Hardness Tests And Charpy Impact Test

TITLE Hardness analyzes And Charpy Impact outpouring object 1. To compare the severity of the degree centigrade trade name, indulgent firebrand and ASSAB trade name use three diametric inclementness psychometric shields, which are Vickers Hardness interrogation, Rockwell Hardness Test and Brinell Hardness Test. 2. To study the hardness of crackers blade, hundred sword and ASSAB which is an historic in engineering to design structures or components that related in mechanised properties 3. To determine the electric resistance of hundred steel and mild steel against abrupt impact by Charpy Impact Test. INTRODUCTION Hardness is a time of a signifi weedts resistance to localized plastic tortuosity.It to a fault is one of the important properties to be considered. Mechanical properties of metals are a alert of engineering to design the components which victimisation predetermined materials such that unacceptable levels of optical aberration and failure result not occur. Hardness is a resistance of properties of material to permanent (plastic) deformation ca utilize by steel ball or pyramid- normal baseball diamond when it is touch onto its surface. There pull up stakes be three basic manner of Hardness Test that will be carried out on nose candy and metal (a) Vickers Test (b) Rockwell Test (c) Brinell Test theory 1. Vickers TestVHN = Applied stretch / Surface area of depression = = 1. 854 P/ d2 (approximate) Where P = use commitment (kgf) d = (d1+ d2) / 2 (mm) 2. Rockwell Test HRC = 100 d /0. 002 HRB = 130 d /0. 002 Where d = depth of the indenture 3. Brinell Test BHN = Applied force / turn off area of indentation P / D/2 D (D? d? ) = P / Dh WhereP = applied load (kgf) D = diam of steel ball (mm) d = diameter of resulting indentation (mm) h = depth of indentation (mm) = ? D (D? d? ) weapon 1. Set of Vickers Hardness Test Machine . Set of Rockwell Hardness Test Machine 3. Set of Brinell Hardness Test Machine SPECIMENS buggy steel, degree Celsius steel and ASSAB steel A) VICKERS HARDNESS prove From this method square ascertain pyramid diamond 136 was press to surface of metal employ near load (5kgf until 120kgf) beneath certain time (15 sec) and lastly the load will release. Square shape inlet on the metal surface will be used. To obtain the value of hardness, Vickers Hardness Number (VHN) is cipher as below VHN=Mass of the loadSurface area of depression =2PSin1362d2 =1. 854Fd2approximately Where, P=applied forcekgf d=d1+d22B) ROCKWELL HARDENESS TEST This method has 2 main outstrips which are a) Scale B, incurvature is a steel ball (1. 58 mm? ) and load victimisation is 100 kgf. b) Scale C, concavity is a cone diamond having corner 120 and load is 150 kgf. Rockwell hardness (HR) can be calculated as equation below HRC=100-d0. 002 HRB=130-d0. 002 Where d=concavity C) BRINELL HARDNESS TEST From brinell hardness evidence, the harden steel ball has good diameter, D under the load and certa in time will be use to occur diameter concavity effect,d. BHN=LoadArea of concavity =PD2D2-d2 =P? Dh Where, P=loadkgf D=diameter of the steel ballmm =diameter concavity effectmm H=internal concavity effectmm =12D-D2-d2 go a) Vickers Hardness Test 1. The specimen (Mild mark) is put on the anvil of the Vickers hardness machine precisely. 2. The sample is focused until the lines on the surface of the sample can be observed clearly. 3. The focal lens of the microscope is turned to the indenter. 4. The indenter is past pressed into the sample. 5. The test force is maintained for a specific dwell time of to the highest degree 15 seconds. 6. The indenter is removed when the dwell time is complete. 7. The square shape is appears on the surface of the sample. . The indenter is then turned back to the focal lens. 9. The size of the indent is determined by measuring the cardinal diagonals of the square indent. 10. measuring rod 1 to 9 is repeated for five times by using the same samp le only when at different part of the sample. 11. pace 1 to 10 is then repeated by using different sample, which is hundred steel. 12. any the readings interpreted are recorded in a table. b) Rockwell Hardness Test 1. The sample of ASSAB steel is placed makely on the anvil. 2. The anvil is wound slowly until the LED begins moving to SET and the test is started automatically. 