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SOUTH AFRICAN QUALIFICATIONS AUTHORITY 
REGISTERED UNIT STANDARD: 

Demonstrate an understanding of chemical reactions in, and the solidification of, liquid metals 
SAQA US ID UNIT STANDARD TITLE
264038  Demonstrate an understanding of chemical reactions in, and the solidification of, liquid metals 
ORIGINATOR
SGB Manufacturing and Assembly Processes 
PRIMARY OR DELEGATED QUALITY ASSURANCE FUNCTIONARY
-  
FIELD SUBFIELD
Field 06 - Manufacturing, Engineering and Technology Fabrication and Extraction 
ABET BAND UNIT STANDARD TYPE PRE-2009 NQF LEVEL NQF LEVEL CREDITS
Undefined  Regular  Level 3  NQF Level 03 
REGISTRATION STATUS REGISTRATION START DATE REGISTRATION END DATE SAQA DECISION NUMBER
Reregistered  2018-07-01  2023-06-30  SAQA 06120/18 
LAST DATE FOR ENROLMENT LAST DATE FOR ACHIEVEMENT
2024-06-30   2027-06-30  

In all of the tables in this document, both the pre-2009 NQF Level and the NQF Level is shown. In the text (purpose statements, qualification rules, etc), any references to NQF Levels are to the pre-2009 levels unless specifically stated otherwise.  

This unit standard does not replace any other unit standard and is not replaced by any other unit standard. 

PURPOSE OF THE UNIT STANDARD 
This unit standard is for people who work, or intend to work in a manufacturing process or similar environment where they need to apply principles of metallurgy. It will contribute towards the achievement of a National Certificate in a manufacturing process or similar environment at NQF Level 3.

Persons credited with this unit standard are able to demonstrate understanding of:
  • Melting and manufacturing processes for the production of metal goods.
  • The behaviour of pure liquid metals and the effects of adding elements/compounds to them.
  • The interaction of oxygen with elements and compounds in the liquid metal and slag.
  • The solidification of a pure metal.
  • The solidification of binary alloys and associated effects.
  • The upper (solidification) part of the binary phase diagram of the main alloy in the learner's melting environment. 

  • LEARNING ASSUMED TO BE IN PLACE AND RECOGNITION OF PRIOR LEARNING 
    The credits allocated to this unit standard assume that the learner has a National Certificate in Foundry Operations NQF Level 2 or an equivalent qualification. It also assume that the learner is working towards a qualification as part of a learning programme, which integrates all the required unit standards.

    The learning time will increase if the learner does not have:
  • A relevant NQF 2 qualification.
  • Experience in a relevant field.
  • Demonstrated competence in unit standards:
    > Demonstrate knowledge of introductory principles of metallurgy at NQF Level 2.
    > NLRD 12768 Fundamental chemical and physical reactions at NQF Level 3.

    The learning time will be decreased if the learner has experience in this field because:
  • The learning programme will be adjusted to build on what the learner already knows.
  • The learner can apply to have prior learning recognised. 

  • UNIT STANDARD RANGE 
    N/A 

    Specific Outcomes and Assessment Criteria: 

    SPECIFIC OUTCOME 1 
    Demonstrate understanding of the various melting processes and manufacturing routes for metal products. 
    OUTCOME RANGE 
    Routes and processes include raw materials used, conversion, casting, fettling, rolling, forging, pressing, drawing, extruding, cutting, welding, heat treatment, and machining. 

    ASSESSMENT CRITERIA
     

    ASSESSMENT CRITERION 1 
    Methods of producing liquid metal from ore and/or scrap are discussed and compared according to metal melting practices. 
    ASSESSMENT CRITERION RANGE 
    Methods include Blast Furnace, Basic Oxygen Converter (BOF), Cupola, Arc and Induction Furnaces.
     

    ASSESSMENT CRITERION 2 
    Methods of casting liquid metal into semi products are discussed according to metal melting practices. 
    ASSESSMENT CRITERION RANGE 
    Methods include Continuous casting, ingot casting, sand and die casting.
     

    ASSESSMENT CRITERION 3 
    Manufacturing methods to produce finished metal products from semi products are described according to standard operating procedures. 

