METALLOGRAPHY AND FAILURE ANALYSIS
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- Versione italiana
- Academic year
- 2017/2018
- Teacher
- MATTIA MERLIN
- Credits
- 6
- Didactic period
- Primo Semestre
- SSD
- ING-IND/21
Training objectives
- Aim of the course is to initiate the students to the metallographic practice and to provide methods to understand the most important microstructures of ferrous alloys and light alloys, according to production processes, heat treatments and supply conditions. The student will learn the potentiality of some advanced techniques for the characterization of metallic materials. Fundamentals of both non-destructive and destructive testing will be presented. The students will also learn to understand the micro and macro mechanisms involved in static, dynamic and fatigue failures.
Moreover, the methodological approach to the Failure Analysis as well as to the laboratory routine analysis will be presented.
The knowledge of these aspects is very important in the working life of a mechanical engineer in both cases of the management of a metallurgical laboratory and the maintenance of industrial plants. Prerequisites
- The student must have the knowledge of the most important characteristics of both ferrous and non-ferrous alloys.
Course programme
- The programme of the course is divided in two parts:
1) Frontal lectures on the following topics:
- Techniques for metallographic analysis: visual inspection, optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM). Microanalytical techniques (EDS and WDS). Quantitative chemical analysis (OES) in brief. Non-contact 3D optical profilometry. Procedures for metallographic specimen preparation. (10 hours)
- Quantitative metallographic techniques for measuring the grain size and to evaluate the non-metallic inclusions. (7,5 hours)
- Hardness tests and impact strength tests: theoretical aspects. (5 hours)
- Replica techniques in metallography and non-destructive testing (NDT): theoretical aspects. (2,5 hours)
- Diagnosis of metallurgical defects. Focus on defects in aluminium alloys high pressure diecastings. (2,5 hours).
- Description and identification of the most important micro and macro mechanisms of fracture: theoretical aspects. (2,5 hours)
- Microstructural aspects of fatigue. (2,5 hours)
- Failure Analysis techniques: methodological approach, case histories. (7,5 hours)
2) Laboratory experiences on the following topics (20 hours):
- Metallographic practice: specimen preparation and specific critical issues. Bright field and dark field inspections, differential interference contrast and polarised light observations. Interpretation of microstructure and analysis of some of the most important alloys available for mechanical applications (plain carbon steels, low and high alloy steels, stainless steels, cast irons, aluminium alloys).
- Microstructural analysis of bulk and surface hardening treatments: hardness and microhardness testing.
- Fracture surface analysis of tensile, impact strength and fatigue samples: fractography by means of scanning electron microscopy (SEM) and EDS microanalysis.
- Surface analysis by means of non-contact 3D optical profilometry: data acquisition and interpretation of the results.
- Application of image analysis techniques in ferrous and/or non-ferrous alloys.
- Instrumented impact strength tests and interpretation of the results.
- Replication of metallic surfaces and non-destructive testing (ultrasonic testing, liquid penetrant testing).
The normative aspects (UNI, EN, ISO and ASTM) are considered as a reference during the course. Didactic methods
- The course is organized as follow:
- frontal lectures on all the course’s topics;
- laboratory lessons concerning practical aspects of the course’s topics. Learning assessment procedures
- The examination is oral and divided in 2 sections.
The first section is performed in order to assess the understanding of the theoretical subjects tackled during the frontal lectures. In particular, the ability of critically linking the different subjects covered during the course, rather than the capacity to simply repeat the specific topics, are evaluated.
In the second section the student has to demonstrate the understanding of the fundamental skills for the metallographic preparation and for the interpretation of the microstructure of studied metallic materials, in relation to production processes and heat treatments. Moreover, the ability to tackle failure analysis problems with an appropriate methodological approach will be evaluated.
The student must show a sufficient knowledge of the topics in both sections of the examination. Reference texts
- - Lesson notes and teacher’s handouts.
Textbooks for further study:
- B.L. Bramfitt e A.O. Benscoter, Metallographer’s guide – Practices and procedures for irons and steels, ASM International.
- E. Totten et al., Failure analysis of heat treated steel components, ASM International.
- V. Ramachandran, Failure analysis of engineering structures: methodology and case histories, ASM International.
- Collana tecnica AQM, I criteri di scelta e trattamento degli acciai da costruzione e da utensili.
- Le Prove non Distruttive, Vol.1, Ed. AIM.
- Handbook of defects in high pressure diecastings, Ed. AIM.
