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MMET-207 Exam 2
| Question | Answer | Answer 2 |
|---|---|---|
| Do metal, plastics, & ceramics corrode? | Yes | |
| Requirements for electrochemical corrosion: | electrolyte, battery (voltage), anode, cathode, electron flow. | |
| The electrolyte in elevated temperature oxidation is | oxidation product. | |
| anion | Ion w/ negative charge | |
| cation | Ion w/ positive charge | |
| Ferrous Rusting | 2Fe(OH)_2->Fe_2O_3*3H_2O | |
| Oxidation requires | electron interactions, high temperature, water | |
| Reduction requires | aqueous solution, reduced free energy | |
| Why do stainless steels resist corrosion in many environments?Stainless steel is an alloy of iron... | and copper along with iron and carbon. It also has nickle and chromium. The nickle and chromium for a small layer on the stainless steel that does not dissolve in water. This keeps the stainless steel free from the air and its does not get rusted. | |
| Which of the following is most likely to exacerbate (make worse) corrosion of materials? | a tensile stress | |
| Which of the following has the best resistance to reducing environments? | zirconium alloys | |
| Polorization | The development of regions of low chemical activity in a chemical cell. | |
| How do you obtain uniform corrosion? | Electrochemical reactions. | |
| Which of the following are NOT "types" of corrosion? | galling | |
| How is galvanic corrosion dealt with? By choosing two best close metals from the galvanic series, since closer materials have lesser potential difference and constitute less galvanic current.... | By considering the relative size of the electrodes; if the size of the anode is larger compared to cathode, then the potential for corrosion will be low, & keeping metals unmixed when immersed in an electrolyte. | |
| What is the mechanism of crevice corrosion? | Crevice corrosion represents local attack in the revise between two surfaces that can be either metal-metal or metal-nonmetal surfaces. One crevice must be exposed while the other is in the crevice | changes in corrodent chemistry/electrochemical activity in the crack areas. |
| What can be done to prevent SCC (stress corrosion cracking)? | Choose the material by comparing the corrosion data, Control the environment so that the environment responsible for the problem is reduced or removed, & Achieve control of stress by reducing or removing the stress present in the material. | |
| Which of the following is NOT a form of erosion? | scuffing | |
| Plastic corrosion includes all of the following EXCEPT: | galvanic corrosion | |
| Corrosion characteristics of engineering materials is determined by: | free energy data sheets | |
| Which of the following is NOT a standard corrosion test for metals? | FTIR | |
| Which of the following is NOT a corrosion/environmental resistance test for plastics? | roof rack | |
| Cathodic protection | By using galvanic corrosion. an electrochemical process used to prevent corrosion of metal surfaces | By using galvanic corrosion. an electrochemical process used to prevent corrosion of metal surfaces |
| Anodic protection | A passive layer is formed around the metal to be free from corrosion. Applied on vessels and chemical equipment | |
| Which of the following materials is resistance to attack by acids? | polytetrofluoroethylene | |
| How can the corrosivity of aqueous environments be reduced? | By controlling CO2 content, H2S content, oxygen and oxidizing agents, acidity, ph, and others | |
| What attacks aluminum oxide & silicon carbide? | Aluminum oxide is attached by wet fluorine, hydrofluoric acid, phosphoric acid, high temperature and Silicone carbide is attached at a temperature of 1600 C | |
| 4 ways that crevice corrosion can be mitigated. | 1. Prevent the entry of moisture 2. Cathodic protecting 3. Employing alloys which are less affected by crevice corrosion 4. Addition of inhibiting substances to bulk solution | |
| Can you fasten aluminum siding w/ stainless steel nails w/out a corrosion concern? | No | |
| How can photoytic decomposition of plastics be reduced? | Photolytic decomposition in plastics is the effect of UV rays from sunlight. It is reduced by adding suitable anti ultra violet substances before shaping molding process | Reduce sunlight & nanotechnologies (nanoparticles & nanocomponents). |
