Presentation on the topic of cast iron. Classification of cast iron Yu.A. Dementiev Regional State Educational Institution of Primary Vocational Education "Vocational School

Developer: Kremis E.P.

Purpose: to study cast iron Tasks:

- to study:
influence of permanent impurities on the structure and properties
cast iron;
classification of cast irons;
properties and applications of cast irons
marking of cast iron according to GOST;
-learn to:
choose the type of cast iron for the manufacture of machine parts;
decipher grades of cast iron.

Alloys of iron with carbon containing carbon from 2.14 to 6.67% are called cast irons.

Approximate influence of elements on the structure of cast iron
Influence
Elements
Content in %
Relative graphitizing
action
to the main
metal
mass
Decrease
content
perlite
for graphite
at
hardening
in solid
able
Increase
quantity and
enlargement
+ 1,0
+ 1,0
Silicon
Up to 3.0
Carbon
Manganese
Over 1.7
» 0.8
Same
Crushing
perlite
Same
Weak
crushing
+ 1,0
+0.2 to +0.5
» 1.0
Education
sulfurous
manganese
Same, but less
- 0,2
» -0.2 » 0.5
Phosphorus
Up to 1.0
Education
phosphides
Influences weakly
+ 0,1
» + 0.1 » -0.2
Sulfur
» 0.2
Education
sulfides
Decrease
quantity
- 2,0
"-2"-4
Nickel
» 1.5
Crushing
perlite
+ 0,4
» + 0.4 » - 0.2
Chromium
» 1.0
Same
- 1,2
» - 1.2 » - 3.0
Increase
quantity and
weak
crushing
Decrease
quantity and
weak
crushing
Notes: 1. The sign "+" means positive, and the sign "-" means negative influence.

graphitization process.

graphitization process
.
Graphite is a polymorphic modification of carbon.
Methods for the formation of graphite in cast iron
- from liquid phase;
- during the decomposition of previously formed cementite.
Graphitization from the liquid phase, as well as from decay
primary cementite and cementite, which is part of
eutectics are called the primary stage of graphitization.
The separation of secondary graphite from austenite is called
intermediate stage of graphitization.
The formation of eutectoid graphite, as well as graphite,
formed as a result of cementite, which is part of
pearlite is called the secondary stage of graphitization.

Graphite forms: lamellar; globular; flaky; vermicular.

Cast iron classification

Depending on the state of carbon in cast iron, there are:
white cast iron - carbon in a bound state in the form of cementite, in
the fracture is white and has a metallic sheen
gray cast iron all or most of the carbon is in
free state as graphite
half - part of the carbon is in the free
state in the form of graphite
high strength
spherical shape
malleable iron
form
cast iron
graphite
inclusion
have
- graphite inclusions have a flaky

Depending on the shape of the graphite and
the conditions of its formation are distinguished
the following groups of cast irons
gray - with lamellar graphite
high-strength - with spherical
graphite
malleable - with flaky graphite

Schemes of cast iron microstructures depending on the metal base and the shape of graphite inclusions

Gray cast iron
Properties
The mechanical properties of gray cast iron depend on
number and size of graphite inclusions. By
compared to a metal base, graphite has
low strength. Therefore, graphite inclusions
can be considered discontinuities,
weakening the metal base. Because
lamellar inclusions most strongly weaken
metal base, gray cast iron has the most
low characteristics, both strength and
plasticity among all engineering
cast irons. Reducing the size of graphite inclusions
improves mechanical properties.

Application

Considering the low resistance of castings from gray
cast iron tensile and impact loads should be
use this material for parts that
subjected to compression or bending
loads. In machine tool building, these are basic, case
parts, brackets, gears, guides;
in the automotive industry - cylinder blocks, piston rings,
camshafts, clutch discs. Castings from
gray cast iron are also used in
electrical engineering, for the manufacture of goods
popular consumption.

Ductile iron
Properties
These cast irons have high fluidity,
linear shrinkage - about 1%. Foundry stresses in
castings are slightly higher than for gray cast iron. Due to the high modulus of elasticity, quite high
machinability. Possess
satisfactory weldability.

