Transcript causes

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
• SINCE
+ SENTENCE (S+Vb) porque, puesto que, ya que
• AS
Debido a + NOUN / Vb -ING
• DUE TO
• BECAUSE OF
• OWING TO
+ NOUN / VB -ING
Debido a QUE + SENTENCE (S+Vb)
• DUE TO THE FACT THAT
• BECAUSE OF THE FACT THAT
• OWING TO THE FACT THAT
+ (Sentence)
+ (Sentence)
+ (Sentence)
• ONE EFFECT / RESULT / CONSEQUENCE OF C IS E
CAUSE & EFFECT
VERBS
•
•
•
•
C RESULTS IN
C BRINGS ABOUT
C GIVES RISE TO
C LEADS TO
E dar como resultado
E provocar,
E implicar, suponer
E lleva/conduce a
• C CAUSES/ALLOWS E hace que (+Vb)
• C MAKES X + ADJ
Effect: X BECOMES (+adj) resulta + ADJ
CAUSE & EFFECT
EFFECT
•
•
•
•
•
•
•
•
•
THEREFORE,
THUS,
HENCE,
CONSEQUENTLY,
AS A CONSEQUENCE,
AS A RESULT,
DUE TO THIS,
THEREBY,
IN THIS WAY ,
…
por lo tanto
así,
así pues
como consecuencia,
de este modo
C SO THAT E de modo que / para que
EXERCISE
1. We use copper in wires due to its ductility
2. We mix pure metals with other materials so that we obtain the
required properties
3. Aluminium is used in structures as it is corrosion resistant
4. Aluminium is used in structures because of its corrosion
resistance
5. Tempering results in a decrease in hardness and ...
6. Plastics are insulators, thus they are used to cover wires
7. Annealed steel is more machineable since this process
releases internal stresses
8. With hardening, the metal becomes stronger
9. Iron is brittle. As a consequence it is mixed with other ...
10.Alloying is a way of changing the properties of metals. In this
way we can obtain materials with specific characteristics
QUESTIONS
1. Which two methods are used to change the properties of steel?
2. How does the carbon content affect the properties of steel?
3. What does heat treatment consist of?
4. What happens when we heat steel at a certain temperature?
5. Which are the three heat treatments?
6. What two steps are involved in the process of annealing?
7. Which are the results?
8. What happens when we cool the metal quickly?
9. What two steps are involved in the process of hardening?
10. What problem results from hardening and how can we solve
this?
11. Explain the process of tempering.
12. What is the difference between tempered steel and high carbon
steel?
TRUE/FALSE
1. Carbon makes steel harder. T (up to 1.5%)
2. When we want to make steel softer and easier
to machine we use annealing. T
3. Annealing increases the internal stresses in
the metal. F (Annealing releases stresses)
4. Steel can be hardened by cooling it slowly. F
(by cooling it fast)
5. High carbon steel can be easily worked
because it is soft. F (it becomes hard)
WORD FORMATION
•
•
•
•
•
PercentAGE
hammerING
contractION
crackING
temperING
•
•
•
•
•
annealiNG
cooliNG
DistortION
treatMENT
hardENING
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
EXERCISE CAUSE/ALLOW/PREVENT
1. B permit
2. C cause
3. B prevent
4. A causes
5. A permit
6. C cause
7. C prevent
8. B permit
9. B Permits …… prevents
10. A Prevent
LISTENING: STEEL
1. an alloy of IRON and up to 1.7% CARBON, with small
amounts of manganese, phosphorous, sulfur, and
silicon
2. those with other metals
3. low-alloy steels have LESS THAN 5% of the alloying
metal and high-alloy steels MORE THAN 5%.
4. Carbon steels are FAR STRONGER THAN IRON, and
their properties can be tailored to their uses by
adjusting COMPOSITION AND TREATMENT.
5. STAINLESS STEELS
6. Steel was first mass-produced in the MID-19TH
CENTURY
7. The USA, the former Soviet Union, and Japan are the
MAJOR PRODUCERS.
8. All steelmaking processes REMOVE THE IMPURITIES in
the raw materials …and reduce iron ore BY OXIDIZING
them WITH an air or oxygen blast
LISTENING: STEEL
9. THUS MOST OF THE CARBON, SILICON, manganese,
phosphorus and sulfur ARE CONVERTED TO THEIR
OXIDES and, …
10. The main processes are …or basic OXYGEN process,
11. …, used for HIGHEST-QUALITY STEEL; and the openhearth process.
12. When THE IMPURITIES HAVE BEEN REMOVED, desired
elements are added in calculated proportions
13. 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).
14. The PROPERTIES OF CARBON STEELS may be greatly
improved by HEAT TREATMENT: ANNEALING, CASE
HARDENING and TEMPERING
HEAT TREATMENT
• 1 THE PROPERTIES OF METALS CAN BE
CHANGED IN DIFFERENT WAYS. A COMMON
METHOD OF IMPROVING THEIR
CHARACTERISTICS IS BY ALLOYING
SEVERAL METALS. THIS METHOD
CONSISTS OF HEATING THE METALS UNTIL
THEY MELT IN ORDER TO OBTAIN THE
REQUIRED PROPERTIES. FOR EXAMPLE,
STEEL CONTAINING LITTLE CARBON WILL
be SOFTER than steel with more carbon
HEAT TREATMENT
• 2 ON THE OTHER HAND, THE
PROPERTIES OF STEEL CAN ALSO BE
IMPROVED BY HEAT TREATMENT.
THIS IS THE NAME GIVEN TO A
NUMBER OF PROCEDURES WHICH
CONSIST OF HEATING THE METAL UP
TO A CERTAIN TEMPERATURE AND
THEN ALLOW THE METAL TO COOL AT
DIFFERENT RATES
HEAT TREATMENT
• 3 ONE OF SUCH PROCEDURES IS KNOWN
AS ANNEALING. 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
HEAT TREATMENT
• 5 AS OPPOSED TO ANNEALING, WE CAN MAKE THE
METAL HARDER WITH THE PROCESS OF
HARDENING. IN THIS CASE, WE LET THE METAL
HEAT ABOVE ITS CRITICAL TEMPERATURE AND
THEN WE ALLOW IT TO COOL FAST.
• 6 ON THE CONTRARY TO WHAT HAPPENED IN THE
PROCESS OF ANNEALING, THE METAL OBTAINED
WILL BE HARDER; HOWEVER, IT WILL BE BRITTLE
SINCE THE RAPID COOLING CAUSES UNEQUAL
CONTRACTIONS TO OCCUR IN THE METAL, WHICH
GIVES RISE TO CRACKING
HEAT TREATMENT
• 7 IN ORDER TO AVOID THIS PROBLEM,
THE METAL CAN BE HEATED BELOW
ITS CRITICAL TEMPERATURE AND
INSTEAD OF COOLING IT QUICKLY WE
LET IT COOL SLOW LY; IN THIS WAY,
DESPITE THE METAL BEING HARD, IT
WILL ALSO BE TOUGH THUS
ALLOWING US TO SHAPE IT
WITHOUT FRACTURING