| How is SCC of stainless steel controlled? | How SCC of stainless steel controlled? By removing chloride from water by ion exchange process, lowering potential, removing tensile stresses, handling below threshold temperature | stress relieving/operating stress level are low. |
| What can be done to address corrosion of stainless steels by seawater? | Instead of using austenitic stainless steel in seawater, superferritic stainless steel can be used. Also by adding chromium and molybdenum to stainless steel | Good gasketing & avoid gasketed faying surfaces & surface deposits. |
| How is sensitizing of stainless steels provented? | 1. High temperature heat treatment b. By adding low carbon grades to minimize carbide creation 3. by adding titanium to fasten with carbon atoms | modify grades to low-carbon, & alloy stabilization. |
| A typical corrosion allowance for steel outdoors is: | 25 um/year | |
| How is biological corrosion addressed? | is produced by small living organisms such as bacteria, fungi and algae. | Biocides |
| Types of erosion: | Solid particle, slurry erosion, liquid impact, liquid erosion, cavitation, or slurry pumping, impingement, sand blasting, cavitation. | |
| Atomic Diffusion & what controls it | Atoms vibrate more the more the metal heats up. Atoms squeeze into spaces making the grains closer to each other. Temperature, microstructure, & diffusion mechanism/species. | |
| Diffusing species: Nitriding | Solute: N. Host: nitriding steels. Case Depth: 125-500, 12.5-25, 50, 25-75 micro-m | |
| Diffusing species: carbonitriding | Solute: C+N. Host: low-carbon steels | |
| Diffusing species: carburizing | Solute: C. Host: low-carbon steels. Case Depth: 25 micro-m | |
| Decarburization & why it is a concern | Decrease in C . Concern because C makes metals harder. The metals want that! | |
| White layer & prevention | Has Cs that like to bond w/ alloy nitrides. On the surface of metals. Prevention: copper plating, gas-nitriding, salt-nitriding, & plasma processes | |
| Corrosion | Corrosion is the gradual destruction or deterioration of materials (usually metals) due to chemical or electrochemical reactions with their environment. | |
| Problems Caused by Corrosion: | Structural failure, Reduced lifespan of materials and components, Increased maintenance and replacement costs, Safety hazards (e.g., pipeline leaks, bridge collapse), Contamination (e.g., corroded pipes contaminating water supply) | |
| Why Corrosion Occurs: | Metals tend to revert to their natural, more stable state (oxides, sulfides, or carbonates) due to thermodynamic instability in the presence of environmental factors such as oxygen, moisture, and chemicals. Electrochemical reactions drive the process. | |
| Galvanic Series Chart: | The Galvanic Series ranks metals based on their electrochemical activity in seawater. | |
| Anodic | Most active, more likely to corrode. Ex: Magnesium, Zinc, Aluminum, Steel | |
| Cathodic | Less active, more corrosion-resistant. Ex: Tin, Carbon/Graphite, Platinum | |
| Anode | The metal that loses electrons (oxidation), corrodes. | |
| Cathode | The metal that gains electrons (reduction), protected from corrosion. | |
| Active metals | corrode readily | |
| Passive metals | form a protective oxide layer (e.g. stainless steel, aluminum). | |
| Requirements for Corrosion to Occur: | Anode (metal losing electrons), Cathode (metal gaining electrons), Electrolyte (conducting medium like water, soil, or acids), Electrical connection (path for electron flow) | |
| Electrolyte | A liquid or solution that conducts electricity by allowing ion movement, facilitating electrochemical reactions. Examples: seawater, acids, moist soil. | |
| Electrochemical Corrosion | Metal atoms lose electrons (oxidation) at the anode and form metal ions, while electrons travel through the metal to the cathode, where reduction occurs. | |
| Galvanic Cell Components | Anode (metal that corrodes), Cathode (protected metal), Electrolyte (enables ion exchange), Electron flow through an external circuit | |
| Metallurgical Conditions Affecting Corrosion | Grain structure (fine vs. coarse grains affect corrosion resistance), Alloy composition (some metals resist corrosion better than others), Internal stresses (can create anodic/cathodic sites), Inclusions and impurities (can promote localized corrosion) | |