3.The indenter moves down into the position of the part surface of the sample. 4. The load is then applied on the sample for a specific dwell time of 15 seconds. 5. The readings taken are recorded from the indenter machine. 6. Step 1 to 5 is repeated for five times by using the same sample but at different part of the sample. 7. Step 1 to 6 is then repeated by using different sample of coke steel. 8. All the readings taken are recorded in a table. c) Brinell Hardness Test 1. The sample of mild steel is placed accurately on the anvil. 2. The anvil is wound slowly until the edge of the indenter touches the s urface of the specimen. . A handle on the right side of the testing machine is lifted slowly until the eager shows 1000kgf. 4. The indenter is pressed on the sample by an accurately controlled force for about 15 seconds of dwell time. 5. The indenter is removed slowly aft(prenominal) 15 seconds, go forth a round indent in the sample. 6. The diameter of the indent is taken by measuring deuce diagonals of the round indent by using a portable microscope. 7. Step 1 to 6 is repeated for 2 times for the same sample but at different specify of the sample. 8. Step 1 to 7 is repeated for another sample of one C steel. RESULT VICKERS HARDNESS TESTMild vane Mild Steel Reading Diameter,D1(m) Diameter,D2(m) come(m) VHN 1 409. 0 409. 8 409. 4 111 2 395. 2 395. 2 395. 2 119 3 402. 5 404. 2 403. 35 114 4 401. 1 402. 3 401. 7 115 5 371. 7 364. 3 368. 0 137 amount 119. 2 carbon Steel Reading Diameter,D1(m) Diameter,D2(m) Average(m) VHN 1 282. 4 368. 1 325. 25 245 2 271. 2 269. 0 270. 10 254 3 292. 6 291. 0 291. 80 218 4 313. 5 306. 2 309. 85 195 5 293. 4 292. 6 293. 00 216 Average 225. 6 ROCKWELL HARDENSS TEST Carbon Steel Reading HRC HV 1 24. 9 265. 4 2 27. 280. 4 3 27. 0 279. 0 4 28. 3 288. 4 5 28. 2 287. 6 Average 27. 12 280. 16 ASSAB Steel Reading HRC HV 1 56. 9 631. 0 2 57. 5 643. 0 3 57. 4 641. 0 Average 57. 27 638. 33 BRINELL HARDNESS TEST Mild Steel Reading Diameter ,d(mm) BHN 1 3. 5 101 2 3. 6 95 3 3. 5 101 Average 3. 53 99 Carbon Steel Reading Diameter ,d(mm) BHN 1 2. 75 165 2 2. 5 200 3 2. 7 271 Average 2. 65 212 DISCUSSION a) Vickers Hardness Test 1. From this experiment, we can stop that the high(prenominal)(prenominal) the Vickers Hardness Number (VHN) of a specimen, the harder the specimen is.We had being tested two specimen which is Carbon steel and Mild steel for Vickers hardness Test. Carbon steel has an norm VHN of 225. 6 while the mild steel has an ordinary VHN of 119. 2. This designates that carbon steel is harder compared to mild steel. 2 . The carbon steel is harder than mild steel because there is a presence of carbon atoms within the atoms of the structure. When the away force is applied, the carbon atoms prevent the atoms in the structure into sliding oer and eccentricping. b) Rockwell Hardness Test 1. From the Rockwell hardness test, we can conclude that the higher the HRC bend of a specimen, the harder the specimen is. . ASSAB steel is a type of alloy steel and thus its composition is much different than that of carbon steel, causing it to give higher hardness compared to carbon steel. 3. From the result obtained, ASSAB steel has an average HRC number of 57. 27 where as carbon steel has an average HRC number of 27. 12. This mean that AASAB steel is harder compared to the high quality carbon steel. c) Brinell Hardness Test 1. For two specimens which carbon steel and mild steel is being tested with brinell hardness test. The BHN values are obtained. The values are depends on the diameter of the indentation ca used. 2.We can conclude that the higher the value of the BHN, the harder the specimen is. 3. From the results, carbon steel has an average BHN of 212 while mild steel only as an average BHN of 99. This confirms that carbon steel is harder than mild steel. 4. Furthermore, the values of BHN obtained might be not accurate because of the limitation that caused human errors. It is difficult for the observer to note the exact diameter of the indentation through the microscope. CONCLUSION In conclusion, from the results we obtained, it is conclude that ASSAB steel is the hardest material, followed by carbon steel and then mild steel.The hardness of the steel is mainly affected by its composition and percentage of carbon. Carbon steel is jailed power is lower than the mild steel. Carbon steel is a breakable material compared to mild steel because of the higher percentage of carbon present in the steel. Thus, relegates almost immediately upon sudden impact. 