67065 - Metallurgy with Laboratory

Learning outcomes

To understand the metallurgical principles governing any particular process starting from the aspects of plastic deformation, the variability in mechanical properties, the operating behaviors up to the fracture mechanisms at high and low temperature in alloy steels and non ferrous metals

Course contents

DEFORMATION MECHANISMS IN METAL

Elastic and plastic behavior, deformation of single crystals

Deformation by slip, slip in perfect lattice and slip by dislocations movement;

Critical resolved shear stress for slip;

Deformation by twinning;

Dislocations in FCC, in BCC and Hexagonal close packed Lattice;

Stacking faults, deformation bands and Strain Hardenings of single crystals;

Forces between dislocations, dislocation climb, interaction of dislocations and Jogs;

Dislocations sources, moltiplications of dislocations, dislocations Pile-up;

Dislocation reactions and sessile dislocations;

Interactions with point defects;

Deformation of polycrystalls;

Bauschingher effect;

Internal friction in metals and mechanisms;

STRENGTHENING MECHANISMS

Introduction

Strengthening from grain boundaries;

Yield-Point Phenomenon;

Strain Aging;

Solid solution strengthening;

Deformation of Two–Phase Aggregates;

Strengthening from fine particles;

Strengthening Due to Point Defects;

Martensite Strengthening;

Cold worked structure;

Strain hardening;

Annealing of cold worked metal;

Preffered orientation (texture);

RECRYSTALLIZATION

Related annealing phenomena

Deformation rate and crystallization temperature

FRACTURE

Fracture mechanisms: Cleavage, Ductile fracture

Environment assisted fracture

Intergranular fracture

Fatigue fracture

Crack growth criteria: Griffth, Irwin-Orwan

Relation between energy release rate and stress intensity factor (KIc)

FATIGUE

Definitions and date presentation

Effect of mean stress

Effect of material variables

Fatigue mechanisms

Thermal fatigue

Fatigue crack propagation

Corrosion fatigue and stress corrosion cracking

Life prediction

Limitis to fatigue failures

CREEP AND STRESS RUPTURE

The high-temperature materials problem

Time dependent mechanical behavior

The creep curve

Mechanisms of creep deformation

Fracture at elevated temperature

Alloys for High-Temperatures

APPLICATIONS TO MATERIALS TESTING

The tension test, true strain curve

The hardness test

Stress intensity factor

Toughness testing-toughness of materials

Notched-bar impact tests, charpy test

Significance of transition-temperature curve

Metallurgical factors affecting transition-temperature

Temper embrittlement

ALLOY STEELS DESIGNATION

Low alloy constructional steels by general use

Constructional special alloy steels

Alloy tool steels

Stainless steels

Heat-resisting steels and low temperature resisting steels

CAST IRONS

Structure and properties of cast irons

NON_FERROUS METALS AND ALLOYS

COPPER and its alloys

Bronzes and Brasses

ALUMINIUM and its alloys

Wrougth aluminium alloys

Cast aluminium alloys

TITANIUM and its alloys

MAGNESIUM and its alloys

Laboratory program:

Recrystallization.: deformation rate and recrystallization temperature (DTA) with optical microscope observations;

Construction of fracture mechanisms by scanning electron microscope;

Analyses with EDS (Energy dispersive spectroscopy) in metals, alloys composites and ceramics;

Surface modification of steels: Diffusion mechanisms; Carburizing, properties and structure, microhardness misures profile;

Temper embrittlement;

TGA and DTA on aluminium alloys

Construction of spectra by charpy tests- resilience of alloy steels

Tribology and its significance: friction and wear-pin on disk;

Elastic modulus significance: misures on metals, alloys, composites and ceramic materials

Metallographic observations on Stainless Steels: Corrosion forms by sensitizing range

Dilatometric measures on metal and ceramics

Readings/Bibliography

Metallurgia (Paulucci) Vol. 1-2-3

Metallurgia (Cigada -G.Re) vol. 2

Metallurgia (D. Sinigalia ) vol 1

Teaching methods

lessons in class and set of university lectures

laboratory exercise with optical and electronic microscope, indenter for hardness measures, DSC and elastic modulus instrument

Assessment methods

The final exam, oral type, relating to contents of 8 CFU, is an assessment of the achievement of learning objectives:

-know the extractive metallurgy and problems relating to principal alloys, ferrous and non;

-know the exercise behavior of the major alloys and related iusses;

-criteria for the choise of laboratory techniques for the investigation of metallurgical problems.

Teaching tools

Blackboard, videoprojector, PC

Office hours

See the website of Angelo Casagrande