Tin-free Steel Research Articles

Pitting Corrosion of the Aluminum Ends of Tin-Free Steel Cans

Abstract Bimetal cans, in which the body is made of tin-free steel (TFS) with easy-open ends of aluminum alloy, may be used to hold ion-supplementing drinks, juice, and the like. In such cases, the rest potential of the TFS in the contents of the can may be more noble than the pitting potential of the aluminum alloy, resulting in galvanic corrosion of the Al-alloy ends. Accordingly, studies were carried out on two methods of preventing such corrosion: (1) development of Al alloys having a higher (more noble) pitting potential, and (2) a technique for cladding with a sacrificially anodic material. Furthermore, in order to develop an aluminum alloy for the can ends that is resistant to pitting corrosion (i.e., has a more noble pitting potential), the Cu2+ ion method for rapidly measuring the pitting potential of the aluminum alloy has been developed and is being used to investigate the effects of various additive elements. This method has made it possible to develop an Al-Si-Cu-Mn alloy in which pitting cor...

Progress in materials for can stock and future trends.

Developments in electrolytic tin plate, tin-free steel and more recent low tin materials are described with emphasis on their corrosion performance and their applicability to the newer can manufacturing processes. The significance of tinplate special property tests and their relative importance are discussed as related to corrosion performance in cans for moderate to high corrosivity food products. Information regarding pitting corrosion of aluminum killed continuous cast tinplate in cans for light colored fruits is also reviewed. Tin-free and low tin materials are being used in drawn and welded cans, but better enamel coverage is required than for tinplate cans. Long term trends show that aluminum has taken over most of the beer and soft drink market but its use in food cans remains very limited. New processable multilayer plastic barrier materials have been introduced as cans, bowls and trays for single serving microwaveable foods, which could have a significant impact on metal cans. The solid waste issue and recyclability of the various materials is discussed. A new process for improving the quality of shelf stable processed foods is also described.

顕微エリプソメトリーによるＴＦＳ水和酸化クロム皮膜の解析

A technique of microscopic ellipsometry that measures a thickness of thin film on microareas of about 10μm∅ diameter has been developed. Application of this technique to analyze the thickness distribution of hydrated chromium oxide film on various kinds of Tin Free Steel (TFS) has shown that there are extensive differences in the uniformity of the film. It was also found that there is a good correspondence between the thickness distribution and the bond durability of side-seam cans made of TFS in retort treatment. Bond durability of TFS is already known to be affected by chromium oxide composition, including sulphate impurity and the degree of hydration. This study has revealed that the uniformity of oxide film layer is an another important factor of the bond durability of TFS.

On-Line Thickness Meter for Extra Thin Film

An advanced on-line thickness meter for transparent and extra thin film has been developed based on a spectral analysis method. This is applicable for measuring the hydrated chromium oxide layer of about 5 to 25 nm in thickness on Tin Free Steel. The main features of this thickness meter are mainly the use of ultraviolet wavelengths, and a very simple and devised structure. Moreover, it has good accuracy and stability against various kinds of disturbances which occur at on-line measurelent. The thickness meter is also available for the measurement of other transparent thin films.

Adhesion of Biaxially Oriented Polyethylene Terephthalate Film to Tin Free Steel

Adhesion of Biaxially Oriented Polyethylene Terephthalate Film to Tin Free Steel

溶接性に及ぼす材料の表面形態と溶接法の影響

An evaluation of weldability has been made on new materials used for welded cans.And the relation between the electric contact resistance(Rc) and, the surface characteristics of these materials has been studied.Furthermore the possibility of welding of tin free steel by improving the surface characteristics and the welding method has been also discussed.The results obtained were summarized as follows :(1) A lightly tin coated steel with the nickel preplated layer, when the nodular metallic tin layer was formed, had a low Rc and a good weldability.(2) A tin free steel, when the granular metallic chromium layer was deposited, showed the lower Rcand the better weldability than the tin free steel which has flat metallic chromium layer.(3) The improved welding method, which applies pre-pressing on the blank edge before seam welding or uses tin coated copper wire for intermediate electrodes, also showed lower Rc and raised weldability.