| Environmental Factors Affecting Corrosion: | Moisture and humidity (increase electrochemical reactions), Temperature (higher temperatures accelerate corrosion), pH levels (acids accelerate corrosion; alkaline environments can reduce it), | Oxygen availability (oxygen-rich areas often promote corrosion), Presence of salts, chemicals, and pollutants |
| How Operating Conditions Affect Corrosion: | Temperature variations can increase oxidation rates. Pressure changes may accelerate corrosion in pipelines and tanks. Flow rate (high fluid velocity can cause erosion-corrosion). Mechanical stresses (can lead to stress corrosion cracking) | |
| Uniform Corrosion | Even material loss across the surface. | |
| Galvanic Corrosion | Occurs when two dissimilar metals are in contact in an electrolyte. | |
| Pitting Corrosion | Localized corrosion forming small pits. | |
| Crevice Corrosion | Occurs in narrow spaces where stagnant solutions exist. | |
| Intergranular Corrosion | Occurs along grain boundaries in metals. | |
| Stress Corrosion Cracking (SCC) | Caused by tensile stress and a corrosive environment. | |
| Erosion Corrosion | Caused by fluid movement eroding the protective layer. | |
| Corrosion Fatigue | Repeated stress cycling weakens the metal in corrosive environments. | |
| Corrosion Allowance | Extra thickness added to materials to account for expected corrosion loss over time. | |
| Corrosion Rate Determination | Rate = (Weight loss × K) / (Density × Area × Time) ○ K = unit conversion factor ○ Expressed in mils per year (mpy) or mm per year (mm/y). ● Used to predict material lifespan and ensure safety and reliability. | |
| Types of Heat Treatments | Annealing, Normalizing, Hardening, Tempering, and Stress Relieving. | |
| Purpose of Annealing | softens metal, increases ductility, | |
| normalizing | Cool at room temp. | |
| stress relieving | Purpose: reduces residual stresses, Method: slow cooling, Effect: no change, Ex: welded parts, castings | |
| tempering | Reheating steel to reduce its toughness, undo hardness/brittleness from other processes | |
| hardening | Purpose: increases hardness & wear resistance, Method: rapid cooling (quenching), Effect: forms hard martensite, Ex: knives, high-strength parts. | |
| Stress relieving and its effects on material properties. | Annealing and stress leaving relieve stress by improving toughness and slow cooling . normalizing and tempering also increase toughness. hardening increases hardness and wear resistance, but decreases toughness. | |
| Stress Relieving | a heat treatment used to reduce internal stresses in materials without significantly altering their hardness or strength. | involves heating the material to a temperature below its critical point and then slowly cooling it.t helps to reduce residual stresses from welding, machining, or casting, improving the material's dimensional stability. |
| Hardening process: | Steels are heated to a high temperature (austenitizing) and then quickly cooled (quenching). | |
| Martensite | Hard, but brittle; formed by rapid quenching. | |
| Cementite | A hard and brittle iron carbide, typically found in high-carbon steels. Compound of iron & carbon Fe_3C. | |
| OQT (Optimum Quenching Temperature): | The temperature at which steel should be heated before quenching to achieve the best hardening results. | |
| Low Carbon Steel (OQT): | Typically results in a fine pearlite or ferrite microstructure when cooled from the OQT range. | |
| Hypereutectoid Steel (OQT): | (those with carbon content above 0.8%), the microstructure may contain cementite (Fe₃C) along with pearlite or martensite depending on cooling rates. | |
| Carbon (C) | Influences hardness, strength, and weldability. | |
| Manganese (Mn) | Improves strength, hardness, and wear resistance. | |
| Aluminum (Al) | widely used in steelmaking, primarily as a deoxidizer, grain refiner, and nitrogen scavenger. | |
| Sulfur (S) | an impurity in steel that can negatively impact its properties, but in controlled amounts, it can also enhance machinability. | |
| Phosphorus (P) | an element found in trace amounts in steel, and while it generally has negative effects, it can offer some benefits in certain situations. | |
| Silicon (Si) | in steel acts primarily as a deoxidizer, improving strength, heat resistance, and electrical properties, but excessive amounts can reduce ductility and weldability. | |