    SPECIFIC OUTCOME 2 
    Demonstrate understanding of the behaviour of pure liquid metals. 

    ASSESSMENT CRITERIA
     

    ASSESSMENT CRITERION 1 
    Understanding of the movement of atoms in a pure liquid metal, as opposed to a solid metal, is shown according to principles of metallurgy. 

    ASSESSMENT CRITERION 2 
    The effect of temperature on the viscosity of a liquid metal is discussed according to principles of metallurgy. 

    ASSESSMENT CRITERION 3 
    Understanding of the possible outcomes of adding a second element to a liquid metal is shown according to principles of metallurgy. 
    ASSESSMENT CRITERION RANGE 
    Outcomes include Full solubility, partial solubility (solubility limit), immiscibility, formation of a compound.
     

    ASSESSMENT CRITERION 4 
    The effects of adding a second element to a liquid metal on its temperature is discussed according to principles of metallurgy. 
    ASSESSMENT CRITERION RANGE 
    Effects include Dissolution, chemical reaction, exothermic, endothermic.
     

    SPECIFIC OUTCOME 3 
    Demonstrate understanding of the interaction of oxygen with various elements and compounds in a liquid metal bath. 

    ASSESSMENT CRITERIA
     

    ASSESSMENT CRITERION 1 
    The affinity for oxygen of various metallic and non-metallic elements in a liquid metal is discussed according to principles of metallurgy. 
    ASSESSMENT CRITERION RANGE 
    Elements include Au, Ag, Ni, Cu, C, Fe, Mn, Cr, Si, V, Al, Zr, Mg, and Ca.
     

    ASSESSMENT CRITERION 2 
    The chemical formula for various oxides that occur in molten metals and slags is given according to principles of metallurgy. 
    ASSESSMENT CRITERION RANGE 
    Oxides include those of Fe, C, Si, Mn, Cr, Al, Mg, Ca, Ti, and Zr.
     

    ASSESSMENT CRITERION 3 
    Factors influencing oxidation and reduction reactions in molten metals and slags are discussed according to principles of metallurgy. 
    ASSESSMENT CRITERION RANGE 
    Factors include oxide stability (affinity), concentrations and temperature.
     

    ASSESSMENT CRITERION 4 
    Types of slag and their properties when melting are discussed according to principles of metallurgy. 
    ASSESSMENT CRITERION RANGE 
    Properties include basicity, viscosity and oxygen potential.
     

    ASSESSMENT CRITERION 5 
    Interactions between slag and the liquid metal are explained according to principles of metallurgy. 

    ASSESSMENT CRITERION 6 
    Carbon boil and oxygen blowing are discussed according to metal refining practices. 
    ASSESSMENT CRITERION RANGE 
    Discussion includes effects on composition and temperature, removal of gases, slag foaming.
     

    ASSESSMENT CRITERION 7 
    Deoxidation of the liquid metal is discussed according to principles of metallurgy. 
    ASSESSMENT CRITERION RANGE 
    Discussion includes reasons for deoxidation and methods of deoxidation.
     

    SPECIFIC OUTCOME 4 
    Demonstrate understanding of the solidification of pure metals. 

    ASSESSMENT CRITERIA
     

    ASSESSMENT CRITERION 1 
    The transition, on an atomic scale, from the liquid phase to the solid phase is explained for a pure metal according to principles of metallurgy. 

    ASSESSMENT CRITERION 2 
    The physical effects of the transition from a liquid to a solid state are explained according to principles of metallurgy. 
    ASSESSMENT CRITERION RANGE 
    Physical effects include volume change and heat release.
     

    ASSESSMENT CRITERION 3 
    Factors affecting the initiation and progress of solidification are discussed according to principles of metallurgy. 
    ASSESSMENT CRITERION RANGE 
    Factors include super cooling, nucleation, heat transfer and temperature gradients.
     

    ASSESSMENT CRITERION 4 
    The formation of equi-axed grains (crystals) is discussed according to principles of metallurgy. 

    ASSESSMENT CRITERION 5 
    Inoculation is discussed according to principles of metallurgy. 

    SPECIFIC OUTCOME 5 
    Demonstrate understanding of the solidification of binary alloys. 