二軸配向ポリエチレンテレフタレートフィルムのティン・フリー・スチールへの接着

二軸配向ポリエチレンテレフタレートフィルムのティン・フリー・スチールへの接着

ティンフリースチールの耐レトルト処理性に及ぼす逆電解処理の影響

ティンフリースチールの耐レトルト処理性に及ぼす逆電解処理の影響

High Vacuum Flame Sterilized Fruits: Influence of Can Type on Storage Stability of Vacuum Packed Peach and Pear Slices

The feasibility of using enameled tin and tin-free steel (TFS) cans for processing oxygen sensitive fruits by high vacuum flame sterilization was evaluated. Through 18 months storage at ambient temperatures, the appearance and quality of the HVFS peaches and pears remained acceptable for all can types. Fruits packed into plain tin cans appeared brighter and tasted tangier than those packed into TFS or inside-enameled tin cans. Texture, pH and titratable acidity of fruit were not measurably affected by variation in can types. Mechanical deaeration followed by flame sterilization, produced a product with quality comparable to that achieved in flame deaerated packs.

オンライン・クロム水和酸化物膜厚計の開発

オンライン・クロム水和酸化物膜厚計の開発

New materials for food packaging—The future

It is unlikely that there will be many new materials used in future food packaging, but there will be new combinations of materials and new uses to which they are put. Changes in relative costs may reverse certain trends. Developments in the following areas are covered: metals, such as tin-free steel and the combination of aluminium and plastics; paperboard, such as tubs and ovenable board; glass, such as ‘Plastishield’, and plastics, themselves, dealing with developments in processing, such as stretch blow moulding and solid phase pressure forming. Developments in the newer materials such as poly(ethylene phthalate), the nitriles, poly(vinyl alcohol) and ethylene/vinyl alcohol copolymer and polycarbonate, are also considered.

最近の表面分析機器による表面解析と表面改善 (II)

This article reviews the application of surface analytical techniques by which convenient information has been obtained on the surface layer of container materials. Included are the application for tinplate, TFS (Tin free steel) and Aluminum. By use of these techniques, the thickness and the composition of the surface layer, which significantly affect the corrosion resistance and lacquer adhesion, can be determined and provide us with some aspects to improve the performance.The corrosion resistance of tinplate depends on the surface nature of steel substrate. The surface enriched constituents, which could not be completely removed in the preparation section of electrolytic tinning line, act to turnish the apearence and also result in high ISV (Iron solution) and ATC (Alloy-tin couple) value. Concerning the passivation film on tinplate, the thickness and composition of surface oxide film have a correlation to the lacquer adhesion. The nature of hydrated chromic oxide on TFS, which correlates to the deterioration of lacquer adhesion in a hot citric acid solution, has also been proposed from a new aspect. Analysis of the stained layer on aluminum reveals that the layer is contaminated by iron and other elements originated from city water and that iron plays an important role in staining.

極薄すずめっき鋼板

This report shows the results of weldability, contact resistance, rust resistance, corrosion behavior and lacquer adhesion on the Lightly Tin Coated Steel (LTS) having 0.3 and 0.6g/m2 of tin compared with tinplate having 1.28g/m2 of tin and Tin Free Steel. Preliminary test on the iron-tin alloy composition of heavily coated tinplate indicated that at 220°C-380°C, iron-tin alloys were almost FeSn2 and there were some differences in shape and size of the alloy. Weldability at the welding speed of 30m/min and 48m/min was improved with increase of tin coating weight; Available current range of reflowed 0.3g/m2 LTS was less than 100A at 30m/min, but that of non-reflowed 0.6g/m2 LTS reached 190A which would be sufficient for commercial welding at 30m/min. Contact resistance of 0.6g/m2 LTS was almost similar to that of tinplate, however fully alloyed LTS had relatively high resitance. Polarization characteristics of iron, tin, iron-tin alloy and metallic chromium indicated that in tomato juice, corrosion behavior of LTS was similar to that of tinplate, however underfilm corrosion of LTS was less than that of tinplate and iron pick up tendency of LTS was also less than TFS. Lacquer adhesion of fully alloyed LTS was better than that of tinplate and other LTS.

Energy and raw materials requirements for tinplate production in the U.K.

