Heat treatment properties of 1 composition structure
2. Glossy, malleable, electrically and thermally conductive alloys
3. Heat treatment performance of components
Think about a problem
A: The tools, cutters, fixtures, measuring tools and workpieces used by mechanical workers are mostly metal materials, so I know the knowledge of metal materials and heat treatment. Use these tools correctly and reasonably in the work; According to the material characteristics, correctly and reasonably select and sharpen the geometric parameters of the tool; Select appropriate cutting parameters; It is very important to choose the right method to improve the process performance of parts.
Metal materials and heat treatment.
foreword
fill-in-the-blank question
Important guiding significance.
Chapter I Structure and Crystallization of Metals
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1. Amorphous crystal
2. Body-centered cubic face-centered cubic face-centered cubic face-centered cubic face-centered cubic face-centered cubic face-centered cubic face-centered cubic face-centered cubic face-centered cubic face-centered cubic face-centered cubic face-centered cubic face-centered cubic face-centered cubic face-centered cubic face-centered cubic face-centered cubic face-centered cubic face-centered cubic face-centered cubic face-centered cubic face-centered cubic face-centered cubic face-centered cubic face-centered cubic face-centered cubic face-centered cubic face-centered cubic
3. The interstitial vacancy of crystal defect replaces the subgrain boundary of edge dislocation grain boundary.
4. Disordered liquids and ordered solids
5. supercooling degree
6. Low cooling speed
7. Nucleation and growth
8. Strength, hardness and plasticity
9. Fix one crystal lattice to another.
10. Static impact alternation
1 1.
12. Internal resistance of material to external force
13. Different internal forces
14. Structure inside external shape
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Multiple choice
1.A
2. Industrial and Commercial Bank of China
3.B
Noun interpretation
1. A: Lattice is an imaginary space frame that reflects the arrangement law of atoms; The unit cell is the smallest geometric unit that can completely reflect the lattice characteristics.
2. A: A crystal consisting of only one grain is called a single crystal; A crystal composed of many small crystals is called polycrystal.
3. Answer: Elastic deformation refers to the deformation that can be recovered after the external force is removed; Plastic deformation refers to permanent deformation that cannot be recovered after external force is removed.
4. Answer: When a material is acted by an external force, in order to make it not deform, a force opposite to the external force generated inside the material is called internal force; The internal force per unit area is called stress.
Thinking and practice
1. There is a horizontal line on the cooling curve, which means that the temperature is constant during this time period. Crystallization is actually the process of atoms changing from high energy level to low energy level, so a certain latent heat of crystallization will be released during the crystallization process, which makes the crystallized metal in dynamic thermal balance, so the crystallization of pure metal is carried out at constant temperature.
2. The common methods of grain refinement in production are: increasing undercooling, adopting modification treatment and adopting modification treatment. After metal crystallization, the finer the grain, the higher the strength and hardness, and the better the plasticity and toughness, so it is of great practical significance to control the grain size of materials.
3.( 1) The grains of metal mold casting are smaller than those of sand mold casting.
(2) The grains cast into thin parts are smaller than those cast into thick parts.
(3) The grains with vibration during casting are smaller than those without vibration.
MSG, rock sugar, mica, salt and various metals are all crystals.
5. (omitted)
6. Repeated bending gradually hardens, and bending becomes more and more difficult until it breaks. The reason is that repeated bending increases the local plastic deformation of iron wire, resulting in deformation strengthening.
7. Yes. Because the process of chip separation during cutting is actually a process of intense extrusion and friction between the tool and the workpiece to be cut, in this process, both the machined surface and the chip will undergo plastic deformation, resulting in work hardening. The work hardening of the chip will make it difficult to discharge, and the work hardening of the machined surface will make the subsequent machining difficult.
Chapter II Properties of Metals
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1. Physical properties, chemical properties, mechanical properties, casting properties, forging properties, welding properties, cutting properties and heat treatment properties.
2. Static plastic deformation and fracture
3. Yield strength, tensile strength, relative strength
4. Yield strength (ReL) Conditional yield strength (Rp0.2)
5.3 1400N 53000N
6. Elongation of permanent deformation (a) Area shrinkage (z)
7.58% 76%
8.5 Carbide 7355.25 10~ 15 Brinell hardness 500
9. shock
10.ReL Rm HRC A Z αk R — 1
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Multiple choice
1.B
2.C
3.B
4.C
5.A
Noun interpretation
1. An index to measure the plastic deformation resistance of materials.
2. Indicators for measuring the fracture resistance of materials.
3. The ability of materials to resist local deformation, especially plastic deformation, indentation or scratches.
4. The ability of metal materials to adapt to different processing methods.
Thinking and practice
1. (omitted)
2.
