List of activities
- Materials Affordability Initiatives (MAI) such as:
- Development of a Cr-Mn low nickel austenitic stainless steel (Hercules)
- Development of novel and cost effective grinding media for the platinum industry
- Development of ultra-fine grained (UFG) steel and aluminium alloys for the automotive industry.
- Development of Al-Ti-C grain refiners for aluminium alloys
- Development of smart materials for structural health monitoring applications in the mining, petrochemical and aerospace industries.
Development of Cr-Mn Low Nickel Austenitic stainless Steel (The Hercules™ Alloy)
Hercules™ is a low nickel austenitic stainless steel (LNASS) that has been developed at Mintek by the base metals group, in the Advanced Materials Division, to address the fact that austenitic stainless steels, although possessing useful engineering properties, are not readily selected for structural applications due to their high cost per unit strength Hercules™ thus provides a cheaper alternative to conventional austenitic stainless steels, such as type 304 and 201, in structural applications.
The nickel content of Hercules™ has been reduced to 2 wt% and this has allowed a cost saving of 25% over that of type 304 stainless steel. Nitrogen and manganese have been added to counteract the effects of a reduced nickel content. Hercules™ has superior mechanical properties than type 304 and type 201 steels in the hot rolled condition, fatigue strength of about 500MPa and good formability. Hercules™ can be manufactured and welded using the same techniques as those for type 304. A more corrosion resistant alloy, Hercules™ B, with an addition of 0.5wt% molybdenum has also been developed.
Hercules™ can be applied in situations where high strength, toughness and a good degree of corrosion resistance is required. The alloy is targeted for the rebar and fasteners market and is currently in the commercialisation phase. It is currently available in bar form. Fastener prototypes have been manufactured (M16 and M24 hexagon head bolts) via hot forging and thread rolling. Work into a Hercules flat product is being considered.
Development of smart materials for structural health monitoring applications in the mining, petrochemical and aerospace industries (Smartbolt™)
Smartbolt™ was developed in 1999 by Mintek’s Base Metals Group (in the Advanced Materials Division) in partnership with the Safety in Mines Research Advisory Committee (SIMRAC) to address the need for an underground monitoring system that would detect stresses in the mine rock and give warning of potential rockfall or rockburst situations.
Smartbolt™ is a metastable austenitic stainless steel alloy that undergoes a microstructural transformation, from a non magnetic phase (austenite) to a magnetic phase (martensite) when stressed. The degree of transformation depends on the degree of plastic deformation. These microstructural changes lead to changes in longitudinal sound velocity through the Smartbolt™ which are measured by a portable ultrasonic device. Smartbolt™ can be used to measure uniaxial as well as multiaxial loading situations.
The fundamental abilities of awareness and reaction of the Smartbolt™ can be integrated into the mining rockbolt system with the minimum of complexity and cost. When compared to similar products on the market Smartbolt™ is unique in that it does not require active circuitry, it has good environmental stability, it takes up minimal space and its alloy composition can provide a wide range of measurable strains. It is more economical than the currently used carbon steel rock bolts because of its higher corrosion resistance, its durability and permanency. It can be used both as a support for mining roofs and as a sensor. As a trademarked product and winner of the 2005 SABS PROTOTYPE AWARD, Smartbolt™ will help promote safety in the mining industry. The Smartbolt™ alloy can also be used for structural health monitoring applications in the petrochemical and aerospace industries.
Development of Novel and Cost-Effective Grinding Media for the Platinum Industry.
Mintek not only performs quality checks on grinding media for clients but has also in the past carried out some work to develop grinding balls. This has resulted in the identification of a number of potential ball types, such as martensitic ductile iron balls or Austempered Ductile Iron (ADI) balls that could be developed into cost effective alternatives to the heat treated high chromium white cast iron (HCWCI) grinding balls used in the platinum industry. Mintek has been awarded a R5 million over 3 years funding from the DST-Innovation Fund to develop novel cost-effective grinding media for the platinum industry and also produce an industry standard specification for heat treated high chromium white cast iron (HCWCI) grinding balls.
Development of Ultra-Fine Grain (UFG) Steel and Aluminium Alloys for Automotive Applications.
