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UNIT 5 CAUSE & EFFECT

UNIT 5 CAUSE & EFFECT. Vocabulary Heat treatment of steel: annealing hardening Tempering WORD FORMATION ( U2 -> p28 ): N from Vbs Grammar and functions Expressing cause & effect ALLOW / CAUSE / AVOID. CAUSE & EFFECT. CAUSE BECAUSE

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UNIT 5 CAUSE & EFFECT

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  1. UNIT 5CAUSE & EFFECT Vocabulary • Heat treatment of steel: • annealing • hardening • Tempering • WORD FORMATION (U2 -> p28): N from Vbs Grammar and functions • Expressing cause & effect • ALLOW / CAUSE / AVOID

  2. CAUSE & EFFECT CAUSE • BECAUSE • SINCE + SENTENCE (S+Vb)porque, puesto que, ya que • AS Debido a + NOUN / Vb -ING • DUE TO • BECAUSE OF + NOUN / VB -ING • OWING TO Debido a QUE + SENTENCE (S+Vb) • DUE TO THE FACT THAT + (Sentence) • BECAUSE OF THE FACT THAT + (Sentence) • OWING TO THE FACT THAT + (Sentence) • ONE EFFECT / RESULT / CONSEQUENCE OFCISE

  3. CAUSE & EFFECT VERBS • CRESULTS INE darcomoresultado • C BRINGS ABOUTE provocar, • C GIVES RISE TOE implicar, suponer • C LEADS TO E lleva/conduce a • C CAUSES/ALLOWS Ehace que (+Vb) • C MAKES X + ADJ Effect: X BECOMES (+adj) resulta + ADJ

  4. CAUSE & EFFECT EFFECT • THEREFORE,por lo tanto • THUS, así, • HENCE, así pues • CONSEQUENTLY, • AS A CONSEQUENCE, • AS A RESULT, • DUE TO THIS, como consecuencia, • THEREBY, de este modo • INTHIS WAY , … CSO THATE de modo que / para que

  5. EXERCISE • We use copper in wires due to its ductility • We mix pure metals with other materials so that we obtain the required properties • Aluminium is used in structures as it is corrosion resistant • Aluminium is used in structures because of its corrosion resistance • Tempering results in a decrease in hardness and ... • Plastics are insulators, thus they are used to cover wires • Annealed steel is more machineable since this process releases internal stresses • With hardening, the metal becomes stronger • Iron is brittle. As a consequence it is mixed with other ... • Alloying is a way of changing the properties of metals. In this way we can obtain materials with specific characteristics

  6. QUESTIONS • Which two methods are used to change the properties of steel? • How does the carbon content affect the properties of steel? • What does heat treatment consist of? • What happens when we heat steel at a certain temperature? • Which are the three heat treatments? • What two steps are involved in the process of annealing? • Which are the results? • What happens when we cool the metal quickly? • What two steps are involved in the process of hardening? • What problem results from hardening and how can we solve this? • Explain the process of tempering. • What is the difference between tempered steel and high carbon steel?

  7. TRUE/FALSE • Carbon makes steel harder. T (up to 1.5%) • When we want to make steel softer and easier to machine we use annealing. T • Annealing increases the internal stresses in the metal. F (Annealing releases stresses) • Steel can be hardened by cooling it slowly. F (by cooling it fast) • High carbon steel can be easily worked because it is soft. F (it becomes hard)

  8. PercentAGE hammerING contractION crackING temperING annealiNG cooliNG DistortION treatMENT hardENING WORD FORMATION

  9. CAUSE/PERMIT/PREVENT CAUSE: TO CAUSE + OBJ + TO INFINITIVE TO MAKE + OBJ + BASE FORM OF THE VERB hacer que + frase PERMIT: TO PERMIT + OBJECT + TO INFINITIVE TO ALLOW + OBJECT + TO INFINITIVE TO ENABLE + OBJECT + TO INFINITIVE TO LET + OBJECT + BASE FORM OF THE VERB permitir que + frase PREVENT: TO PREVENT + OBJECT + FROM + -ING TO AVOID + OBJECT + FROM + -ING TO STOP + OBJECT + FROM + -ING TO KEEP + OBJECT + FROM + -ING impedir que + frase