    ASSESSMENT CRITERIA
     

    ASSESSMENT CRITERION 1 
    The solidification of a binary alloy with full solid solubility is discussed according to principles of metallurgy. 
    ASSESSMENT CRITERION RANGE 
  • Example used for discussion may be Cu-Ni.
  • Topics of discussion include liquidus and solidus, segregation, columnar (dendritic) growth.
     

  • ASSESSMENT CRITERION 2 
    The solidification of a binary alloy with partial solid solubility is discussed according to principles of metallurgy. 
    ASSESSMENT CRITERION RANGE 
  • Example used for discussion may be Pb-Sn (solder).
  • Topics of discussion are segregation and the formation of a eutectic phase.
     

  • ASSESSMENT CRITERION 3 
    The solidification of a binary alloy which forms a compound at a certain concentration is discussed according to principles of metallurgy. 
    ASSESSMENT CRITERION RANGE 
  • Example used for discussion may be Iron with 0,5- 5% Carbon.
  • Topics of discussion are segregation and the formation of a compound and a eutectic phase.
     

  • ASSESSMENT CRITERION 4 
    The importance of casting at the correct temperature is discussed according to principles of metallurgy. 

    SPECIFIC OUTCOME 6 
    Demonstrate understanding of the upper part of the binary phase diagram applicable to the type of metal(s) produced. 
    OUTCOME RANGE 
  • For an iron or steel producer: the Fe-C diagram, above 1000oC and up to 6% C.
  • For a light alloys producer: the Al-Cu diagram up to 50% Cu, or the Al-Si diagram up to 20% Si, or the Al-Mg diagram up to 40% Mg; or the Mg-Al diagram up to 50% Al.
  • For a cuprous producer: the Cu-Sn diagram, above 600oC and up to 30% Sn. 

  • ASSESSMENT CRITERIA
     

    ASSESSMENT CRITERION 1 
    The applicable binary phase diagram is sketched and labelled according to principles of metallurgy. 

    ASSESSMENT CRITERION 2 
    The phases that will occur in the solidified metal are explained for various concentrations of the solute according to principles of metallurgy. 

    SPECIFIC OUTCOME 7 
    Prepare and interpret metallographic samples. 
    OUTCOME RANGE 
  • Sample preparation includes grinding, polishing and etching.
  • The metallographic samples include features such as types of grain, segregation patterns ("coring"), eutectics and compounds (carbides, oxides). 

  • ASSESSMENT CRITERIA
     

    ASSESSMENT CRITERION 1 
    Metal samples are received, ground, polished and etched to the required standard according to standard operating procedures. 

    ASSESSMENT CRITERION 2 
    Microstructures are observed and explained according to principles of metallurgy. 

    ASSESSMENT CRITERION 3 
    Associated documents are completed and processed according to standard operating procedures. 

    ASSESSMENT CRITERION 4 
    Samples are labelled and stored for easy retrieval according to standard operating procedures. 


    UNIT STANDARD ACCREDITATION AND MODERATION OPTIONS 
  • An assessor, accredited with a relevant NQF Level 4 or higher qualification, will assess the learner's competency. Only an Assessor with suitable first hand experience in process operations will assess the learner's competency.
  • Anyone assessing a learner or moderating the assessment of a learner against the qualification must be registered as an assessor with the relevant Education, Training, Quality, Assurance (ETQA) Body, or with an ETQA that has a Memorandum of Understanding with the relevant ETQA.
  • Any institution offering learning that will enable the achievement of this qualification must be accredited as a provider with the relevant Education, Training, Quality, Assurance (ETQA) Body, or with an ETQA that has a Memorandum of Understanding with the relevant ETQA.
  • Assessment and moderation of assessment will be overseen by the relevant Education, Training, Quality, Assurance (ETQA) Body, or by an ETQA that has a Memorandum of Understanding with the relevant ETQA, according to the ETQA's policies and guidelines for assessment and moderation.
  • Moderation must include both internal and external moderation of assessments, unless ETQA policies specify otherwise. Moderation should also encompass achievement of the competence described in the associated unit standards.
  • Anyone wishing to be assessed against this qualification may apply to be assessed by any assessment agency, assessor or provider institution that is accredited by the relevant ETQA. 

