The Gleeble at the University of Wollongong and Bluescope Steel
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The ® Dynamic Systems Inc. Gleeble Tel: 518 283-5350 Fax: 518 283-3160 NEWSLETTER Internet: www.gleeble.com Email: [email protected] Summer 2011 Gleeble Application Story Come See Us at the Shows The Gleeble at the University of Recap: Gleeble User Workshop India (GUWI) Wollongong and BlueScope Steel The BlueScope Steel Metallurgy arena. In this capacity it provides opportu- The 3rd Gleeble User Workshop Centre, University of Wollongong was nities for academic staff to play a greater and National Conference on Thermo- established in 1995, consolidating a part in supporting the local steel industry Mechanical Simulation using Gleeble long history of collaboration between and for technologists from industry to Systems was held September 16–18, the University and BlueScope Steel. It contribute to academic development. It 2011 at JSW Steel Ltd., Vidyanagar, undertakes strategic, basic and applied also gives students access to industry, as Near Bellary, Karnatata State, India. research that complements the in-house well as giving them advanced educational Building on the success of the ear- research capacity of BlueScope Steel and opportunities in steel products and pro- lier two Gleeble User Workshop and provides related undergraduate and post- cesses. Since 1997 the Centre has con- Conferences that were held in 2008 graduate education. Operating funds are ducted research on numerous competitive and 2010, the conference featured shared between UOW, BlueScope Steel grant projects with a total budget of nearly well-known researchers and speak- and the Federal Government’s Australian $10 million. ers from manufacturing, industry and Research Council (ARC) through compet- Research activities are conducted in research institutes. itive research grants. BlueScope Steel is a several key areas focusing on the chang- Topics included: global steel producer and the leading steel ing needs of BlueScope Steel as the com- • Continuous casting company in Australia and New Zealand. pany has responded to changes in its com- • Rolling and forging The Centre focuses on research out- mercial environment. The Pyrometallurgy • Welding comes, development of research capacity, Research Group focuses on iron and steel • Strip annealing and the fostering of an awareness of steel making processes, and on sustainable • New applications and innova- research in the national and international Continued on Page 4 tions • Challenges in Gleeble testing and solutions For additional information, please contact Mr. Suyash Nadkarni at [email protected] 1st Workshop on Gleeble Welding Process Simulation & Gleeble Welding Group Meeting Gleeble Welding Group Workshop and Meeting will be held Feb. 27–28, 2012 in Graz, Austria. It will focus on the exchange of information about experiments related to welding pro- cesses carried out with any Gleeble machine. Continued on Page 3 The busy Gleeble laboratory at the BlueScope Steel Metallurgy Centre, University of Wollongong. Recent Gleeble Papers 476 grain structures primarily using a sever- the welding behavior of this alloy has plastic-deformation method, such as equal been evaluated, and it has been shown The Mechanism of Brittle Fracture channel angular pressing (ECAP), 3D that a softened region in the heat-affected in a Microalloyed Steel: Part I. forging, torsion straining with or without zone (HAZ) is a principal feature of the Inclusion-Induced Cleavage applying axial pressure, and accumulative weld zone. A model of this softening, by D.P. Fairchild, D.G. Howden, roll bonding (ARB) technique. Recently, based on classical theories of precipitate and W.A.T. Clark a new multi-axis restraint deformation coarsening and isothermal softening data, technique (MAXStrain®) was developed was developed and found to provide a rea- The cleavage resistance of two microal- to study ultrafine-grained materials. This sonable description for weld thermal cycle loyed steels (steels A and B) was studied technique promised to easily produce much simulation (Gleeble) experiments. Recent using several tests, including the instru- larger-size metals, compared to other meth- work has shown, however, that softening mented precracked Charpy and Charpy V- ods developed. In this study, we adopted in real welds is not always well predicted notch (CVN) techniques. Ductile-to-brittle this multi-axis restraint deformation tech- by this model, so that additional effects, transition temperatures were measured for nique and developed the ultrafine grain which are not captured in conventional the base-metal and simulated heat-affected structures of a commercial aluminum alloy Gleeble thermal cycle simulations must be zone (HAZ) microstructures. Steel B AA5083 using the MAXStrain