Application

Ductile iron is used to make thin-walled
castings (piston rings), forging
hammers, beds and frames of presses and rolling mills,
molds, tool holders, faceplates.
Castings of crankshafts weighing up to 2..3 tons, instead of
forged steel shafts, have a higher
cyclic viscosity, insensitive to
external voltage concentrators, have
the best anti-friction properties and
much cheaper.

malleable iron
Properties
Ferritic malleable cast irons (KCh 33-8, KCh 37-12) have
higher ductility, and pearlitic
(KCh 50-4, KCh 60-3) higher strength

Application

Ductile iron castings are used for parts
operating under shock and vibration loads.
Crankcases are made from ferritic cast irons
gearboxes, hubs, hooks, brackets, clamps, couplings,
flanges.
Forks are made from pearlitic cast iron
cardan shafts, links and rollers of conveyor chains,
brake pads.

Chilled and other cast irons Chilled cast irons are castings that have a white cast iron surface and gray or ductile cast iron inside.

Compound
2.8…3.6% carbon and reduced silicon content
–0,5…0,8 %.
Properties
They have high surface hardness (950…1000
HB) and very high wear resistance.

Application Used for the manufacture of rolling shafts, wagon wheels with bleached rims, balls for ball mills. For the manufacture of

parts operating under conditions
abrasive wear, white cast irons are used,
alloyed with chromium, chromium and manganese, chromium and
nickel. Castings from such cast iron are characterized by high
hardness and wear resistance.
For parts operating under wear conditions at high
temperatures, use high-chromium and
chromium-nickel cast iron. Heat resistance achieved
alloying cast irons with silicon (5…6%) and aluminum (1…2
%). Corrosion resistance is increased by alloying
chrome, nickel, silicon.
Can be used for cast iron heat treatment.

Cast iron marking

KCh30-6
MF15

Gray cast iron is marked with the letters SCh with the addition of a number that indicates the tensile strength of cast iron. For example: MF15 MF - gray

Gray cast iron is marked with the letters SCh with
by adding a number that indicates
tensile strength of cast iron at
stretching.
For example: SC15
MF - gray cast iron;
15 - tensile strength
σv=150MPa.

Malleable cast iron is marked with the letters КЧ and numbers. The first two digits indicate the tensile strength, and the second elongation

Malleable cast iron is marked with the letters КЧ and
numbers. The first two digits indicate
tensile strength, and
the second elongation at
stretching.
For example: KCH30-6
KCh - malleable cast iron;
30 - tensile strength
σv=300MPa;
6 - elongation at
stretching δ=6%.

Ductile iron is marked with the letters HF and numbers. The first two digits indicate the tensile strength, and the second relative y

Ductile iron is marked
HF letters and numbers. First two
The numbers indicate the tensile strength
stretching, and the second relative
tensile elongation.
For example: VCh35-22
VCh - high-strength cast iron;
35 - tensile strength
σv=350MPa;
22 - elongation at
stretching δ=22%.

Grades of gray cast iron for castings used in the main branches of engineering

Industry
mechanical engineering
Purpose of castings
Cast iron grade (according to GOST 1412 - 70)
Automotive industry
Gearboxes, intake and exhaust pipes, flywheels
Cylinder blocks
mid 15-32
mid 18-36 mid 24-44
cylinder heads
midrange 21-40; MF 28-48
cylinder liners
MF 21-40
Press beds, hydraulic cylinders
SCH 32-52
Machine beds, marking plates,
hydraulic cylinders, valves
MF 21-40
Machine bases, skids, tables
mid 18-36
Troughs, faucets, bases, plates
MF 00
Small and medium non-responsible castings
mid 15-32
Exhaust pipes, flywheels,
foundation frames, crankcases, covers
working cylinders, blocks and others
critical castings
MF 21-40
Tractor building
Machine tool industry
Diesel building

CONTROL QUESTIONS

1. What alloys are cast irons?
2. What groups are cast irons divided into?
2. What shape can graphite have?
3. What property does graphite give to cast iron?
4. What are the properties of gray cast iron?
5. What cast irons are called chilled?
6. Why is white cast iron of limited use?
7. How are cast irons marked?

Homework

, p.80-87
Create a presentation.
Presentation Topics:
modified cast irons.
Anti-friction cast irons.
Influence of carbon on the properties of cast irons.

