Alloy Steel Sheets Research Articles

A Comprehensive Study of Oxide Layers Formed during the Elaboration of Low Alloy and Electrotechnical Steel Sheets

A Comprehensive Study of Oxide Layers Formed during the Elaboration of Low Alloy and Electrotechnical Steel Sheets

Depth profiling of organic coatings with GD-OES—investigation of molecular emission and interference

A low alloy steel sheet with a coating system incorporating an epoxy-based top coating Bonazinc™ is analysed with a DC glow discharge optical emission spectrometer system. The CCD type spectrometer records complete spectra in the range 160–460 nm. At a constant discharge power of 14 W, the discharge parameters were varied in three steps: 1000 V 14 mA, 700 V 20 mA, and 500 V 28 mA. Substantial molecular emission was observed in several parts of the spectrum, identified as originating from the diatomic molecules CH, OH, NH and probably CO. The observed molecular bands overlap several atomic emission lines, causing line interference at these spectral positions. The most intense molecular emission was observed at the condition 1000 V 14 mA, corresponding to the lowest pressure and highest plasma impedance. The results also show that the highest signal to background, in the Bonazinc™ coating, for atomic emission lines is obtained at high pressure–low impedance discharge conditions.

Improving the analysis of small precipitates in HSLA steels using a plasma cleaner and ELNES

The change from producing high strength low alloy (HSLA) steel sheet by conventional thick slab casting to producing it by direct charged thin slab casting causes a major change in the evolution of the precipitation. A key area of interest is the composition of the sub- 10 nm precipitates used to produce dispersion hardening. Carbon extraction replicas are frequently used to study precipitates in steels and other metals. When used with annular dark field imaging, this technique gives high contrast images of the precipitates while the thin carbon film adds little background or additional characteristic signals to either electron energy loss spectra or energy dispersive X-ray spectra. The method has the additional major advantage of removing the ferromagnetic matrix when studying HSLA steels. However, when the precipitates contain carbon, the C K-edge is dominated by the contribution from the amorphous carbon film. A plasma cleaner can be used to thin this carbon film to ∼0.5 nm or less and then the contribution from the carbon in the precipitate can be separated from that in the carbon film using the electron energy loss near edge structure. A similar approach can be taken to separate the oxygen content of the precipitate from that of oxides formed from low-level impurities in the amorphous carbon during the plasma thinning process. In most cases, the precipitate studied here contained little or no oxygen even for the smallest sizes examined (∼4 nm ). The precipitates contain mainly nitrogen with little carbon. For some compositions, the precipitates are clearly sub-stoichiometric.

Hot roll bonding of Al–Pb-bearing alloy strips and steel sheets using an aluminized interlayer

This article describes a study of the application of a hot roll bonding technique to Al–Pb-bearing alloy strips and steel sheets using an aluminized interlayer. It was found that the overall bond between these two metals resulted from two different types of bonds: a “block” bond, linking the Al–Pb alloy strips and aluminum topcoat layer to the Fe–Al intermetallic compound, and a “blank” bond, linking the Al–Pb alloy strips and aluminum topcoat layer to the bare steel surface in the area where the block has separated from the steel substrate. The study investigated the effects of dipping time on the thickness of the intermetallic layers and of the area fraction of blank bond on the bond strength. The overall bond strength depends mainly on the strength and the area fraction of the blank bond. A linear relationship exists between the overall bond strength and the area fraction of blank bond. The bond strength of the blank bond is four times greater than that of the block bond. The area fraction of the blank bond increases with increasing intermetallic thickness up to a thickness of 73 μm, but thereafter decreases due to the rotation of the intermetallic blocks.