| Boron (B) | a trace element in steel that significantly enhances specific properties, particularly in terms of hardenability and strength, when used in very small amounts. | |
| Lead (Pb) | a soft, heavy metal that is primarily added to steel to improve machinability, though it has several other distinct effects. However, its use is limited due to environmental and health concerns. | |
| Chromium (Cr) | Increases hardness, wear resistance, and corrosion resistance. | |
| Copper (Cu) | an alloying element that is added to steel for a variety of purposes, including improving corrosion resistance, strength, and overall performance in specific environments. | not used as frequently as other alloying elements, it plays a crucial role in specific applications. |
| Nickel (Ni) | Enhances toughness, strength, and resistance to low-temperature embrittlement. | |
| Molybdenum (Mo) | Improves hardenability and high-temperature strength. | |
| Vanadium (V) | Improves strength and wear resistance. | |
| Carbon Equivalency | A method of determining the weldability of a steel alloy. Higher typically means more difficulty in welding, increased risk of cracking, and need for preheating or post-weld heat treatment. | |
| HSLA Steel (High Strength Low Alloy Steel) | Steel with low alloy content but higher strength than carbon steels. Used in structural applications. | |
| B Carbon Steel | (boron treated) Often refers to steels used in construction or high-strength applications, but check specific context in the course. | |
| H Carbon Steel | (hardened) Typically used for high-temperature applications and pressure vessels. | |
| Weathering Steel | Steel that forms a stable, protective oxide layer that prevents deep corrosion. | |
| Major Alloying Element | Typically contains copper (Cu), which improves corrosion resistance | |
| Heat Treating Processes | Annealing, Hardening, Spheroidizing, Martempering, Austempering, Tempering, Stress Relief, Normalizing | |
| Relationship Between Tempering Temperature and Material Properties: | As tempering temperature increases, hardness decreases, while tensile strength and toughness increase. Ductility improves with higher tempering temperatures. | |
| Flame Hardening | Uses an oxyacetylene flame to heat the surface and then rapidly cools. Commonly used on steels that require hard surfaces but tough cores. uses rapid cooling & is a Surfacing Hardening Method. | |
| Induction Hardening: | Uses electromagnetic induction to heat the surface and then quenches. ○ Typically used for high-strength steels and specific applications like gears and shafts. uses rapid cooling & is a Surfacing Hardening Method. | |
| Diffusion Treatments | high concentration to low concentration | |
| Conditions for Diffusion to Occur: | High temperature, controlled atmosphere, and time | |
| Elements Diffused | Carbon (carburizing), Nitrogen (nitriding), Boron (boriding). | |
| Process of Diffusion | At high temperatures, atoms of an alloying element diffuse into the surface of the metal, modifying its properties. | |
| Resulting Chemistries and Microstructures from Diffusion | The surface chemistry changes, creating hard, wear-resistant layers. | |
| Metals Treated w/ Diffusion | Steels and some alloys. | |
| Hardenability | The ability of steel to form martensite when cooled from high temperatures. Carbon limits hardness of martensite. Alloying elements facilitate formation. | |
| Factors Affecting Hardenability | Carbon content, Alloying elements, & Cooling rate | |
| Carbon content | Higher carbon content generally improves hardenability. | |
| Alloying elements | Chromium, manganese, molybdenum, and nickel increase hardenability. | |
| Cooling rate | Faster cooling rates improve hardenability. | |
| Common Quenching Mediums | Water, oil, air. | |
| Cooling Rates | Water cools fastest, oil is slower, and air is the slowest. | |
| Contact Quenching | Involves quenching materials by direct contact with a medium like water or oil. | |
| Grain Growth: | The increase in grain size due to prolonged exposure to high temperatures. (we keep the grains fine by fast cooling) | |
| Grain Growth effect | Larger grains reduce strength and hardness. | |
