearley, who discovered that steel containing about 14% chromium and 0.3% carbon was highly resistant to corrosion and capable of being hardened, arranged for trial batches of stainless knives to be manufactured. Because this steel's corrosion resistance was greatly superior to that of ordinary steel, it became known as ‘stainless’ or ‘rustless,’ with the result that ever since that time cutlery users have felt defrauded if their ‘stainless’ knives have shown the slightest trace of corrosion under any circumstances. It is now known that under certain conditions the steel will corrode, therefore it is important for cutlers to ensure that their knives have the highest possible corrosion resistance to justify their description—‘stainless.’

The purpose of this paper is to verify the capability of pigmented coatings to mitigate the effects of thermal sensitisation of 430 stainless steel.

Experimental weld joints of non‐stabilised ferritic corrosion resistant steel type AISI 430 were prepared. Protective coatings in several variants were applied to a number of weldments, subsequently subject to corrosion tests in SO₂ and NaCl. The anticorrosive efficiency of the coatings was evaluated by means of normative visual assessment and metallographic analysis of the mechanism and depth of corrosion damage.

Anticorrosive efficiency of the tested coatings was experimentally established under conditions where differences were identified in structural changes caused by welding, or resulting from mechanical damage to the coating. Differences in the progress of corrosion damage caused by phase changes in the heat‐affected zone were established.

Tests of anticorrosive efficiency of coatings of selected types provided information about possible reduction in sensitisation of welded non‐stabilised steel. The effect of the investigated processes on degradation of anticorrosive resistance was identified.

A specific effect of phase changes accompanying welding on the corrosion mechanism was described and so were the reasons underlying development of corrosion damage at visually identical character of surface damage.

Introduction From the range of engineering materials, steel finds wide application in the building construction industry. The majority of steel used is for structural purposes but thinner gauge coil and sheet products in the form of coated mild steel or stainless steel are increasingly used for cladding and roofing.

BISRA's Corrosion Advice Bureau has been called upon to examine many corrosion failures and in this article, which is based on a lecture the authors gave to the British Association of Corrosion Engineers, North‐Eastern Section, a few of them are discussed in practical terms with particular reference to their underlying causes. The discussion is grouped under three headings: 1. Geometrical design. 2. Materials selection. 3. Protective coatings.