Symbol of hardness value of commonly used hardness measurement methods for materials
Brinell hardness or Rockwell hardness of aluminum alloy semi-finished products, class B HBW or HRB
Ordinary hardened steel Rockwell hardness C HRC
Brinell hardness HBW of cast iron
Vickers hardness HV of surface nitrided layer
3. Solution: Because it is a circulating chain, the cross-sectional area of the chain.
s0 = 2(πD2/4)= 2×(3. 14×202/4)= 628(mm2)
Fm= Rm？ S0=300×628= 188400 (N)
Therefore, the maximum load that the chain can bear is188400 n.
4. Answer: The bicycle axle mainly bears torsional load and alternating load when working, so the materials used need high hardness and strength; The chain box of bicycle needs stamping, so the materials used need to have good plasticity and toughness.
5. Answer: Because the gear bears alternating load and the lathe guide rail bears static load. Therefore, gears are prone to fatigue damage.
Chapter III Iron-carbon Alloys
fill-in-the-blank question
1. Metal characteristics of other metals and nonmetals
Step 2: Stage
3. Solid solution metal compound mixture
4. interstitial solid solution replaces solid solution
5. Intrinsic melting point hardness brittleness of interacting metals
6. Ferrite austenite cementite pearlite ledeburite
7. Ferritic austenite
8. Plastic toughness, strength and hardness
9. Ferrite austenite cementite pearlite ledeburite
10.2. 1 1% 0.77%
1 1.
12.f A Fe 3c P Ld L′d
13.0.0218% ~ 2.11%hypoeutectoid steel, bainite, pearlite, secondary cementite.
14. Ferrite cementite
15. austenite cementite austenite pearlite cementite low temperature ledeburite
16.2. 1 1% specially added.
17. silicon-manganese-sulfur-phosphorus
18.0.25% 0.25%~0.6% 0.6%
19. Structural steel, medium carbon steel and high quality steel
20. High-carbon and high-quality tools
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Multiple choice
1.B
2.A
3.C
4.B
5.C
6.C
7.B
8.B
9.C
10.C A B
1 1.C
12.C D B
13.A
14.B
15.A
16.AB blood type
17.C
18. A, B, C and D
19. A, B, C and D
20.C
Noun explanation:
1. Eutectic transformation and eutectoid transformation
Eutectic transformation refers to the simultaneous crystallization of two different solid phases from liquid phase; Eutectic transformation is the simultaneous precipitation of two different solid phases from one solid phase.
2. Solution strengthening and work hardening
In the process of solid solution formation, the dissolution of solute atoms will distort the lattice of solvent, thus increasing the deformation resistance of alloy and improving the strength and hardness of metal materials, which is called solid solution strengthening;
Cold plastic deformation not only changes the shape of grains, but also increases the dislocation density and lattice distortion in grains, so that the strength and hardness of metals increase with the increase of deformation, while the plasticity and toughness decrease. This phenomenon is called "deformation hardening" or "work hardening".
3.08F—— High-quality carbon structural steel (boiling steel) with incomplete deoxidation, with carbon content of 0.08%.
4.45 —— High quality carbon structural steel with carbon content of 0.45%.
5.65Mn—— High-quality carbon structural steel with 0.65% carbon content and high manganese content.
6.t 12A- high quality carbon tool steel with carbon content of 1.2%.
7.ZG 340-640- Cast steel with yield strength not less than 340MP and tensile strength not less than 640MP.
8.Q235—A？ F—— Carbon structural steel (boiling steel) with yield strength not less than 235MP, quality grade A and incomplete deoxidation.
Thinking and practice
1. (omitted)
2.
The characteristic point indicates the temperature (℃) and carbon content (%).
The melting point of pure iron is 1538 0.
The maximum dissolution point of E carbon in γ-Fe is 1 148 2+0438+0.
Isomeric transition point of g pure iron α-Fe γ-Fe
9 12 0
C eutectic point, LC (A+Fe3C)
1 148 4.3
The eutectoid point is (F+ Fe3C)
727 0.77
D melting point of cementite 1227 6.69
Characteristic line meaning
ACD liquidus-Above this line is the liquid phase region, and the point on the line is the initial temperature of the alloy with the corresponding composition when it crystallizes.