| Time-Temperature Transformation (TTT) Curves | TTT curves show the relationship between temperature, time, and the formation of different microstructures in steels. | Alloying elements can shift the critical temperatures and the transformation start and finish times, affecting the microstructure and properties. |
| Numbering System for Plain Carbon Steels | First two digits = primary alloying elements, last digit = carbon content in hundredths of a percent. | |
| Numbering System for Alloy Steels | Contains additional elements (e.g., chromium, nickel) and is designated by a specific series. | |
| Carbon Content Ranges of Low Carbon Steel | 0.05% - 0.30% carbon. Good formability and weldability. | |
| Carbon Content Ranges of Medium Carbon Steel | 0.30% - 0.60% carbon. Higher strength but lower ductility. | |
| Carbon Content Ranges of High Carbon Steel | 0.60% - 1.0% carbon. Hard and strong but less ductile. | |
| Categories of Tool Steels: | Tool steels are categorized based on their primary alloying elements and their applications. | |
| Water-hardening tool steels (W-Water) | Low alloy content, used for tools requiring moderate hardness. | |
| Cold-working tool steels (O-Oil Hardening, A-Air Hardening, D-High Carbon, High Chromium): | Medium to high alloy content, good for forming and cutting tools. | |
| Shock-resisting tool steels (S-Shock) | High toughness, used for tools that endure impact. | |
| High-speed steels (H-High Speed) | Excellent hardness retention at high temperatures, used for cutting tools. | for example, have high resistance to wear and maintain hardness at elevated temperatures, making them ideal for cutting tools. |
| Hot-working tool steels (P-Plastic Mold, L-Special Purpose): | Designed for use in high-temperature environments, such as forging dies. | |
| Tool Steels often contain | carbon, chromium, vanadium, molybdenum, tungsten, cobalt, and nickel to improve hardness, wear resistance, and heat resistance. | |
| Prefixes for Tool Steels: | The letter prefix indicates the category or intended use (e.g., A for cold-working steels, H for high-speed steels). The number represents specific alloys within the series. | |
| Hardening Characteristics of tool steels | Tool steels are selected for their ability to undergo hardening through heating and quenching processes. The hardening properties depend on the alloy content, cooling rate, and heat treatment processes used. | |
| eutectic structure | a mixture of two or more phases that form at a specific composition and temperature. It has a unique microstructure that can affect the material's properties, such as hardness and toughness. | |
| Severe Banding | occurs when the different phases (e.g., pearlite and ferrite) are unevenly distributed, leading to weak points in the material. It is undesirable because it can result in poor mechanical properties, such as reduced toughness and fatigue resistance. | |
| Characteristics for Hardening and Use: | Tool steels are selected for their ability to undergo hardenability, meaning they can form hard martensite during quenching. High-carbon content generally improves hardness, but may reduce toughness. | Alloying elements such as chromium, molybdenum, and vanadium improve wear resistance, heat resistance, and toughness. |
| What microstructure is produced by hardening 4340 steel? | It primarily forms martensite. Depending on the cooling rate, some residual austenite might also be present, but the dominant phase after quenching is martensite, a hard and brittle microstructure. | If tempered afterward, tempered martensite may form, which improves toughness while reducing brittleness. |
| What phases are present after 52100 steel has been raised above the Ac3, soaked for the appropriate time, then oil quenched? | the primary phase formed is martensite. The rapid cooling from the austenitizing temperature prevents the formation of pearlite or ferrite and transforms the austenite into martensite. | If the steel were tempered afterward, the microstructure would consist of tempered martensite. |
| A welded steel structure is raised to 1100°F and held for 1 hour per inch of thickness. What probably is being done to it? | The steel is likely undergoing stress relieving. Stress relieving involves heating the material to a temperature below the critical point, holding it for a specified period , and then allowing it to cool slowly. | This process reduces internal stresses that may have been introduced by welding or other manufacturing processes without significantly affecting the hardness or microstructure of the steel. |