  • UNIT STANDARD ESSENTIAL EMBEDDED KNOWLEDGE 
    Things I know and can explain:

    Names & functions of:
  • Melting processes.
  • Casting processes.
  • Forming processes.

    Attributes, descriptions, characteristics & properties:
  • Reactivity (affinity for oxygen).
  • Viscosity.
  • Basicity.
  • Metallographic samples.
  • Micro-structures in metallographic samples.

    Sensory cues:
  • Colour of molten metal (temperature).
  • Colour of solid slags (basicity).

    Purpose of:
  • Slag and slag removal.
  • Oxygen blowing.
  • Deoxidation.
  • Inoculation.
  • Metallographic samples.

    Processes, events, causes and effects, implications:
  • Additions to modify slags.
  • The effects of blowing oxygen.
  • The effects of pouring the metal too cold/too hot.

    Procedures and techniques:
  • Controlling temperature.
  • Controlling slag.
  • Controlling metal composition.
  • Preparing and interpreting metallographic samples.

    Regulations, legislation, agreements, policies, standards:
  • Standard operating procedures.

    Theory, rules, principles, laws.
  • Oxidation and reduction.
  • Solidification energy.
  • Heat transfer.

    Relationships, systems:
  • The relationship between blowing oxygen and changes in the liquid metal composition.
  • The relationship between too cold / too hot metal pouring and defects in the cast product. 

  • UNIT STANDARD DEVELOPMENTAL OUTCOME 
    N/A 

    UNIT STANDARD LINKAGES 
    N/A 


    Critical Cross-field Outcomes (CCFO): 

    UNIT STANDARD CCFO IDENTIFYING 
    Identify and solve problems:
  • Relating to composition and temperature control of molten metal. 

  • UNIT STANDARD CCFO ORGANISING 
    Organise and manage my activities and myself:
  • By organising the necessary activities to prepare and interpret metallographic samples. 

  • UNIT STANDARD CCFO COLLECTING 
    Collect, analyse, organise and critically evaluate information:
  • By analysing data relating to the composition and temperature of the metal at different stages of melting and evaluating the final results. 

  • UNIT STANDARD CCFO COMMUNICATING 
    Communicate effectively:
  • By explaining concepts clearly whilst highlighting aspects of importance/explaining concepts clearly through my oral discussions and free hand sketches. 

  • UNIT STANDARD ASSESSOR CRITERIA 
    N/A 

    REREGISTRATION HISTORY 
    As per the SAQA Board decision/s at that time, this unit standard was Reregistered in 2012; 2015. 

    UNIT STANDARD NOTES 
    N/A 

    QUALIFICATIONS UTILISING THIS UNIT STANDARD: 
      ID QUALIFICATION TITLE PRE-2009 NQF LEVEL NQF LEVEL STATUS END DATE PRIMARY OR DELEGATED QA FUNCTIONARY
    Elective  66449   National Certificate: Foundry Operations  Level 3  NQF Level 03  Passed the End Date -
    Status was "Reregistered" 
    2013-11-07  MERSETA 


    PROVIDERS CURRENTLY ACCREDITED TO OFFER THIS UNIT STANDARD: 
    This information shows the current accreditations (i.e. those not past their accreditation end dates), and is the most complete record available to SAQA as of today. Some Primary or Delegated Quality Assurance Functionaries have a lag in their recording systems for provider accreditation, in turn leading to a lag in notifying SAQA of all the providers that they have accredited to offer qualifications and unit standards, as well as any extensions to accreditation end dates. The relevant Primary or Delegated Quality Assurance Functionary should be notified if a record appears to be missing from here.
     
    1. QTE Training & Consulting cc T/A QTE (GERMISTON) (TP) 
    2. Scaw Metals Group (Pty) Ltd T/A Scaw Metals (DINWIDDIE) (TP) 



    All qualifications and part qualifications registered on the National Qualifications Framework are public property. Thus the only payment that can be made for them is for service and reproduction. It is illegal to sell this material for profit. If the material is reproduced or quoted, the South African Qualifications Authority (SAQA) should be acknowledged as the source.