ECF eutectic line, LC (A+Fe3C)PSK eutectoid line, also known as A 1 line. AS (F+ Fe3C)AECF solidus line —— Below this line is the solidus region, and the point on the line is the crystallization end temperature of the alloy with corresponding composition.
GS is also called A3 line. Initial line of ferrite precipitation in austenite with different carbon content during cooling.
ES is also called Acm line. Solubility curve of carbon in γ-Fe
3.
(1) According to the phase diagram, the proportion of hard cementite in steel increases with the increase of carbon content, so the hardness of iron-carbon alloy with 1% is higher than that of iron-carbon alloy with 0.5% carbon content.
(2) According to the phase diagram, when the steel is heated to 1000 ~ 1250℃, its structure is just in a single austenite state. At this time, the steel has good plasticity and low plastic resistance, which is most suitable for forging and rolling.
(3) From the phase diagram, the crystallization temperature range of Fe-C alloy close to eutectic composition is small, and the crystallization temperature is the lowest. Therefore, the fluidity is good and segregation is not easy to occur during crystallization.
4. no. Because their working properties are different, their stress conditions are different, and their processing technology is also different. So choose materials with different properties.
5. Because the basic phase in white cast iron is mainly cementite, it is hard and brittle to cut. Therefore, it can not be directly used as the material for processing parts, but the advantages of high hardness, durability and good abrasiveness can be well utilized by casting plows, ploughshares and other agricultural tools.
Chapter IV Heat Treatment of Steel
fill-in-the-blank question
1. Solid state heating, heat preservation and cooling all have isomorphic transformation of structural iron.
2. Annealing, normalizing, quenching, tempering, surface quenching and surface chemical heat treatment.
3. Forming grain growth
4. Heating temperature and holding time
5. Pearlescent bainite martensite type
6. The lower the temperature or the greater the undercooling, the higher the strength and hardness.
7. Upper bainite and lower bainite
8. 170 ~ 230 HBW normalizing annealing
9. The critical cooling rate V is close to Mf retained austenite.
10. Strength and toughness carbon content of high needle hard brittle plate
1 1. Oil, water, salt and alkaline water increase water and oil.
12. Single liquid quenching, double medium quenching, martensite step quenching and bainite isothermal quenching.
13. Diffusion carbon of carbon atoms in lattice of iron α-Fe interstitial solid solution
14. oxidative decarburization, overheating, deformation and cracking, insufficient hardness and soft spots
15. Tempering stabilized the structure and eliminated the internal stress.
16. Strength, hardness, plasticity and toughness Low temperature tempering, medium temperature tempering and high temperature tempering
17. Comprehensive mechanical properties of quenching and high temperature tempering
18. Flame heating surface quenching induction heating surface quenching electric contact surface heating quenching laser heating surface quenching
19. decomposition absorption diffusion surface carburizing surface nitriding surface carbonitriding
20. Final heat treatment in heat treatment preparation
Multiple choice
1.C
2.B
3.A
4.B
5.C
6.B
7.A
8.C
9.A
10.B
1 1.B
12.C
13.c？
14.C B
15.D B
16.C
17.c？
18.C
19.A
20.B
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Noun interpretation
1. A: The supersaturated solid solution of carbon in α-Fe is called martensite.
2. Answer: Austenite that is cooled below the A 1 line and has not been transformed is called undercooled austenite; Martensite transformation can not be completely carried out, and austenite that has not been transformed when the transformation stops after cooling below MS line is called retained austenite.
3. Answer: Annealing refers to the heat treatment process of heating steel to an appropriate temperature, keeping it for a certain time, and then slowly cooling (generally cooling with the furnace); Normalization refers to the process of heating steel to 30℃ ~ 50℃ above AC3 or Accm, keeping it at this temperature for a proper time, and then cooling it in the air.
4. Answer: The heat treatment process of heating steel to an appropriate temperature above Ac3 or Ac 1 and then rapidly cooling (cooling rate greater than V) after heat preservation to obtain martensite or lower bainite structure is called quenching; The heat treatment process of reheating the quenched steel to a certain temperature below Ac 1, keeping the temperature for a certain time, and then cooling to room temperature is called tempering.
5. Answer: Hardenability refers to the ability of steel to obtain the depth of martensite structure when quenching and cooling under specified conditions; Hardening ability refers to the highest hardness that steel can achieve after obtaining martensite under ideal quenching conditions.
6. Answer: Carburizing of steel refers to a chemical heat treatment process in which steel parts are heated and insulated in carburizing medium, so that carbon atoms penetrate into the surface layer of the workpiece, and its purpose is to increase the carbon content of the surface layer of steel parts; At a certain temperature, the chemical heat treatment process of infiltrating active nitrogen atoms into the workpiece surface is called nitriding. The purpose of nitriding is to improve the surface hardness, wear resistance, corrosion resistance and fatigue strength of parts.
