IE 312 Joining Module Lab Recitation FA22

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Pennsylvania State University *

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312

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Mechanical Engineering

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Dec 6, 2023

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Joining Module – 2 hr Recitation With Data for Lab Reports In Recitation: -quiz on Machining Module 2/2 -welding and joining fundamentals -discussion of welding data and lab reports (Week 1/2 and Week 2/2) Welding Lab Data and Report (Week 1/2): Weld Property Analysis Investigate the effect of heat from a welding arc on the hardness (strength) in the fusion zone (FZ or weld metal) and the heat-affected zone (HAZ) of steel and aluminum welds. The resultant hardness and strength across the weld depend on the chemistry and microstructure of the material being welded. When selecting materials for welded construction, it is the welded properties in fusion zone and the HAZ rather than the properties of the base metal that typically limit performance. Cross Section Through a Steel Weld (polished and etched) to reveal the BM, HAZ and FZ 1

Full penetration butt welds in various materials have been performed, similar to the weld shown. The load to failure of the base material before welding and the tensile strength of the final welded joint has been measured. In addition, hardness measurements have been made across the weld region from the fusion zone (FZ), through the heat-affected zone (HAZ), and into the base metal (BM). Base Metals AISI 1018 steel – HR condition AISI 4340 steel – Q&T condition 1100-H14 aluminum 6061-T6 aluminum Welds Performed Base Metal Filler Metal Welding Process Used 1018 steel E6013 SMAW 4340 steel E7018 SMAW 1100-H14 aluminum 1100 and 4043 aluminum GTAW 6061-T6 aluminum 1100 and 4043 aluminum GTAW Data Steel Welds sample thickness = 0.125 in. sample width = 1.0 in. SMAW conditions: 180 amps, AC, electrode dia. = 0.125 in., no weld pre-heat Base metal 1018 steel 4330 steel Electrode type E6013 E10018 Initial base metal hardness (HV) 160 423 Base material TS before welding 60,000 psi 180,000 psi Hardness after welding (HV) fusion zone 2 mm from the weld 4 mm in from the weld 6 mm from the weld 10 mm from the weld 20 mm from the weld 170 HV 157 HV 158 HV 159 HV 160 HV 160 HV 380 HV 560 HV 530 HV 520 HV 415 HV 423 HV Location of fracture HAZ HAZ Welded fracture load 7,500 lbs 15,000 lbs Fracture type ductile failure brittle cracking 2

Aluminum Welds sample thickness = 0.125 in. sample width = 1.0 in. GTAW conditions: 110amps, AC, argon flow rate = 25 ft 3 /hr Base metal (BM) 1100-H14 6061-T6 Filler wire type 1100 4043 1100 4043 Initial BM hardness (HRF) 92 98 Base material TS before welding 15,020 psi 24,050 psi Hardness after welding (HRF) Hardness after welding (HRF) fusion zone 2mm from the weld 4 mm in from the weld 6 mm from the weld 10 mm from the weld 20 mm from the weld 84 82 84 86 91 92 99 82 84 86 91 92 84 88 90 92 96 98 99 88 90 92 96 98 Location of final fracture HAZ HAZ FZ HAZ Welded fracture load (lbs) 1,200 lbs 1,200 lbs 1,775 lbs 2,270 lbs Fundamental concepts that you need to understand to correctly analyze the Part A data -What happens to the microstructure and properties of a cold worked material (Ex: 1100-H14) when it is heated above its recrystallization temperature? -What happens to the microstructure and properties of a precipitation hardened material (Ex: 6061-T6 aluminum) when it is heated above its solution temperature or above its peak aging temperature? -What happens to the microstructure and properties in the HAZ of a steel in with good weldability (Ex: 1018 HR steel) when it is cooled rapidly during a typical weld cooling cycle? -What happens to the microstructure and properties of a steel in the HAZ with poor weldability (Ex: 4330 Q&T steel) when it is cooled rapidly during a typical weld cooling cycle? Report (2 pages text, single-spaced + figures and tables) Comment on the relative strength (hardness) observed in the fusion zone (FZ) and the heat-affected zone (HAZ) for all of the weld data shown. For each material describe the specific microstructure change that happens in the HAZ that is at the root cause of the HAZ hardness changes observed. Describe welding technique changes that could be used to improve the overall strength (if possible) for each base metal/filler metal combination. 3

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Welding Lab Data and Report (Week 2/2): Weld Process Control Control of arc welding variables is key to producing high quality welds of proper size and shape. In this task, we will investigate the effects of flux-cored arc welding (FCAW) variable for making ‘bead-on-plate ” welds on AISI 1020 steel. An automatic torch travel welding device to allow us to control the variables that we want to analyze by removing human variability from manual FCAW. The device is set up with Flux-Core wire that is also aided by inert gas (75% Argon and 25% Carbon Dioxide). A total of 16 weld were made using the following welding conditions: 4

For each welding condition the welding heat input (kJ/in) can be calculated Each weld was cross sectioned, ground, polished and etched to reveal the cross-sectional geometry of the weld beads. This includes the overall height and width of the weld bead as well as the depth of penetration into the metal and the amount of reinforcement above the surface of the welded plate. 5

Data The resultant weld geometry data for each weld is indicated here. Units are in inches. Weld Images 6

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Report (2 pages text, single-spaced + figures and tables) The FCAW welding guide posted on CANVAS is a useful guide for understanding the influence of welding conditions on weld bead geometry. Refer to it for assistance in completing your report. What is the influence of individual welding variables and heat input (a combined variable) on the various aspects of weld bead geometry. (Data plots and statistical analysis are needed.) Which variables have the most dominant effects on the various aspects of weld bead geometry? Do the results of your experiment agree with the literature? Discuss. Problem solving: Write a 2-paragraph description that would be part of a training guide for new welders that describes what FCAW welders should do to maintain adequate weld penetration during manual welding. Make sure that you include discussion of other significant welding variables that may have been held constant in the lab data that you analyzed. 7