The Evidence Guide provides advice on assessment and must be read in conjunction with the Performance Criteria, Required Skills and Knowledge, the Range Statement and the Assessment Guidelines for the Training Package.

Overview of assessment

A person who demonstrates competency in this unit must be able to determine and supervise heat treatment of metal. Critical aspects for assessment and evidence are required to demonstrate competency in this unit.

Critical aspects for assessment and evidence required to demonstrate competency in this unit

It is essential that competence is demonstrated in the ability to:

Select the appropriate heat treatment cycle(s) for nominated materials, so that they meet the required physical properties.

Relationship to other units

This unit could be assessed in conjunction with any other units addressing the safety, quality, communication, materials handling, recording and reporting associated with applying basic scientific principles and techniques in mechanical engineering situations or other units requiring the exercise of the skills and knowledge covered by this unit.

Assessment method and context

This unit may be assessed on the job, off the job or a combination of both on and off the job. Where assessment occurs off the job, that is the candidate is not in productive work, then an appropriate simulation must be used where the range of conditions reflects realistic workplace situations. The competencies covered by this unit would be demonstrated by an individual working alone or as part of a team. The assessment environment should not disadvantage the candidate.

Assessors should gather a range of evidence that is valid, sufficient, current and authentic. Evidence can be gathered through a variety of ways including direct observation, supervisor's reports, project work, samples and questioning. Questioning techniques should not require language, literacy and numeracy skills beyond those required in this unit of competency. The candidate must have access to all tools, equipment, materials and documentation required. The candidate must be permitted to refer to any relevant workplace procedures, product and manufacturing specifications, codes, standards, manuals and reference materials.

Assessors must be satisfied that the candidate can competently and consistently perform all elements of the unit as specified by the criteria, including required knowledge, and be capable of applying the competency in new and different situations and contexts.

Resource implications

This section should be read in conjunction with the range of variables for this unit of competency. Resources required include suitable access to a situation where heat treatment of metal is undertaken. A bank of case studies/scenarios and questions will also be required to the extent that they form part of the assessment method. Questioning may take place either in the workplace, or in an adjacent, quiet facility such as an office or lunchroom. No other special resources are required.

This describes the essential skills and knowledge and their level, required for this unit.

Required skills:

select appropriate scientific principles to suit specific heat treatment applications

select appropriate techniques and associated software and hardware technologies, to suit specific applications in heat treatment

apply and manipulate appropriate formulas for heat treatment applications involving engineering calculations

apply appropriate calculations to engineering situations

refer solutions to the original aim of the application.

quote solutions for the application in appropriate units, using appropriate significant figures.

quote limitations of solutions for the application, due to assumptions, scientific principles and techniques used

present solutions for the application referring to the original aim of the application including elimination or containment of risks and establishing of safety procedures

Required knowledge:

Competency includes sufficient knowledge of:

heat treatment principles as given in the range statement

limitations of selected scientific principles

risks and safety procedures appropriate to heat treatment of metals and alloys

The range statement relates to the unit of competency as a whole. It allows for different work environments and situations that may affect performance. Bold italicised wording, if used in the performance criteria, is detailed below. Essential operating conditions that may be present with training and assessment (depending on the work situation, needs of the candidate, accessibility of the item, and local industry and regional contexts) may also be included.

Codes of practice/standards

Where reference is made to industry codes of practice, and/or Australian/international standards, it is expected the latest version will be used.

Sources of information

reference texts

manufacturers' catalogues and industrial magazines

websites

use of phone, email and fax information gathering

Scientific techniques and principles of heat treatment relate to:

Ferrous heat treatment

the iron-carbon equilibrium and plain carbon steels.

iron-carbon phase equilibrium

austenite-ferrite transformation

austenite-pearlite steels

influence of grain size and carbide distribution on mechanical properties.

microstructure and properties of slowly cooled steels.

effect of temperature and composition on structure and properties.

effects of alloying elements in iron-carbon alloys.

the gamma and sigma phase fields

distribution of alloying elements in steel.

effects of alloying elements in the kinetics of gamma and sigma transformations.

structural changes resulting for alloying additions.

transformation diagrams for alloy steels.

isothermal transformation of austenite.

austenite grain size

formation of pearlite

formation of bainite

role of alloying elements

mechanical properties of pearlite and bainite

Temperature Time Transformation (TTT) diagrams.

quenching treatments.

formation of martensite

morphology and crystallography of ferrous martensites

mechanical properties of martensites

retained austenite

quenching media - stages of quenching, effect of variables

thermal and transformation stresses, quenching defects.

transformation of austenite continuous cooling

cooling curves

Continuous Cooling Transformation (CCT) diagrams

hardening and heat treatment.

factors affecting how well a metal responds to hardening processes

use of TTT and CCT diagrams

hardenability testing e.g. Jominy

hardenability and heat treatment

tempering

tempering of irons and steels.

tempering of non ferrous metals and alloys

mechanical properties of tempered irons and steels

mechanical properties of non ferrous metals and alloys

Special heat treatments

austempering

martempering (marquenching)

maraging steels

high-strength, low-alloy (HSLA) steels.

surface treatments

carburising

carbonitriding

nitriding

induction and flame hardening

other methods

heat treatment defects

nature and prevention of defects

surface

structural and property

stress related

dimensional

embrittlement

Non-ferrous heat treatments

aluminium alloys

solutions treatments

quenching

precipitation hardening

coldworking

temper designations

copper alloys

solution annealing

age hardening

precipitation hardening

coldworking

quenching and tempering

miscellaneous non-ferrous

Significant figures

Are those relevant to accuracy and are appropriate to the process, data and desired range of results

Risks and safety procedures

biological factors in quench tank fluids

carcinogenic oil fumes,

flash point of oils and risk of fire in oil quenching

inert atmospheres and their potential to cause asphyxiation

specification and use of personal protective equipment (PPE)

location of emergency switches

tagging and isolation procedures

atmosphere control

identification of high risk alloys and metals

appropriate transfer times to quench and from quench to temper furnace