Think about a problem
1. Answer: Twist drills made of tool steel usually achieve high hardness and high wear resistance through low-temperature quenching and tempering. If the grinding is not cooled in time, the hardness will be lost if the temperature is too high (annealing).
2. Answer: It can be completely annealed before forming to improve its plasticity, or it can be bent while heating to avoid cracks caused by work hardening during bending.
3. Answer: Normalization can eliminate stress, reduce hardness and improve cutting performance.
4. Answer: After rolling, the blank should go through the thermal mechanism of normalizing and spheroidizing annealing to eliminate the network cementite and reduce the hardness of the material, so as to facilitate the subsequent processing procedures; After processing and forming, the method of integral heating, local quenching and low temperature tempering of blades immersed in quenching medium is adopted to meet this requirement.
Chapter IV Alloy Steel
fill-in-the-blank question
1. Strengthen ferrite to form carbide, refine grain, improve hardenability of steel, and improve high tempering stability of steel.
2. Hardenability of cobalt stability at an appropriate critical cooling rate.
3. Gold structural steel alloy tool steel special properties steel alloy carburized steel alloy quenched and tempered steel alloy spring steel
rolling bearing steel
4. Hot-rolled annealed normalized structural parts
5. Carburizing+quenching+low temperature tempering to resist fatigue impact load
6. Complex stress and good comprehensive mechanical properties
7. Wear resistance of tools
8. Spheroidizing annealing quenching+low temperature tempering
9. Cutting tool steel, die steel and measuring tool steel
10.CrWMn low-speed tool
1 1. Red hard cutting speed is high and its shape is complex.
12. Cold working die steel
13. Hardness, wear resistance and corrosion resistance
14. Cr-Cr-Ni-Cr-Mn martensite ferrite austenite
15. Impact hardening
Multiple choice
1.B
2.C
3.A
4.A
5.A
6.B
7. Royal Airways
8. British government
9.A E B C D
10.B
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Noun interpretation
1. A: Low-alloy high-strength steel with yield strength not less than 460MP.
2. Answer: Alloy carburized steel with carbon content of 0.2% and chromium, manganese and titanium content less than 1.5%.
3. Answer: Alloy quenched and tempered steel with carbon content of 0.4% and chromium content less than 1.5%.
4. Answer: Alloy spring steel with carbon content of 0.5% and Cr and V content less than 1.5%.
5. Answer: Alloy rolling bearing steel with carbon content above 1% and chromium content above 1.5%.
6. Answer: Low alloy cutting tool steel with carbon content above 1% and chromium, tungsten and manganese content below 1.5%.
7.a: High speed steel containing 6% tungsten, 5% molybdenum, 4% chromium and 2% vanadium. ..
8. Answer: Large cold-working die steel with carbon content 1% and chromium content 12%.
9. Answer: Chromium stainless steel with carbon content of 0. 1% and chromium content of 13%.
10. A: Wear-resistant steel with manganese content of 13%.
Thinking about the problem:
1.
The final heat treatment method is mainly aimed at typical brands with different carbon contents.
Alloy carburized steel 0. 10% ~ 0.25% 20crmnti quenching+low temperature tempering speed change gear and cam.
Complex mechanical parts such as 0.25% ~ 0.50% 40Cr quenching and high temperature tempering spindle of alloy quenched and tempered steel.
Elastic parts such as alloy spring steel 0.45% ~ 0.70% 60 SIMN quenching+medium temperature tempering spring.
Rolling bearing steel 0.95% ~1.15% gcr15 quenching+low temperature tempering rolling bearing
High speed steel 0.7% ~1.50% w18cr4v
High-temperature quenching+multiple high-temperature tempering milling cutter, broach and other cutting tools with high cutting speed and complex shape.
0.3% ~ 0.6% 5 crmnmo quenching and medium temperature tempering of hot working die steel to make hot forging die.
Wear-resistant steel 0.9% ~ 1.4% ZGMN 13 water-tough crawler and other parts working under strong impact load.
2. Answer: 1Cr 18Ni9Ti is austenitic stainless steel with magnetism. Therefore, as long as magnets are used, two parts made of different materials can be easily separated.
Chapter VI Cast Iron
fill-in-the-blank question
1. More than 2. 1% cementite graphite
2. Graphitized austenite cementite
3. The size of the matrix morphology and quantity
4. Continuous casting performance, cutting performance, sound attenuation, shock absorption, pressure resistance and wear resistance of graphite.