Bibliography

1 Nikiforov V.M. Technology of metals and construction materials.
- M .: Mashinostroenie, 1987
2 Handbook of the machine builder. In 6 volumes. T. 6 / Under the editorship of E.A. Satel. - 3rd
ed., corrected. and additional – M.: Mashinostroenie, 1964. 540 p. ill.
3 http://mashinostroenie.3dn.ru/publ/materialovedenie/chuguny/25-1-0-27
4 http://do.gendocs.ru/docs/index-208591.html?page=4#5480651

White cast iron White cast irons are characterized by the presence of carbon in the form of cementite (Fe 3 C). White cast iron is characterized by: high hardness brittleness high wear resistance Generally white cast iron is not machined and is used for conversion into malleable cast iron.

Properties of gray cast iron Gray cast iron has high casting properties and is well processed by cutting. Widely used in mechanical engineering. For increase mechanical properties gray cast iron is modified by adding aluminum or calcium.

Anti-friction cast iron Anti-friction cast irons are produced on the basis of gray, ductile and ductile cast irons. AChS cast irons are alloyed with: chromium (0.2-0.4%), nickel (0.2-0.4%), copper (0.3-2%), aluminum (0.4-0.8%). AChV cast irons are alloyed with: copper (0.7%), magnesium (0.03%). AChK cast irons are alloyed with: copper (1-1.5%).

Heat-resistant cast iron By introducing alloying elements cast irons are created with special physical and chemical properties. Heat-resistant cast iron is designed for operation at temperatures up to 600 ° C. Alloyed with nickel, chromium, manganese. Heat-resistant cast iron is used for the manufacture of parts gas turbines, pumps, internal combustion engines.

Marking of heat-resistant cast irons The designation of the grade of heat-resistant cast iron includes: the letter H (denoting "cast iron"); letters H, X, G (indicate alloying elements nickel, chromium, manganese); the letter Ш (indicates that graphite has a spherical shape); numbers behind the letter (indicate the percentage of alloying elements).

Heat Resistant Cast Iron Heat resistant cast iron has the ability to resist oxidation at elevated temperatures. Alloyed with chromium, silicon, aluminum. Heat-resistant cast iron retains its properties at temperatures up to °C.

Marking of heat-resistant cast irons The designation of the grade of heat-resistant cast iron includes: letters ZHCH (denoting "heat-resistant cast iron"); letters X, C, Yu (denote alloying elements chromium, silicon, aluminum); the letter W (indicates that the graphite has a spherical shape); numbers (indicate the percentage of alloying elements).

Marking of corrosion-resistant cast irons The designation includes: the letter Ch (denoting "cast iron"); letters X, T, M, D, H (denote alloying elements chromium, titanium, molybdenum, copper, nickel); the letter Ш (indicates that graphite has a spherical shape); numbers (indicate the percentage of alloying elements).

3. White cast iron contains carbon in the form of: a) cementite; b) nodular graphite; c) lamellar graphite.

34

slide presentation

Slide text: Topic: "Cast irons. Classification of cast irons"

Slide text: 1. Fluidity - the ability of metals and alloys in the molten state to fill the cavities of the mold (+) 2. Crystallization is the transition of a metal from a solid state to a liquid state (-) 3. Creep - the ability of a material to slowly and continuously plastically deform .... (+) 4. Malleability - the ability of metals and alloys to undergo various methods machining and cutting tools. (-) 5. Shrinkage - the ability of metals and alloys to shrink after solidification. (+) Blitz survey

Slide text: Cast iron is an alloy of iron and carbon, the carbon content is more than 2.14%.

Slide text:

Slide text: USEFUL HARMFUL IMPURITIES MANGANESE - increases the hardness of cast iron SILICON - increases strength and toughness, improves casting properties .. SULFUR - reduces strength, worsens casting properties PHOSPHORUS - increases brittleness

Slide text: depending on the degree of graphitization, which determines the type of fracture, - into gray, white and half (or bleached); depending on the form of graphite inclusions - for cast iron with lamellar, spherical (high-strength cast iron), vermicular and flaky (ductile cast iron) graphite; depending on the purpose - for structural and cast iron with special properties; By chemical composition- for alloyed and unalloyed. Classification and properties of cast iron.

