Iron & Steel Society of Iran International Journal of Iron & Steel Society of Iran 2981-0388 3 1 2006 06 01 The Strain Dependence of Post-Deformation Softening during the Hot Deformation of 304H Stainless Steel The Strain Dependence of Post-Deformation Softening during the Hot Deformation of 304H Stainless Steel 1 7 4805 EN A. Najafizadeh Department of Materials Engineering, Isfahan University of Technology, Isfahan, Iran J. J. Jonas Department of Metallurgical Engineering McGill University, Montréal, Canada Journal Article 2006 08 06 Experiments were carried out in which the dependence of the fractional softening on temperature, time and strain rate was determined in a 304H stainless steel. Three prestrain ranges were identified pertaining to three different post-deformation softening behaviors: 1) prestraining to below the DRX critical strain: strongly strain dependent softening by SRX alone with softening kinetics controlled by growth rate of the nuclei; 2) prestraining to above the DRX critical strain: SRX + MDRX softening with weaker strain dependence of the kinetics but still controlled by grain growth; 3) at a prestrain of e* and beyond: nucleation-controlled MDRX softening with the full inhibition of SRX. The transition prestrain e* can exceed the peak strain if the DRX grain refinement ratio g= D0/DDRX > 4. The transition to MDRX-dominated softening can be attributed to a constant value of the normalized strain hardening rate independent of the preloading temperature and strain rate. The softening data from the compression tests show that at e*, the time for half softening t50 exhibits a minimum. These data differ somewhat from observations obtained in the torsion testing of solid bars, in which no strain dependence of t50 was detected at e* and beyond. Whether or not the strain dependence of t50 vanishes in the MDRX range is sensitive to the test method employed to study the post-deformation softening.

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Iron & Steel Society of Iran International Journal of Iron & Steel Society of Iran 2981-0388 3 1 2006 06 01 Dynamic Recrystallization under Hot Deformation of a PH Stainless Steel Dynamic Recrystallization under Hot Deformation of a PH Stainless Steel 8 12 4806 EN A. Shokuhfar Faculty of Mechanical Engineering, Khajenasir Toosi University of Technology, Tehran, Iran S. M. Abbasi Faculty of Mechanical Engineering, Khajenasir Toosi University of Technology, Tehran, Iran N. Ehseni Faculty of Material Engineering, MUT, Tehran, Iran Journal Article 2006 06 19 Dynamic recrystallization, DRX, behaviour of a precipitation hardened, PH, stainless steel was studied in connection with microstructural developments in a compression test. The experimental results showed that the dominant mechanism of softening is DRX, but at high strain rates and low temperatures, ie, high Zener-Holman parameter, Z, work hardening and dynamic recovery, DRV, produced a pancked structure. When Z values decreased, the flow curves displayed DRX in two ways: single peak behavior observed at low Z values and multiple peak behavior at the lowest ones. In addition, the peak strain, εp, necessary for DRX is also determined as a function of peak stress, sp, and Z. According to the observed and calculated data, at low sp values, εp is directly proportional to sp, while in higher amounts, εp rarely depends on it. Besides, εp expotenentially depends on Z. https://journal.issiran.com/article_4806_1cc8a8ea51cd0adddf5dab504a285915.pdf

Iron & Steel Society of Iran International Journal of Iron & Steel Society of Iran 2981-0388 3 1 2006 06 01 Niobium Alloyed High Strength Steels for Automotive Applications Niobium Alloyed High Strength Steels for Automotive Applications 13 19 4807 EN Hardy Mohrbacher Niobium Products Company GmbH, Steinstrasse 28, 40210 Düsseldorf, Germany Journal Article 2005 11 22 Modern vehicle bodies make intensive use of high strength steel grades to meet the contradicting demand of lighter weight and simultaneously better mechanical performance. For many steel grades microalloying by niobium is the key to achieve their characteristic property profile. In HSLA steels niobium enhances the strength primarily by grain refinement. In interstitial free high strength steels niobium serves as a stabilizing element. Some modern multiphase steels rely on niobium to achieve additional strength via grain refinement and precipitation hardening. Microstructural control constitutes a powerful means to further optimize properties relevant to automotive processing such as cutting and forming. The role of niobium microalloying in that respect will be outlined.

