Cold Working Brass: Effects on Hardness & Microstructure Abstract The purposes of this lab were to determine a relationship between percent cold working and hardness, determine the effect cold working has on microstructure, and last but not least relate dislocation theory to the observed data. Determining the relationship between percent cold working and hardness involved using a cold roller and running our cartridge brass (70 wt.% Cu, 30 wt.% Zn) sample through it until the percent given was reached by each group. This is a good material because it is well suited to cold-forming because of its high strength and ductility. Each group was assigned a specific percent to reach. The percent’s were 0, 10, 20, 30 40, and 50 respectively. After our percent was given a top and bottom were decided and this was so the sample was ran through the same way every time. The percent cold work is found using this equation % CW = t1-t2/t1 * 100, multiplying by 100 to get the percent, t1 is the original thickness of the sample and t2 is the thickness after running it through. Introduction …show more content…
If work-hardening is performed at elevated temps it is said to be hot-worked. In contrast cold-working is done right around room temperature. In both situations the work hardening increases the strength and hardness because of plastic deformation. This causes atoms in a crystal to become disordered, which means that the atoms have moved into a disordered structure. This then raises the strength and hardness by impairing the easy movement of dislocations. Cold working was done at first along with harness testing, once familiarized with all of this testing relationships between hardness, microstructure, and degree of work hardening of brass were
The purpose of this lab was to calculate the specific heat of a metal cylinder
heat will stay in the cup and can only escape by rising to the surface
A Comparison of the Laboratory and Industrial Processes When going through the process of fermentation in a laboratory they use certain methods to achieve their goals and some of the methods that they use are completely different from the ones that are used in the industry of fermentation. A fermenter is a container that maintains optimum conditions needed to grow a particular organism I will be using different criteria’s to compare the laboratory and industrial process of fermentation in this assignment; some of them are listed below: * Equipment Used * The Quantity of the Product * Method Used * Quality of the Product Before I get right on into the assignment I will firstly talk about penicillin is and what it is used for today in our society because penicillin will come up. Penicillin was discovered by Alexander Fleming in 1929 and penicillin is one of the earliest discovered and widely used antibiotic agents, derived from the penecillium mold and the use of penecillium did not begin until the 1940s. Penicillin kills bacteria by interfering with the ability to synthesis the cell wall and this will disallow it from splitting and reproducing and it will only lengthen longer Below are is a table that shows the most obvious differences in fermentation in a laboratory and fermentation in the scientific industry: Laboratory Fermentation: Industry Fermentation: It is a batch culture They use a Ph sensor The Ph level is not being controlled The equipment used is more expensive The temperature is not being measured They use a thermometer The yeast population isn’t been given O² They equip the fermenter with an exit gas and an exit liquid flow The food supply is not being replenished They also equip it with a antifoam and gas flow It also has a dissolved O² sensor Equipped with an Sparser In industry they have a fresh media feed
The micro hardness of the prepared samples were obtained by using a Vickers Micro hardness Tester (Model : Leco LV 700, USA). 5 readings were taken for each sample to calculate the average hardness. An indentation load of 5gf was used. After calculating the average hardness for each sample, mean variance and standard deviation (S.D.) was calculated to check the consistency of the data.
The process was first used at NASA to weld super lightweight external tank foe the Space Shuttle. Today FWS is used to join structural components for Delta IV, Atlas IV and Falcon IX rockets as well as the Orion Crew Exploration Vehicle. A current focus of FSW research is to extend the process to new materials which are difficult to weld using conventional fusion techniques. Since FSW occurs below the melting point of the work piece material, hence the deleterious phase is absent here. FSW characterizes the effect of process parameters such as spindle speed, traverse rate, length of joint on the wear
Bryson, William E. Cryogenics. Book News, Inc.1999 Aimed at a non-scientific business audience, this book explains some of the cryogenic processes that may be used to improve wear and stress performance of metal and other materials.
The metal’s hardness along with its great tensile strength and ability to withstand extremely high temperatures make it ideal for use in the filaments in incandescent light bulbs, cathode-ray tubes, X-ray tubes, vacuum tube filaments, and rocke...
In Friction stir welding process melting does not occur and joining takes place below the melting temperature of the material. Frictional heat is generated between the wear-resistant welding tool and the material of the workpieces. This heat causes the workpieces to soften without reaching the melting point and allows the tool to traverse along the weld line. Defect free copper welds are achieved by friction stir welding carried out at a constant welding speed of 100 mm/min.[1]. The effect of various input speed on microstructure and mechanical properties of friction stir welded Cu–30Zn brass alloy is investigated [2]. Friction stir welding of 5mm thick pure copper plates were done. The characteristics of the microstructure, different heat zones and mechanical properties of welded joints are investigated [3]. The temperature distributions of the weld, Brinell's hardness test, tensile test and microstructure analysis are performed on the welded aluminium alloy
Strain hardening is the additional stress required to cause slip in a material. It occurs when dislocations in a crystal interact with each other or when the dislocations observe hindrance in their motion. Either dislocations pile up at the barriers of slip plane of crystal or they intersect other dislocations. The latter can result in jogs which restrict its motion. Jogs readily occur in the cases of screw dislocations which cases to restrict the dislocation movement thus increasing strain hardening but not so in case pf edge dislocation. The strain hardening or work hardening behavior for FCC, BCC and HCP can be observed by taking the case of Iron, copper and magnesium where iron is BCC, copper is
HOT FORGING - Hot forging is defined as working a metal above its re-crystallization temperature. The main advantage of hot forging is that as the metal is deformed the strain-hardening effects are negated by the re-crystallization process.
This usually happens when a material has undergone a process in which the material becomes more brittle and is less able to plastically deform. These processes include cold working or precipitation hardening.
The mechanical property of ductility is quantified by the fracture strain〖 ε〗_f, which is the strain the material fractures when increasing tensile stresses are applied along a single axis. The reduction of the area from the initial point to the fracture during the test can also be considered as a measure.
At the point when metallic working materials are bowed in icy condition (underneath their recrystallization temperature), at initial a flexible shape modification happens, which is supplanted by a pliable shape adjustment from find out degree on. In the event that the reshaping limit is keep running down, the work piece breaks. Bowing is an essential stride during the time spent assembling mechanical pipes and tubing, which serve an imperative part in both development and the transportation of materials. Most bowed pipes and tubes work as auxiliary parts or as "way" units that encourage the exchange of
WEDM process can be applied to all electrically conducting metals and alloys irrespective of their melting points, hardness, toughness or brittleness.
Bish (2009) conducted a study on the effects of single-step austempering heat treatment and the addition of alloying copper of NCI to the hardness, tensile strength. The study w...