Lab Report 1

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School

Georgia Institute Of Technology *

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3020

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Mechanical Engineering

Date

Apr 3, 2024

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pdf

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Laboratory 1: Metals CEE 3020 Civil Engineering Materials Submitted to: Alexandra Wu by: Sachin Dasu Section B6 Group 1 Thomas Reid Cabe III Katerina Efthymiou Maggie Jiang Shruti Sarkar Sarah Elizabeth Scioli Abstract 10% Introduction 10% Experiment 5% Results 25% Discussion 25% Conclusion 10% Technical Writing 10% Graphics: Design 5% TOTAL Due Date: September 15, 2023

Abstract The main objectives of the first experiment, the Tension Test of Steel and Aluminum, is to develop an understanding of elastic and inelastic behavior of steel and aluminum and the relative influence of composition and processing on these behaviors, measure the strength and certain elastic and inelastic properties of steel and aluminum alloys, observe the behavior of metals under axial tensile load, and to study the failure characteristics of metals under uniaxial tensile load. The main objectives of the second experiment, the Impact Test of Steel and Aluminum, is to develop and understanding of impact toughness testing, measure impact toughness for both brittle and ductile metal alloys, characterize the fracture surface in both brittle and ductile failures, distinguish between ductile and brittle fracture, comparing both the impact toughness and fracture surfaces of different alloys and the behavior of a single alloy but at different temperature, and to assess the influence of col-working on fracture behavior during impact loading. This laboratory is broken up into four parts: Tension Test of Steel and Aluminum, Microscopy, Hardness Testing, and Impact Test of Steel and Aluminum. These are achieved through a tension test, microscopic examination, hardness test, and impact test. The samples are tested through an extensometer, analyzed under a microscope, a hardness testing machine, and a Charpy impact test. The samples analyzed in this experiment are two aluminum allows, Al-6061 and Al-2024, and a steel sample. The results obtained in this laboratory are analyzed and detailed below in this report.

Table of Contents Introduction ...................................................................................................................................... 1 Experiment ....................................................................................................................................... 1 Materials ................................................................................................................................... 1 Equipment ................................................................................................................................ 1 Procedure .................................................................................................................................. 1 Results .............................................................................................................................................. 2 Discussion ........................................................................................................................................ 8 Conclusion ...................................................................................................................................... 10 References ...................................................................................................................................... 11 Appendices ..................................................................................................................................... 12

1 Introduction The Metals Laboratory is comprised of four different sections- the Tension Test of Steel and Aluminum, Microscopy, Hardness Testing, and the Impact Test of Steel and Aluminum. The purpose of this laboratory is to develop an understanding of different material samples under different loads to determine their compositions and characteristics. The objective of this laboratory is to determine the behavior of the metal samples under load and understand their failure characteristics. Experiment Materials The materials and specimens used in the Tension Test of Steel and Aluminum are described as the following from the laboratory handout. “ASTM E8 standard flat tensile specimens of steel and aluminum alloy will be used. ‘Typical’ values for these specimens c an be found on matweb.com. If typical values cannot be found for these exact samples, use a specimen that is comparable to the one tested, listing the name of this alternate specimen. The materials used in the lab are as follows: Steel Specimen Hot Rolled (HR) Steel – (AISI 1008) Aluminum Specimens Aluminum – (Al 2024 – T4) Aluminum – (Al 6061 – T6) ”. The materials and specimens used in the Impact Test of Steel and Aluminum are described as the following from the laboratory handout. “Standard notched impact samples (2 metals will be tested; specifications to be provided in lab). Each lab section should have 6 samples, 3 from each of 2 alloys, to be tested at 3 temperatures. The alloys are as follows: Specimens Hot Rolled Steel A36, notched impact sample Aluminum 6061 – 76, notched impact sample ”. Equipment The equipment utilized in the tension test of steel and aluminum are listed below. • A universal testing machine with grips (Precision +/- 1 lb) • Extensometer (Precision +/- 5 µσ) • Digital Caliper (Precision +/- 0.0005 inch) • Metal Scale • Tape • Safety Glasses • Pencil. For Part 2 of this laboratory, Microscopy, a microscope was utilized to review the samples. For Part 3, the Hardness Test, a hardness testing machine was used. Part 4, the Impact Test of Steel and Aluminum, the materials used are listed below. • Charpy impact tester • Oven • Dry ice • Tongs, for handling samples • Infrared thermometer Procedure

2 The procedures that were followed in this laboratory are detailed in the laboratory handout, which is attached in the References section of this laboratory report. There were no deviations from the procedures that were followed. Results Part 1. Tension Test 1. The definitions for the following terms are found from Professor Dai Sheng’s lecture slides, which will be attached in the References section. i. Engineering stress Load per cross-sectional area. ii. Engineering Strain Change in deformation length over original length. iii. True Stress Load per instantaneous area. iv. True Strain Natural log of the addition of 1 and the true stress. v. Proportional Limit Maximum load that a material can sustain without any deformation taking place. vi. Yield Strength Amount of stress where a specific amount of deformation takes place. vii. Upper Yield Point Maximum load necessary for deformation to take place. viii. Lower Yield Point Minimum load necessary for deformation to take place. ix. Modulus of Elasticity Ratio of stress to strain x. 0.2% Offset Yield Strength Amount of stress required to result in a strain of 0.2%. xi. Ultimate Tensile Strength Maximum load that can be applied before failure. xii. Rupture Strength Maximum stress that can be sustained without fracturing. xiii. Ductility Measure of a material’s ability to undergo significant plastic deformation before rupture or breaking. xiv. Toughness Ability of a material to absorb energy and plastically deform until fracturing (or ability to withstand impact loading). 2. The two engineering stress-strain diagrams for each material show the entire stress-strain curve and a ‘close - up’ of the early stress -strain behavior which captures the elastic behavior, yield points, and 0.2% offset yield stress. Figure 1 shows the entire stress-strain curve for hot rolled steel (AISI 1008). Figure 1. Stress-Strain Diagram for AISI 1008.

3 Figure 2 shows the close-up of the early stress-strain behavior of AISI 1008. Figure 2. Close-up of early stress-strain behavior of AISI 1008. Figure 3 shows the entire stress-strain curve for Al-2024. Figure 3. Stress-Strain Diagram of Al-2024. 0 10000 20000 30000 40000 50000 60000 70000 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 Strain (Psi) Strain (in/in) Stress-Strain of AISI 1008 -10000 0 10000 20000 30000 40000 50000 60000 -0.02 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 Stress (Psi) Strain (in/in) Stress-Strain Diagram of AL-6061

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