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Iron & Steel Society of Iran International Journal of Iron & Steel Society of Iran 2981-0388 3 1 2006 06 01 Stress- Corrosion Crack Initiation of High-strength Pipeline Steel in Near-neutral pH Environments Stress- Corrosion Crack Initiation of High-strength Pipeline Steel in Near-neutral pH Environments 20 25 4808 EN B. Fang Environmental Corrosion Center, Institute of Metal Research Chinese Academy of Science, Shenyang, P. R. China, 10016 and CANMET Materials Technology Laboratory 568 Booth Street, Ottawa, Ontario, Canada K1A 0G1 E-H. Han Environmental Corrosion Center, Institute of Metal Research Chinese Academy of Sciences, Shenyang, P. R. China, 10016 M. Elboujdaini Environmental Corrosion Center, Institute of Metal Research Chinese Academy of Sciences, Shenyang, P. R. China, 10016 W. Zheng CANMET Materials Technology Laboratory 568 Booth Street, Ottawa, Ontario, Canada K1A 0G1 J. Li CANMET Materials Technology Laboratory 568 Booth Street, Ottawa, Ontario, Canada K1A 0G1 R. W. Revie CANMET Materials Technology Laboratory 568 Booth Street, Ottawa, Ontario, Canada K1A 0G1 Journal Article 2006 06 20 Stress-corrosion cracking (SCC) tests were conducted in the near-neutral pH standard solution, NS4, and in an actual soil solution, using four-point bending at a high stress ratio and low frequency conditions very similar to those of operational pipelines. Pitting incubation appeared first and then pitting initiated and grew in both solutions although there were many more pits on the specimen tested in soil purged with 5% CO2 +95%N2 than in the specimen tested in NS4 solution purged with the same gas. These observations show that samples in soil solution are more susceptible to pitting than those in NS4 solution. When the pit reached a critical size, the increased stress concentration around the pits, resulted in transition to a crack.

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Iron & Steel Society of Iran International Journal of Iron & Steel Society of Iran 2981-0388 3 1 2006 06 01 Simulation of Temperature Distribution in Hot Strip over Transfer Table Simulation of Temperature Distribution in Hot Strip over Transfer Table 26 32 4809 EN A. Saboonchi Department of Mechanical Engineering, Isfahan University of Technology, Isfahan, Iran N. Mansouri Department of Mechanical Engineering, Isfahan University of Technology, Isfahan, Iran Journal Article 2006 03 11 Transfer table is an essential stage between roughing and finishing rolling stands in a hot-strip rolling mill. High temperature and long time that strip is exposed to air at this stage cause a considerable heat loss that accounts for uneven temperature distribution, non-uniform surfaces, reduced product quality and increased production costs. Using thermal shields on the transfer table is considered an efficient means of reducing energy consumption and of improving product quality. In this paper, temperature distribution and heat loss from the strip is investigated while passing through transfer table in the hot-rolling at Mobarakeh Steel Complex (MSC),Isfahan,Iran. Three cases are considered; namely, in the absence of thermal shield, in the presence of thermal shield, and with both thermal shield and heat source. The results obtained from the numerical solution indicate that the case with both thermal shield and heat source on the transfer table has the most favorable effect on reducing heat losses and even temperature distribution in the strip.

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Iron & Steel Society of Iran International Journal of Iron & Steel Society of Iran 2981-0388 3 1 2006 06 01 Analyzing the Failure of Master Mould in Casting of Copper Anode Moulds and Suggesting a more Suitable Metal Mould Analyzing the Failure of Master Mould in Casting of Copper Anode Moulds and Suggesting a more Suitable Metal Mould 33 42 4810 EN M. Adjabshiri Materials Science and Engineering Department – Shahid-Bahonar University of Kerman, Iran S. Sharafi Materials Science and Engineering Department – Shahid-Bahonar University of Kerman, Iran Journal Article 2006 07 22 Master moulds are used to cast copper anode moulds. These iron moulds are made of grey or nodular cast irons. According to desirable properties of ductile irons, it was expected that ductile cast iron moulds could have performed their nominal life. But in service, these moulds have not performed their nominal life and they have experienced premature failures due to warping and cracking. Also grey cast iron moulds fail because of generalized surface cracks. In this paper, the failure of master moulds is investigated according to the metallographic and hardness measurement tests. Then pearlitic and austempered ductile iron alloys are proposed and tested through short time high temperature tensile and thermal shock tests with respect to working conditions of the moulds. Also master mould is modeled by Finite Element Method to evaluate the thermal conditions. Finally it is concluded that compared with pearlitic ductile iron, austempered ductile iron has higher resistance to thermal shock.

https://journal.issiran.com/article_4810_b112ca4087d668785e947a57493d1740.pdf