This paper calculates the energy and raw materials required to produce tinplate and tin-free steel in the United Kingdom in 1978/79. The production sequence is traced from raw materials in the ground through to finished sheet. The gross energy requirement for the production of tinplate is shown to be 49.79 MJ/kg and that for tin-free steel is 42.86 MJ/kg. A detailed breakdown by fuel type and contributing operation is given and the calculations are based almost entirely on data collected directly from the relevant industries. The results are compared briefly with past performance and with present European practice.

ＴＦＳクロム水和酸化物皮膜の加熱による構造変化

The structure of hydrated chromium oxide on Tin Free Steel (TFS) formed in a low concentration CrO3 bath containing a small amount of fluoride, silicofluoride or sulfate was investigated by XPS. Lacquer adhesion before and after immersing in a hot citric acid solution was also examined. The lacquer adhesion of TFS was discussed based on the structure of hydrated chromium oxide. The results obtained were as follows: 1) The hydrated chromium oxide films on TFS basically consisted of polymerized chromium (III) hydroxide, in which a part of OH ions was replaced by fluoride ions or sulfate ions. In the case of silicofluoride bath, silicon was not incorporated into the film. 2) When the films formed in the fluoride baths were heated at a lacquer curing temperature, both the oxolation of hydrated chromium oxide and the removal of incorporated fluorine occurred. On the other hand, in the case of the film formed in the sulfate bath, incorporated sulfate ions were kept in the film after heating, and the oxolation of hydrated chromium oxide occurred slightly. 3) After immersing in a hot citric acid solution, TFS formed in the fluoride baths showed much better lacquer adhesion than TFS formed in the sulfate bath. This was explained by considering larger amount of hydroxyl ions in the films formed in the fluoride baths, when assuming that the adhesion is supported by hydrogen bonding between the hydroxyl ions and the lacquer. 4) After immersion in a hot citric acid solution TFS heated before lacquer coating showed lower adhesive force than TFS without heating because of the slight oxolation of hydroxyl bridges in films on TFS.

TFSの皮膜特性について

TFSの皮膜特性について

On-Line System for Measuring Thickness of Ultra-Thin Non-Metallic Layer on Strip Surface

Nippon Steel Corporation has developed an advanced instrumentation for automatic coating control at Yawata Works. It is designed primarily for measuring the thickness of ultra-thin oil layer or hydrated chromium oxide layer on electroplated steel strip for can-making. These layers have thicknesses ranging from 2 to 20 nm, small mass and transparent or translucent appearance.Based on the principle of ellipsometry, the new film thickness measuring system is already in service on processing lines at NSC.It has a measuring accuracy of 0.015 g/BB for oil film on electrolytic tin plate in the coating weight range of 0.10 to 0.30 g/BB and 1.3 mg/m2 for hydrated chromium oxide film on tin-free steel in the coating weight range of 5 to 25 mg/m2.

Tin Free Steelにおけるクロム水和酸化物皮膜の構造について

Tin Free Steelにおけるクロム水和酸化物皮膜の構造について

偏光解析法によるTin Free Steelのクロム水和酸化物皮膜の厚さ測定について

偏光解析法によるTin Free Steelのクロム水和酸化物皮膜の厚さ測定について

Tin Free Steelにおけるクロム水和酸化物皮膜の脱水現象について

The hydrated chromium oxide film on the chromium-plated type Tin Free Steel was investigated by means of a micro-thermobalance, a T.O.F. mass-spectrometer, thermal decomposition gas-chromatograpy and an infrared-spectrometer.The results obtained are as follows:(1) The water in the film vaporizes up to 240°C and the amount of H2O was estimated as 24 per cent.(2) The infrared absorption spectra of the film are found at 3400 cm−1 due to OH stretching vibration and 1600 cm−1 due to HOH bending vibration. These absorptions increase with the film thickness and decrease by heating.(3) From the surface observation by means of a scanning-type electron microscope, it is found that some cracks are formed in the thick film by heating.From the above results, it may be concluded that the behavior of the water in the film is analogous to that in the passivated film on steel or stainless steel, and the dehydration of the film affects the paintability and corrosion of the substrate.