Statistical Analysis of Structural Plate Mechanical Properties (Part 1)

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2.1.2 THE 2-MILL GROUP Due to the fact that the data from Mills 2 and 6 (we will refer to these mills as the “2-mill group”) were in the form of mill test reports that were not compatible with the data from the other mills (i.e., the 4-mill group) and also did not include CVN test results, the statistical analyses of the 4-mill group and the 2-mill group were conducted separately. Most plates from the 2-mill group included only one test location per plate, while all plates from the 4-mill group included seven test locations per plate. In other words, the survey data provided by the 4-mill group could be used in a study of variability within a plate as well as between plates, but the mill test data provided by the 2-mill group could be used only in a study of the variability between plates. Mills 2 and 6 (the 2-mill group) submitted acceptable data from 1280 heats while the Mills 1, 3, 4, and 5 (the 4-mill group) submitted data from 46 heats only. This large discrepancy in the number of data in the two groups would bias the results towards Mills 2 and 6, further justifying the need for separate statistical analyses of the two groups. 2.2 DATA PREPARATION Before the statistical analysis process could be conducted, all the data had to be prepared and carefully organized to facilitate the analysis. The data preparation process began with the rearranging and organizing of the data from all the mills into groups. The initial sorting criteria were producer and ASTM specification. The next criterion was plate thickness, t, where the plates were grouped according to the following thickness ranges defined: 6
Group T1 Group T2 Group T3 Group T4 t 0.75 in. 0.75 in. < t 1.5 in. 1.5 in. < t 2.5 in. 2.5 in. < t 4.0 in. The description of the organized data from the 4-mill group (Mills 1, 3, 4, and 5) is summarized in Table 2.1. Table 2.1: Data Description for the 4-Mill Group (Mills 1, 3, 4, and 5). Mill 1 3 4 5 Casting Method Ingot and Strand Cast Strand Cast Strand Cast Ingot and Strand Cast Method of Production BOF N/A BOF BOF(5), EAF(13) No. of Heats 10 10 10 15 No. of Plates 20 19 16 18 ASTM Specification A572 A588 A572 A588 A572 A588 A572 A588 Type 2 Grade B Type 2 Grade A Type 2 Type 3 Grade B Type 2 Grade A/B T1 6(3) 6(3) 2(1) 2(1) 4(2) 0 4(2) 2(2) 3(2) No. of Plates(Heats) in T2 2(1) 2(1) 3(2) 4(2) 0 4(3) 4(3) 2(2) 3(2) Each Group T3 2(1) 2(1) 4(2) 2(1) 0 0 0 2(2) 3(2) T4 0 0 0 2(1) 0 0 0 2(2) 1(1) No. of Data for Tensile Test 140 133 112 126 0 F 420 399 336 378 No. of Data for CVN Test 40 F 420 399 336 378 70 F 420 399 336 378 The distribution of plates among the four mills is presented graphically in Figure 2.2. Figure 2.2: Distribution of Plates for the 4-Mill Group (Mills 1, 3, 4 and 5). Distribution of Plates Number of Plates 16 14 12 10 8 6 Mill 5 Mill 4 Mill 3 Mill 1 4 2 0 A 572-T1 A 572-T2 A 572-T3 A 572-T4 A 588-T1 A 588-T2 A 588-T3 A 588-T4 Group 7
Page 2 and 3: STATISTICAL ANALYSIS OF STRUCTURAL
Page 4 and 5: FORWARD This work was sponsored by
Page 6 and 7: TABLE OF CONTENTS Chapter Page CHAP
Page 8 and 9: CHAPTER 1 INTRODUCTION 1.1 INTRODUC
Page 10 and 11: CHAPTER 2 DATA DESCRIPTION AND PREP
Page 14 and 15: It can be observed from Figure 2.2
Page 16 and 17: 2.3 PROPERTIES TO BE STUDIED In the
Page 18 and 19: understand the significance of the
Page 20 and 21: 3.1.1 ORGANIZED DATA FROM THE 4-MIL
Page 22 and 23: Table 3.4: Raw Data on Carbon Equiv
Page 24 and 25: carbon equivalent values measured w
Page 26 and 27: CE vs. Tensile Strength 95 90 85 A5
Page 28 and 29: 100 95 90 A572: y = 52.667x + 57.62

Statistical Analysis of Structural Plate Mechanical Properties (Part 1)

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