| What is the result of heating a 1020 steel 50°F above the Ac3, soaking for the appropriate time, then furnace cooling? | 1020 steel is a low-carbon steel. When it is heated 50°F above the Ac3 (the upper critical temperature) and soaked, followed by furnace cooling, the steel will transform into a microstructure that is primarily pearlite and ferrite. | Since the cooling rate is slow (furnace cooling), it does not form martensite. The microstructure of pearlite (alternating layers of ferrite and cementite) and ferrite is characteristic of low-carbon steels when cooled slowly. |
| When should martempering be used? | when you want to reduce thermal stresses and distortion while still achieving martensite formation. It is typically applied to larger, thicker sections of steel to avoid cracking. The process involves quenching the steel in a medium to a temperature ... | ...just above Ms. holding it there to transform the austenite into martensite, and then cooling it to room temperature. This process results in martensite without the high stresses associated with conventional quenching. |
| When should Austempering be used? | when the goal is to produce bainite, a microstructure that offers a good combination of strength, toughness, and wear resistance. the steel is quenched from the austenitizing temperature into a bath held at a temperature between ... | ...Ms and Bs (the bainite start temperature). This process results in a microstructure of bainite instead of martensite, which has better toughness and is more resistant to cracking. |
| What is the result of spheroidizing a 1090 carbon steel? How would it be done? | Spheroidizing involves heating the steel to just below its Ac1 temperature (approximately 700–750°F) and holding it at this temperature for an extended period (several hours). | This allows the cementite to coalesce into spherical shapes, which results in a microstructure that is softer and more machinable. |
| What is the result of spheroidizing a 1090 carbon steel? Why is it done? | Spheroidizing is done to improve machinability by softening the steel and making it easier to cut or shape. It is also used to refine the grain structure, which can improve toughness and reduce brittleness. | |
| Eutectic networks | refer to the arrangement of these phases in a network-like structure within the material, which can impact its mechanical properties. | |
| 10xx carbon steel Series | Plain carbon steels, where the first two digits represent the type and the last digit indicates the amount of carbon in hundredths of a percent (e.g., 1010 = 0.10% carbon). | |
| 11xx carbon steel Series | Resulfurized and rephosphorized carbon steels, similar to the 10xx series but with improved machinability due to the added sulfur and phosphorus. | |
| 41xx, 43xx, 52xxx carbon steel Series | Alloy steels with specific alloying contents. | |
| 41xx carbon steel Series | Contains chromium (Cr) and molybdenum (Mo) as the primary alloying elements. Often used for automotive and industrial applications. | |
| 43xx carbon steel Series | 43XX is chromium, molybdenum, and nickel | |
| 52xx carbon steel Series | 52XXX is chromium | |
| What has hypereutectoid steel strength? | Pearlite 120 KSI & Ferrite 40 KSI | |
| What is heat treatment? | Used to change the mechanical properties of the material | |
| What does the effect of heat treatment depend on? | Composition & microstructure of material, degree of prior cold working, & rates of cooling & heating during heat treatment. | |
| Examples of annealing | machining & forming metals | |
| Method of annealing | Furnace cooling: Heat to specific range of temp, hold at that temp, then air/furnace cool. | |
| Effects of Annealing | larger grains, softer material, increases ductility & machinability, reduces hardness & strength, relieves residual stresses | |
| Annealing | Used for the restoration of a cold-worked/heat-treated alloy to its original properties. Cools at controlled rate. | |
| Purpose of normalizing | improves strength & toughness | |
| Methods of normalizing | Heating then air cooling | |
| Effects of normalizing | fine grain structure, higher strength & hardness & lower ductility than full annealing. | |