thermal- addressed. In Particular, the stresses asso- showed inferior cleavage resistance to steel mechanical simulator. The grain structures ciated with real weld HAZ’s may modify A, and this could not be explained by dif- of the deformed AA5083 were character- the softening kinetics. In the current work, ferences in gross microstructure. Scanning ized using electronic microscopes as a Gleeble simulations in both stress-free and electron fractography revealed that TiN function of strain. Mechanical properties stressed conditions have been conducted inclusions were responsible for cleavage were also evaluated and correlated with the and the kinetics compared. The accuracy initiation in steel B. These inclusions were resultant grain structures and the related of the thermal model predictions have also well bonded to the ferritic matrix. It is processing parameters. been considered regarding their impact on believed that a strong inclusion-matrix estimated hardness values. bond is a key factor in why TiN inclusions 485 are potent cleavage initiators in steel. 487 Strong bonding allows high stresses in a Effect of Boron on Hot Ductility of crack/notch-tip plastic zone to act on the Low Carbon Low Alloyed Steel Segregation of Phosphorus and inclusions without debonding the interface. by H.-W. Luo, P. Zhao, Y. Zhang, Sulfur in Heat-Affected Zone Hot Once an inclusion cleaves, the strong bond and Z.-J. Dang Cracking of Type 308 Stainless Steel allows for transfer of the TiN crack into the by L. Li and R.W. Messler, Jr. ferritic matrix. It was estimated that only The influence of boron on the hot ductil- 0.0016 wt pct Ti was tied up in the offend- ity of C-Mn-Al-Cr steel has been investi- The Auger microprobe analysis method ing inclusion in steel B. This indicates that gated. At < 980°C M(CB) precipitated out was employed to indentify the presence extended times at high temperatures during and about half of the boron content was and characterize the degree of interfacial the casting of such steels could produce in solution in austenite at < 900°C. It was segregation of P and S associated with TiN-related toughness deterioration at even found that solute boron atoms segregate to weld heat-affected zone hot cracking in modest Ti contents. austenite grain boundaries and occupy the Type 308 austenitic stainless steel. Crack vacancies induced by deformation. This surface samples for Auger analysis were 482 prevents the formation and propagation produced under a controlled evacuated of microcracks at boundaries and results and argon back-filled atmosphere on a Development of Ultrafine Grained in improved hot ductility and a reduced Gleeble® thermomechanical simulator. AA5083 Using MAXStrain® Thermal dynamic recrystallisation temperature. Sulfur was found to strongly segregate to Mechanical Simulator the intergranular fracture surface, while by W. Chen, D. Ferguson, H. Ferguson, 486 segregation of P, confirmed by earlier R. Mishra and Z. Jin EDS analysis, was undetected by the Stressed Heat Affected Zone Auger equipment employed. The rela- Ultrafine grain structures of metallic Simulations of AerMet® 100 Alloy tively stronger tendency for S to segregate materials have become more and more by Joseph D. Puskar correlates well with this elements’ higher attractive to academic and industry diffusion rate compared to P and with researchers due to their high strength and AerMet® 100 is a high strength, high frac- cracking susceptibility test results, which high toughness. Several techniques have ture toughness alloy designed for use in showed S to be more detrimental that P to been developed to produce the ultrafine aerospace applications. In previous work HAZ cracking. Using Type B Thermocouples Come See Us at The use of type B thermocouples is not use type B thermocouples for impor- the Shows becoming more popular among Gleeble tant temperature measurements below operators because they have greater sta- 800°C. Continued from Page 1 bility at high temperatures and are not We recommend power control for the Topics will include: affected by oxygen as are tungsten ther- initial heating of the specimen. As starting • Welding processes: conventional mocouples. Before you use a type B ther- place for power control when transitioning arc welding, resistance (spot) weld- mocouple, however, there are some things to thermocouple control using a type B ing, solid state welding such as fric- you should know: thermocouples with a 10 mm steel speci- tion stir welding, etc. • Because of a double-valued perfor- men, try the following: • Metallic materials: steels, alumin- mance curve and extremely low setback • Set power angle to 40° ium, titanium, magnesium, nickel, etc. coefficient at low temperatures, the type • Wait tcl > 400°C • Similar and dissimilar joining B thermocouple is virtually useless