Slide text: Classification of cast irons: 1. By structure: 1) Primary cast iron - white or pig iron (c \u003d 3.7% - 4.5%) Fe3C - cementite for steel production. 2) Gray or cast iron. brand: SCH - 15 Marking of gray cast irons: Letters SCh - (denoting gray cast iron) Numbers - tensile strength, kgf / mm2; Example SC - 18 - Gray cast iron, 18 - - tensile strength, 18 kgf / mm2;

Slide text: 3) Ductile cast iron KCh - 40 - 10, KCh 40-20 Marking of ductile irons: Letters KCh - (indicate ductile iron) Numbers - (1 - number - tensile strength, kgf / mm2, 2 - relative elongation, %) Example CN - 35 - 10 - Ductile iron, 35 - tensile strength, 35kgf / mm2, 10 - relative elongation, 10%)

Slide text: 4) Ductile cast iron VCh-35 Marking of ductile irons: Letters VCh - (indicate ductile iron) Numbers - (1 - number of tensile strength, kgf / mm2, 2 - relative elongation,%) Example VCh - 42 - 12 - Ductile iron, 42 - tensile strength, 35kgf / mm2, 12 - relative elongation, 10%)

Slide #10

Slide text: 5) Anti-friction cast iron - obtained on the basis of gray, ductile and ductile cast irons. Marking of anti-friction cast iron: The letters АЧ– (indicate anti-friction cast iron) Numbers - grade number according to GOST Example AChS - 2, anti-friction gray cast iron, 2 - grade number according to GOST.

Slide #11

Slide text: X - CHROME; D - COPPER T - TITANIUM M - MOLYBDENUM N - NICKEL U - ALUMINUM C - SILICON G - MANGANESE F - VANADIUM 6) Alloyed cast irons - cast irons into which special elements are introduced to improve the properties of cast irons.

Slide #12

Slide text: ChN 1KhMD - alloyed cast iron, nickel content - 1%, molybdenum and copper content - up to 1.5%

Slide #13

Slide text: What is the name of cast iron, in which carbon is contained in the form of cementite? What is the name of cast iron obtained by slow cooling? What is the name of cast iron with spherical inclusions? What cast iron is converted into steel? What is the name of cast iron obtained by annealing? What is the name of cast iron, in which carbon is in the form of graphite plates? What is the name of the cast iron obtained as a result of modification? What is the name of cast iron with graphite in the form of flakes? Which cast iron has high casting properties? Which cast iron has high ductility? Answer form: a combination of the question number and the letter of the answer. Answer options: a) gray b) white c) malleable d) high-strength

Slide #14

Slide text: 1.b 2.a 3.d 4.b 5.c 6.a 7.d 8.c 9.a 10.c Answers:

Slide #15

Slide text: 1. Cast iron Timber transportation by river 2. Metal Main component of cast iron 3. Non-metal Undesirable component of cast iron Crossword "Association"

Slide #16

Slide text: 4. Alloy additives Alloys of iron with silicon, manganese 5. Alloying element Leather 6. Non-metal in cast iron Component rock

Slide #17

Slide text: 7. Non-metal The main component of cast iron 8. Alloying element Outstanding personality 9. Alloying element Forest

Slide #18

Slide text: Message: “Cast irons used in mechanical engineering” Learn the classification of cast irons and their marking. Homework.

Blitz survey 1. Fluidity - the ability of metals and alloys in the molten state to fill the cavities of the mold (+) 2. Crystallization - the transition of a metal from a solid state to a liquid state (-) 3. Creep - the ability of a material to slowly and continuously plastically deform .... (+) 4. Malleability - the ability of metals and alloys to be subjected to various methods of machining and cutting tools. (-) 5. Shrinkage - the ability of metals and alloys to shrink after solidification. (+)

Classification and properties of cast iron. depending on the degree of graphitization, which determines the type of fracture, - into gray, white and half (or bleached); depending on the form of graphite inclusions - for cast iron with lamellar, spherical (high-strength cast iron), vermicular and flaky (ductile cast iron) graphite; depending on the purpose - for structural and cast iron with special properties; by chemical composition - into alloyed and unalloyed.