The automotive industry faces a crucial weight problem resulting from increased customer demands in terms of safety and performance. This has forced car manufacturers to take action in the form of lightweight concepts, such as the ULSAB-AVC (Ultra Light Steel Autobody-Advanced Vehicle Concepts). The Mintek team has embarked on a project to develop alloys and novel processing methods that can be applied to automobiles and result in weight reduction. Mintek is presently considering aluminium and steel materials with the aim of producing alloys that have an ultra-fine grain (UFG) structure. UFG structures have the ability to impart high strengths to the material such that thinner sections can be used and weight saving can be achieved.
An UFG structure is produced through the use of severe plastic deformation (SPD) methods, such as equal channel angular pressing (ECAP), accumulative roll bonding (ARB) and multiple forging (MF). Mintek is interested in using the ARB process on its alloys and optimise the method to allow for upgrading to bulk production quantities. ARB is a form of solid-phase welding where two clean metal surfaces of equal dimension are stacked close together, heated and rolled, such that a metallic bond forms between them.
Work on two commercial alloys, SM490 and AA5083, has already began at Mintek. The success of this project would allow car manufactures to purchase locally produced auto body material thus allowing the beneficiation of the locally produced minerals used in the production of such materials. Increased demand in local UFG alloys by the car manufacturers will result in job creation and poverty alleviation.
Development of Al-Ti-C grain refiners for aluminium alloys (Aluhard-TiCAl)
This was a three year project sponsored by the Innovation Fund (NRF) for the development of additives (grain refiners) for aluminium and titanium alloys. In this project the process of the aluminothermic reduction of oxides through the use of a plasma arc furnace to produce aluminium master alloys was used.
In this project Al-Ti-B and Al-Ti-C grain refiners were developed and tested against similar commercially available grain refiners. All the manufactured grain refiners gave a grain size larger than the benchmarked commercial refiners. Research was then conducted to refine the processing methodology of the refiners with the intention of producing more efficient Al-Ti-C grain refiners using Al-Ti aluminothermic concentrate for Ti units and graphite powder for C units.
As-cast experimental TiCAl grain refiners were produced which performed better than commercially available “rod” grain refiners. These refiners were produced by reacting graphite powder with an aluminothermic reduction of TiO2 concentrate. The smallest grain size achieved was 165µm.
Other areas of interest:
- High temperature alloys
- autocats substrates
- Light metals
- Novel applications for magnesium alloys
- Novel joining techniques for aerospace materials
- Development of lead free solders
- Identify areas that are in need in South Africa.
9. Metals Technology Centre (Testing / Consultancy)
The Advanced Materials Division at Mintek undertakes development work on alloys, provides critical assistance with the selection and testing of materials, and solves difficult problems associated with their use in the most demanding applications. The Division is fully equipped to carry out a wide range of conventional and unconventional tests on the mechanical and corrosion properties to gauge and improve product performance.
Extensive work has been done to reduce the high cost of wear and corrosion in the mining and industrial environments, by means of on-site monitoring and testing as well as by the latest laboratory techniques. A variety of clients use the Division’s consulting services to improve their processes and product performance. The Division’s comprehensive resources can be brought to bear on any investigation, large or small, unique or typical. This cost-effective route is particularly valuable for smaller enterprises that lack the facilities to undertake such work themselves.
Mintek can help you solve your materials-related problems by:
- Cost-effective research Material selection and evaluation
- Material testing to standards
- Simulated material testing
- Material monitoring in plants
- Accelerated material testing
- Failure analysis
- Corrosion surveys
The facilities available include:
- Electrochemical corrosion laboratory and portable equipment for on-site corrosion monitoring
- Laboratory coupon testing over a wide range of temperature and pressure
- Full pilot plant and foundry for melting, casting, forging, and rolling, as well as specialised heat-treatment facilities
- Vacuum melting facility with vacuum induction, graphite resistance, and tungsten arc furnaces, and vacuum sintering
- Advanced laboratories for metallographic investigations, including scanning electron microscopy (SEM), X-ray diffraction (crystallographic texture) and image analysis
- Sophisticated computerised equipment for measuring mechanical properties such as fatigue-crack propagation, fracture toughness, and tensile properties
- Wear testing including Pin-on-Belt (for high stress abrasion) and an experimental ball mill (for testing grinding media)