| Examples of normalizing | structural steel, gears | |
| Quenching | High cooling rate, FCC -> BCT | |
| Method of Quenching | Heating then rapidly cooling the material | |
| Effects of Quenching | Much higher strength & hardness & lower ductility than annealing/normalizing | |
| Effects of Tempering | Reduces brittleness & residual stresses, increases ductility & toughness; converts brittle martensite to tempered martensite, harder than stress relieving, increases toughness | |
| Method of Tempering | Air cooling | |
| Examples of Tempering | cutting tools, gears | |
| True or False? Nonferrous alloys & some stainless steels generally cannot be heat treated by techniques used for ferrous alloys. | True | |
| What are other methods for heat treatment for Nonferrous alloys & some stainless steels? | Solution treatment & precipitation hardening | |
| Solution treatment | Alloy is heated to 540C, then water/other quenched to cool; result is moderate strength & high ductility. | |
| Precipitation hardening | Alloy is reheated to an intermediate temp & held there for a period of time. Result is stronger & less ductile | |
| Results from hardening steels | formation of martensite, a very hard and brittle microstructure. For some steels, especially those with higher carbon content, cementite (Fe₃C) can also form along with martensite, leading to a mixture of both microstructures. | |
| Crystal Structure & Characteristic of Ferrite | BCC iron w/ carbon in solid solution. Soft, ductile, & magnetic | |
| Crystal Structure & Characteristic of Austenite | FCC iron w/ carbon in solid solution. Soft, moderate strength, & nonmagnetic | |
| 13xx carbon steel Series | Manganese | |
| 23xx carbon steel Series | Nickel | |
| 4130 Carbon Steel Chemistry | C, Mn, Cr, Mo | |
| 4140 Carbon Steel Chemistry | C, Mn, Cr, Mo. Not the same as 4340 Carbon Steel | |
| 4340 Carbon Steel Chemistry | C, Mn, Ni, Cr, Mo. Not the same as 4140 Carbon Steel | |
| Prefixes of Carbon Steel numbering system | E & X | |
| E Carbon Steel numbering system Prefix | Made in electric arc furnace | |
| X Carbon Steel numbering system Prefix | Composition caries from normal. Its modified. | |
| Suffix of Carbon Steel numbering system | H | |
| H | ||
| H Carbon Steel numbering system Suffix | Steel will meet certain hardenability requirements. Often means that carbon & alloy contents are at high end of acceptable range. | |
| Letters in middle of numbers in the Carbon Steel numbering system | B & L, XXBXX & XXLXX | |
| B Letter in the Carbon Steel numbering system | Steel w/ boron as an alloying element | |
| L Letter in the Carbon Steel numbering system | Steel with lead added - improves machinability & not weldable. | |
| Letters of Carbon Steel Unified Numbering | G & A | |
| G letter of Carbon Steel Unified Numbering | Carbon Steel | |
| A letter of Carbon Steel Unified Numbering | Aluminum | |
| Severe Forming uses? | Lower carbon steels | |
| Medium carbon steels | Give higher strength w/out heat treatment compared to lower carbon steel | |
| Free machining steels are | good for machinability | |
| Steels that are good for flame/induction hardening are? | 1040-1060 | |
| Steels that are good for through hardening & are difficult to weld are? | 1080-1095 | |
| Avoid welding steels containing | Sulfur over 0.06% & phosphorus over 0.04% | |
| What is Safety in Hardening? | Risk of damage from hardening (quench cracks). | |
| Depth of Hardening | Hardenability, through hardening | |
| Size change in hardening | Very important for design net part size change after hardening & tempering. A hardening characteristics. | |
| Tool Steel Properties | Resistance to decarburization & heat softening; toughness, machinability, & wear resistance | |
| Resistance to decarburization | Scale, oxidization of surface during heat treatment | |
| Resistance to heat softening | If enough heat is generated during operations that could cause tempering, softening of tool steals | |
| Toughness | All tool steels have little/no toughness, some are just worse than others | |
| Machinability | Difficult to quantify, very subjective | |
| Wear Resistance | Difficult to quantify, dependent upon specific application/wear criteria |
Created by:
Texi Rae
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