  10. EXERCISE CAUSE/ALLOW/PREVENT • B permit • C cause • B prevent • A causes • A permit • C cause • C prevent • B permit • B Permits …… prevents • A Prevent

  11. LISTENING: STEEL • an alloy of IRON and up to 1.7% CARBON, with small amounts of manganese, phosphorous, sulfur, and silicon • those with other metals • low-alloy steels have LESS THAN 5% of the alloying metal and high-alloy steels MORE THAN 5%. • Carbon steels are FAR STRONGER THAN IRON, and their properties can be tailored to their uses by adjusting COMPOSITION AND TREATMENT. • STAINLESS STEELS • Steel was first mass-produced in the MID-19TH CENTURY • The USA, the former Soviet Union, and Japan are the MAJOR PRODUCERS. • All steelmaking processes REMOVE THE IMPURITIES in the raw materials …and reduce iron ore BY OXIDIZING them WITH an air or oxygen blast

  12. LISTENING: STEEL • THUS MOST OF THE CARBON, SILICON, manganese, phosphorus and sulfur ARE CONVERTED TO THEIR OXIDES and, … • The main processes are …or basic OXYGEN process, • …, used for HIGHEST-QUALITY STEEL; and the open-hearth process. • When THE IMPURITIES HAVE BEEN REMOVED, desired elements are added in calculated proportions • steel is cast as INGOTS that are shaped while still red-hot in rolling mills, or it may be cast as a continuous bar (strand casting). • The PROPERTIES OF CARBON STEELS may be greatly improved by HEAT TREATMENT: ANNEALING, CASE HARDENING and TEMPERING

  13. HEAT TREATMENT • 1 THE PROPERTIES OF METALS CAN BECHANGEDINDIFFERENT WAYS. A COMMON METHOD OF IMPROVINGTHEIR CHARACTERISTICS IS BY ALLOYING SEVERAL METALS. THIS METHOD CONSISTSOF HEATINGTHEMETALS UNTIL THEY MELT IN ORDER TO OBTAIN THEREQUIRED PROPERTIES. FOR EXAMPLE, STEEL CONTAININGLITTLE CARBON WILL be SOFTER thansteel with more carbon

  14. HEAT TREATMENT • 2 ON THE OTHER HAND, THE PROPERTIES OF STEEL CAN ALSO BE IMPROVEDBY HEAT TREATMENT. THIS IS THE NAME GIVENTO A NUMBER OF PROCEDURES WHICH CONSIST OF HEATING THE METAL UP TOA CERTAIN TEMPERATURE AND THEN ALLOW THE METAL TO COOL ATDIFFERENT RATES

  15. HEAT TREATMENT • 3 ONE OF SUCH PROCEDURES IS KNOWN ASANNEALING. IN THIS PROCESS, STEEL IS HEATED ABOVE ITS CRITICAL TEMPERATURE AND THEN IT IS COOLED SLOWLY. • 4 AS A RESULT, THE METAL BECOMES SOFTER AND MORE EASILY MACHINEABLE DUE TO THE FACT THAT THIS PROCESS PREVENTS INTERNAL STRESSES FROM OCCURRING

  16. HEAT TREATMENT • 5 ASOPPOSED TO ANNEALING, WE CAN MAKE THE METAL HARDERWITH THE PROCESS OF HARDENING. IN THIS CASE, WE LET THEMETAL HEAT ABOVE ITSCRITICAL TEMPERATURE AND THEN WE ALLOW IT TO COOL FAST. • 6 ON THE CONTRARY TO WHAT HAPPENED IN THE PROCESS OF ANNEALING, THE METAL OBTAINEDWILL BE HARDER; HOWEVER, IT WILL BE BRITTLESINCETHE RAPID COOLING CAUSES UNEQUAL CONTRACTIONS TO OCCUR IN THE METAL, WHICH GIVES RISE TO CRACKING

  17. HEAT TREATMENT • 7 IN ORDER TO AVOID THIS PROBLEM, THE METAL CAN BE HEATEDBELOW ITSCRITICAL TEMPERATURE AND INSTEAD OF COOLINGIT QUICKLYWE LET IT COOL SLOW LY; INTHIS WAY, DESPITE THE METAL BEING HARD, IT WILL ALSO BE TOUGH THUS ALLOWING US TO SHAPE IT WITHOUT FRACTURING

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