5. Gray cast iron, white cast iron, hemp cast iron, gray malleable ball, flocculent spherical worm
6. Graphite annealing of white cast iron.
7. Distribution of quantity and morphology of graphite in the matrix.
8. Splitting heat treatment of ductile iron
Multiple choice
1.B
2. Binary-Analog Conversion.
3. ABC
4.A
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Noun interpretation
1. Answer: Gray cast iron with minimum tensile strength of 250MP.
2. Answer: Black-core malleable cast iron has a minimum tensile strength of 350MP and a minimum elongation of 10%.
3. Answer: Pearlite malleable cast iron has a minimum tensile strength of 500MP and a minimum elongation of 4%.
4. Answer: Ductile iron with a minimum tensile strength of 600MP and a minimum elongation of 4%.
Think about a problem
1.a: The process of carbon precipitation in cast iron in the form of graphite is called graphitization. The main factors affecting the graphitization of cast iron are the composition and cooling rate of cast iron. Generally, the higher the content of carbon and silicon in cast iron, the more graphite precipitated inside it and the larger the graphite flake. The slower the cooling rate, the more favorable it is for diffusion, thus making the graphite precipitate bigger and more sufficient.
2. Answer: Because the cast iron pan is generally thin and cools quickly after casting, the newly bought cast iron pan structure is often white cast iron, which is hard and brittle, so the sound is particularly harsh when cooking; However, after a period of time, due to long-term high-temperature heating and insulation, the cementite in its structure gradually decomposes into flocculent graphite, which becomes malleable cast iron, with reduced hardness and improved toughness. So the sound of cooking is no longer so harsh.
3. Answer: Gray cast iron contains a lot of flake graphite, which splits the matrix like tiny cracks, destroying the continuity of the matrix. Therefore, when cutting gray cast iron blank workpiece, it will not produce continuous strip or nodal chips, but will produce crumbling chips. This greatly reduces the friction between chips and tools, and reduces the generation of cutting heat. In addition, the graphite falling off during cutting has a good lubricating effect; If cutting fluid is added, the exfoliated graphite mixed with cutting fluid will also be brought into the cooling system of the machine tool and splashed on the moving surfaces such as the guide rail of the machine tool, thus aggravating the wear between the moving pairs and damaging the accuracy of the machine tool itself.
Chapter VII Nonferrous Metals and Cemented Carbides
fill-in-the-blank question
1. Nonferrous metals, nonferrous metals, copper, aluminum and titanium
2. Brass, bronze, brass, copper, brass, copper, bronze
3. Single-phase dual-phase single-phase hot and cold pressure processing dual-phase hot pressing processing
4. Corrosion-resistant instruments, chemical machinery and medical devices
5. Forging aluminum alloy casting aluminum alloy rust-proof aluminum hard aluminum super hard aluminum forging aluminum.
6. Isomorphic transformation of dense hexagonal cube.
7. Titanium alloy
8. Hardness, wear resistance, compression and bending toughness of powder metallurgy red with carbide metal binder
9. Tungsten, cobalt, tungsten, cobalt, titanium, tungsten, titanium and tantalum (niobium)
Multiple choice
1.B
2. BC after A.D.
3. Business English
4. BC
5. Developing countries
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Noun interpretation
1. Answer: No.2 industrial pure copper
2. Answer: Brass is processed by flexible pressure, and its copper content is 68%.
3. Answer: Lead brass with lead content 1% and copper content of 59% is pressure worked.
4. Answer: Cast tin bronze with lead content 1%, tin content 10% and the balance copper.
5. Answer: No.4 industrial pure aluminum.
6. A: No.4 ultra-hard aluminum.
7. Answer: No.65438 +0 cast aluminum-magnesium alloy.
8. Answer: Tungsten-cobalt cemented carbide with fine-grained cobalt content of 6%.
9. Tungsten-cobalt-titanium cemented carbide with 9.TiC content of 15%.
10. A: No.2 universal cemented carbide.
Thinking about the problem:
1. A: There are many non-ferrous metal products used in our life, such as aluminum pot, aluminum pot, aluminum doors and windows, titanium alloy spectacle frames and various non-ferrous metal decorations. Most of them have the characteristics of good corrosion resistance, beauty and portability.
2. A: No, because cemented carbide has good thermal hardness, but poor thermal conductivity. If it is cooled sharply during grinding, it will cause excessive internal stress and lead to cracking.