Production method on pipe of thin-spring steel sheet

In plastic working, the research away from the forming of carbon steel sheet in favor of alloy steel sheet is going into high gear. Especially, since products formed by thin-alloy steel sheet can get the equivalent strength to that of thick-carbon steel sheet, it is very useful to reduce the weight of industrial structure and so on. However, on the other hand, it is very difficult to form alloy steel sheet because these materials are of low elongation, high yield, and tensile strength. This paper deals with the production process on cold roll forming that takes advantage of the nature of spring-back of spring steel sheet to make the special pipe. The special pipe is very convenient to transfer because the pipe can wind up like the coil steel sheet [JIS Handbook Steel, 1998; J. JSTP 38 (12) (1997) 443; J. JSTP 38 (12) (1997) 443; JSME Int. J. 1 (2) (1990) 33].

Acoustical Society of America Meeting

In this study, the relations between interfacial microstructure and mechanical behavior of aluminum alloy sheets and zinc-coated steel sheets magnetic pulse welding (MPW) joints were characterized systematically. MPW joints of aluminum alloy and ungalvanized steel sheets were prepared for comparative analysis. Results showed that some of zinc layer on the galvanized steel was washed away to form metal jet under the high-speed collision. The change of failure mode from interfacial failure to base material fracture due to interfacial microstructure evolution was the fundamental reason for different mechanical behavior of two MPW joints. Because of the difference in element content and the severe plastic shear at the interface, the crystalline grain morphologies and sizes of aluminum and zinc in the transition zone changed. Amorphous structure was also found in the transition zone. The existence of the zinc layer would form brittle and hard phases on the interface, resulting in the generation of welding defects, thereby reducing mechanical properties of the joint.

Zn-Fe 系めっき層の分極・溶解挙動と定量分析への応用

Electrochemical and chemical dissolution behavior of Zn-Fe alloy coatings and steel sheets was investigated, and following two methods for selective dissolution of Zn-Fe alloy coatings from steel sheets were developed.(1) Alkali-dissolution method : In a strong alkaline solution (NaOH-triethanolamine (TEA)-H2O), Zn-Fe coatings are dissolved taking the form of ZnO22- and [Fe(OH)4·TEA]-, while steel sheets and Fe-Zn (Fe-P) coatings are insolble because passive films are formed on the surface.(2) Cathodic polarization electrolysis method : Under cathodic polarization (-1.2 Vvs. SCE) in a NH4NO3 electrolyte (NH4NO3-1, 10-phenanthroline (ο-phen)-MeOH-H2O (pH=10 adjusted by NH4OH)), Zn-Fe and Fe-Zn (Fe-P) coatings are dissolved taking the form of [Zn(NH3)4]2+ and [Fe-(ο-phen)3]2+. At this potential, dissolution of steel sheet is prevented by the ο-phen films adsorbed on the steel surface.Alkali-dissolution method is applicable to quantitative analysis of Zn-rich Zn-Fe layer (Fe<40%) coatings and upper/down layer of Fe-Zn (Fe-P)/Zn-Fe double layer coatings.Cathodic polarization electrolysis method is applicable to quantitative analysis of Fe-rich Zn-Fe layer (Fe<70%) coatings.

Tension–tension fatigue crack, propagation in high strength, low alloy steel sheets

AbstractA study was undertaken of tension–tension, fatigue crack propagation of two high strength, low alloy steel (S3 and S4) sheets at mean and maximum stresses of 30 and 55% of their tensile strengths, respectively, and results were compared with those from a hot rolled, low carbon steel (S1). The maximum life in terms of number of cycles to fracture was shown by steel S1, while S4, with a bainitic microstructure, showed the minimum. The S3 steel, with a ferrite–pearlite microstructure, showed a fatigue life between the other two. These results are in accordance with the tensile strength/yield strength ratios of the alloys. Further work on S4 steel was carried out in greater detail and tensile to shear transition behaviour of the fatigue crack front was observed. Correlations were established between microstructure, stress intensity, and the rate of crack propagation. The commencement of shear lip development in the bainitic steel was found to be independent of the sheet thickness, but dependent upon t...