2. Charpy impact test INTRODUC TION The Charpy Impact Test is the most commonly used test to determine materials resistance to the impact or sudden fracture where a sharp stress raiser is present.Toughness is a pace of the faculty of a material to absorb energy up of fracture. For kinetic (high strain rate) loading conditions and when a nick is present, notch toughness is assessed by using an impact test. Material that experiences very little or no plastic deformation upon fracture is termed brittle whereas material that experiences great deformation upon fracture is termed ductile. The fracture surfaces for brittle material, which has low-energy impact failure, are generally smooth, and in metals eat a crystalline appearance.But for ductile material which has high energy fracture, has regions of shear where the fracture surface is inclined about 45o to the tensile stress, and they have in general a rougher, more highly appearance, called fibrous fracture. THEORY 45? 2 mm 45 mm 10 mm 30? Figure 1 45? 2 mm 45 mm 10 mm 30? Figure 1 In Charpy impact test, the specimen are arrange as shown in the preceding(prenominal) picture and every specimen is prepare will has a notch at the centre of the specimen and the hammer will clout at the region of the notch i. e. stress intentness point.The hammer is release from a specific high which the initial energy having by the hammer is 300J. The scale will show the energy absorbs by each specimen after the experiment and it is recorded. APPARATUS Charpy testing machine SPECIMENS Mild steel and carbon steel PROCEDURE 1. Mild steel and Carbon steel is used in this test. 2. The load was applied as an impact blow from a weighted pendulum hammer that was released from a cocked position at a strict height. 3. The specimen was positioned at the base of the machine. 4.Upon release, a knife-edge mounted on the pendulum strikes and fractures the specimen at the notch, which acts as a point of stress concentration for this high velocity impact blow. 5. After t he weighted pendulum hammer has swung to its master key position, the specimen was removed from the vice and its fracture surface was observed. RESULT specimen Energy Absorbed / J Mild Steel 299 Carbon Steel 30 DISCUSSION 1. In this experiment, we can see that the energy absorbed by mild steel (299J) is higher compared to the energy absorbed by carbon steel (30J).This shows that carbon steel is a more brittle material and mild steel is a more ductile material. 2. correspond to the result which energy absorbed by mild steel is higher and it is more ductile. In addition, carbon steel is a brittle out-of-pocket to presence of the carbon atoms in steel. The presence of these carbon atoms provide resistance for plastic deformation to occur by preventing atoms in the steel to slip and slide over each other. The high percentage of carbon atoms reduces the ability of the steel to absorb energy upon impact. 3.As we observe the experiment that we had done in lab, the carbon steel breaks a lmost immediately when subjected to sudden impact whereas the mild steel shows only deformation and did not fracture. 4. Besides the area where the carbon steel fractures is shinny and smooth which shows that it fractures without much deformation. 5. The diagram below shows fracture surface of the mild steel. 6. The diagram below indicates the fracture surface of the carbon steel. Based on the results, it is clear that the ductility of mild steel is higher than carbon steel.The presence of carbon in carbon steel has minify its ability to absorb energy from the impact. CONCLUSION In conclusion, we can conclude that mild steel has a high level of ductility than carbon steel. Mild steel is tougher than carbon steel. REFERENCE 1. William F. Smith and Javad Hashemi Foundation of Materials light and Engineering McGraw Hill, 2005 2. David D. Rethwish and William D. Callister Fundamentals of Material Science and Engineering, John Wiley & Sons, 2008 3. testing ground worksheet 4. Rollesen Metallurgy For Engineering, ms 15