Classification of cast irons: 1. By structure: 1) Primary cast iron - white or pig iron (c \u003d 3.7% - 4.5%) Fe3C - cementite for steel production. 2) Gray or cast iron. brand: SCH - 15 Marking of gray cast irons: Letters SCh - (denoting gray cast iron) Numbers - tensile strength, kgf / mm2; Example SC - 18 - Gray cast iron, 18 - - tensile strength, 18 kgf / mm2;

3) Ductile iron KCh - 40 - 10, KCh 40-20 Marking of ductile irons: Letters KCh - (indicate ductile iron) Numbers - (1 - number - tensile strength, kgf / mm2, 2 - relative elongation,%) Example KCh - 35 - 10 - Ductile iron, 35 - tensile strength, 35kgf / mm2, 10 - relative elongation, 10%)

4) Ductile cast iron VCh-35 Marking of ductile irons: Letters VCh - (indicate ductile iron) Numbers - (1 - number of tensile strength, kgf / mm2, 2 - relative elongation,%) Example VCh - 42 - 12 - Ductile iron , 42 - tensile strength, 35kgf / mm2, 12 - relative elongation, 10%)

5) Anti-friction cast iron - obtained on the basis of gray, high-strength and malleable cast irons. Marking of anti-friction cast iron: The letters АЧ– (indicate anti-friction cast iron) Numbers - grade number according to GOST Example AChS - 2, anti-friction gray cast iron, 2 - grade number according to GOST.

Answer form: a combination of the question number and the letter of the answer. Answer options: a) gray b) white c) malleable d) high-strength What is the name of cast iron, in which carbon is contained in the form of cementite? What is the name of cast iron obtained by slow cooling? What is the name of cast iron with spherical inclusions? What cast iron is converted into steel? What is the name of cast iron obtained by annealing? What is the name of cast iron, in which carbon is in the form of graphite plates? What is the name of the cast iron obtained as a result of modification? What is the name of cast iron with graphite in the form of flakes? Which cast iron has high casting properties? Which cast iron has high ductility?

Cast iron is an iron-carbon alloy with a carbon content of >2.14% and impurities in tenths of a percent. In addition, cast iron contains impurities in tenths: silicon, manganese, sulfur, phosphorus, etc. In order to improve the properties, alloying elements such as chromium, nickel, copper, etc. can be introduced into cast irons.

Types of cast iron

Gray cast iron Gray cast iron is an alloy of iron, silicon (from 1.2-3.5%) and carbon, also containing constant impurities of Mn, P, S. In the structure of such cast irons, most or all of the carbon is in the form of lamellar graphite. The fracture of such cast iron due to the presence of graphite has a gray color. Gray cast iron is used for the manufacture of lightly loaded parts operating in light conditions. For example, gearbox housings, pumps, electric motors, various covers, heating batteries, etc.

White cast iron White cast iron is cast iron in which carbon is chemically combined with iron. Carbon in white cast iron is in the form of cementite Fe3C - a bound state. Cementite gives the cast iron fracture a shine, while graphite gives it a gray color. Therefore, cast iron, in which all carbon is in a bound state, is called white cast iron. Relatively soft and machinable. Softness gives free carbon.

Ductile iron Ductile iron is obtained by long-term annealing of white cast iron, which results in the formation of flaky graphite. The metal base of such cast iron: ferrite and less often perlite. Malleable cast iron got its name from its increased ductility and toughness (although it is not subjected to pressure treatment). Ductile iron has high tensile strength and high impact resistance. Parts of complex shape are made from ductile iron: rear axle housings of cars, brake pads, tees, squares, etc.

Ductile iron has nodular graphite in its structure, which is formed during the crystallization process. Spheroidal graphite does not weaken the metal base as much as lamellar graphite, and is not a stress concentrator. In cast iron, part of the carbon (more than 0.8%) is contained in the form of cementite. The structural components of such cast iron are perlite, ledeburite and lamellar graphite. Ductile Iron, Half Cast Iron

Cast iron is widely used in the manufacture of products for various purposes. The main qualities of cast iron are low cost, good casting qualities, strength and hardness. Cast iron is used where it is necessary to obtain parts of complex shape and sufficient strength. For example, machine beds, body parts or artistic cast-iron fences. Everyone is well aware of the artistic decorations of the embankments of St. Petersburg, made of cast iron. The openwork cast gates of the Winter Palace, as well as other monuments, are no less beautifully decorated. Scope of cast iron

In the automotive industry, cast iron is used to produce cylinder blocks for internal combustion engines (on modern production Compacted graphite iron is used), as well as crankshafts of diesel engines. Cast iron is widely used in plumbing equipment- cast iron is used to make bathrooms, sinks and kitchen sinks, as well as heating radiators, pipes and fittings. For example, cast iron bathrooms are highly valued by connoisseurs for their reliability, durability and unpretentiousness in operation. Such bathrooms can serve for decades, keeping the original look unchanged.