Tension–tension fatigue crack, propagation in high strength, low alloy steel sheets

Tension–tension fatigue crack, propagation in high strength, low alloy steel sheets

ジンクリッチプライマー鋼板のプレス成形性に与える塗膜因子の影響

A zinc-rich primer painted steel sheet for automobile body has much zinc powder in paint film for the purpose of doing spot welding. A paint film which has a large quantity of pigment is brittle and susceptible to flaking by press forming, and its corrosion resistance becomes poor. Some paint film factors influencing its flaking by press forming were studied. (1) By the addition of lubricant (ex. MoS2) to paint film, the flaking of the paint film is reduced. The effect of the lubricant addition is due to the reduction of the friction coefficient of paint film. As an other effect the lubricant is coated on the die, and good lubrication appears.(2) Generally, zinc powder content of zinc-rich primer paint film is about 90 wt%. By decreasing zinc powder content of paint film, the flaking of paint film is reduced. As the paint film becomes thicker, the shear stress on it decreases and flaking of the paint film is reduced.(3) The flaking of paint film on electroplated Ni-Zn alloy steel sheet is less than that on cold rolled one.

The strength and toughness of dynamically strain aged alloy steel sheets

The response of alloy steels to dynamic strain aging (straining (about 2%) at relatively low temperatures) in both the quenched and tempered and ausformed conditions was investigated. Strength, ductility, and toughness were measured as a function of straining and tempering temperatures. Structural observations were made on the strained and unstrained steels. By appropriate choice of strain and tempering temperatures, the strength of both the quenched and tempered and the ausform steels was increased by about 40,000 psi. In the ausform steels, yield strengths of 270, 000 psi were achieved by dynamic strain aging with a reliability ratio (Kc/oys) of one. Since the slope of Kc/oys vs. oys is small, it is suggested that this process may be used to attain yield strengths of 300,000 psi is steels with exceptional toughness.

Use of sprays for quenching low alloyed steel

1. Water-air mixtures in which 3 m3/m2·h of water is used do not produce the cooling rate necessary for increasing the hardness of low alloyed steel sheets 12 mm thick or thicker. 2. Quenching with a spray makes it possible to regulate the cooling rate and the degree of hardening of low alloyed steel. 3. Quenching by sprays is the most effective for sheets 15–25 mm thick.

A low alloy sheet steel with improved strength

A low alloy sheet steel with improved strength

The Bearing Strength of Steel and Aluminum Alloy Sheet in Riveted or Bolted Joints

T object of this investigation was to develop ''tear-out design criteria by means of which the strength of the material outside the bolt or rivet in a joint in tension could be more accurately determined. As test data were obtained and studied it became apparent that the edge distance had a definite relationship with the bearing strength and the test program accordingly was arranged to show how the bearing strength varies with the edge distance, with bolt or rivet size and with sheet thickness. A number of typical test specimens are shown in Fig. 1. In all cases the specimen was made of two pieces of 24ST aluminum alloy or chrome-molybdenum steel sheet fastened together with a single bolt or rivet. The bolts were of steel heat-treated to an ultimate tensile strength of 125,000 lbs. per sq.in. and were used in all cases in double shear. The rivets were made from 17S aluminum-alloy rivet wire purchased under Army-Navy specifications and heat treated in a nitrate bath to an ultimate tensile strength of 55,000 lbs. per sq.in. They were used in all specimens in single shear. All specimens were tested in tension to failure. Most of the specimens were formed with square ends. A few, however, were made with rounded ends. Of the latter specimens some had the bolt hole drilled concentric with the rounded end, some had the hole drilled with a plus offset and some with a minus offset, noted in the presentation of the test results. To clarify the offset designations it may be stated that when the distance from the center of the hole to the end of the lug was less than the radius of curvature of the rounded end, the offset was assumed to be minus. The sheet stock used in these tests was purchased under Army-Navy specifications. Test coupons were cut from the 24ST material and showed an ultimate tensile strength that varied from 68,100 to 73,700 and averaged 71,000 lbs. per sq.in. The bearing values obtained in the tests were not corrected to a common ultimate strength. In the case of the chrome-molybdenum steel specimens tested in the as received condition, the test coupons showed a variation in ultimate strength of 71,800 to 83,500 lbs. per sq.in. The