Lesson 1Microstructure and property relations: ferrite/pearlite, martensite, tempered martensite, bainiteThis part connects steel inner structures—ferrite–pearlite, martensite, tempered martensite, and bainite—to their strength, toughness, and resistance to fatigue. It covers heat treatments, hardness patterns, and how structure changes affect shafts.
Ferrite–pearlite in normalized and hot-rolled barsQuenched martensite and associated brittlenessTempered martensite for strength–toughness balanceBainitic structures and fatigue performanceMicrostructural gradients in large diameter shaftsLesson 2Mechanical behaviour of steels: tensile strength, yield, fatigue limit, toughnessThis part looks at tensile strength, yield strength, stretchiness, and toughness of shaft steels, then links them to fatigue limit and crack growth. It explains stress–strain curves, strain speed, temperature effects, and what that means for design safety margins.
Engineering stress–strain curves and key parametersYield criteria and work hardening in steelsImpact toughness and ductile-to-brittle behaviorFatigue limit, mean stress, and R-ratio effectsTemperature and loading rate influences on behaviorLesson 3Non-ferrous alternatives: bearing bronzes, aluminium alloys, and when to use themThis part compares bearing bronzes and aluminium alloys with steels for shaft jobs. It explains strength, stiffness, resistance to galling, ease of machining, and cost, and shows when non-ferrous choices fix corrosion, weight, or lubrication problems.
Bearing bronzes for bushings and low-speed shaftsAluminum shaft alloys and weight reductionGalling, seizure, and compatibility with bearingsMachinability, cost, and supply considerationsSelection guidelines versus carbon and alloy steelsLesson 4Common shaft materials and grades: AISI 1045, 4140/42CrMo4, stainless options (AISI 304/316)This part reviews common shaft steels and grades, including AISI 1045, 4140/42CrMo4, and stainless 304/316. It compares make-up, hardenability, machinability, weldability, and rust resistance, with tips on typical shaft uses.
Chemical composition of 1045, 4140, 42CrMo4Strength and hardenability differences by gradeMachinability, weldability, and heat-treat response304 vs 316 stainless: corrosion and cost tradeoffsApplication mapping to torque and environmentLesson 5Failure modes and fatigue life estimation methods (S-N curves, Goodman, Miner’s rule)This part explains shaft failure ways and how to estimate fatigue life. It covers high- and low-cycle fatigue, S–N curves, Goodman and Gerber diagrams, Miner’s rule, and handling stress hotspots, surface finish, and changing load sizes.
Typical shaft failure modes and fracture featuresGenerating and interpreting S–N fatigue curvesGoodman and Gerber mean stress correctionsMiner’s rule and cumulative damage assessmentStress concentrations and surface finish factorsLesson 6Surface engineering for shafts: carburising, nitriding, induction hardening, chrome platingThis part reviews surface treatments for shafts, including carburising, nitriding, induction hardening, and chrome plating. It compares hardened layer depth, hardness, leftover stresses, distortion chance, and fit for different load types.
Carburizing cycles, case depth, and distortionGas and plasma nitriding for wear and fatigueInduction hardening of journals and shouldersHard chrome plating and alternative coatingsResidual stresses and grinding burn controlLesson 7Corrosion and wear behaviour in wash-down environmentsThis part looks at corrosion and wear of shaft materials in wash-down spots. It covers water-based chemicals, stainless performance, crevice attack, erosion, and wear from rubbing and corroding, plus design and upkeep plans to make them last longer.
Typical wash-down chemistries and exposure cyclesStainless steel behavior and pitting mechanismsTribocorrosion: combined wear and corrosion effectsSeal design, drainage, and crevice avoidanceCleaning, passivation, and inspection practicesLesson 8Standards and specifications for shafts (dimensional, material, mechanical property limits)This part outlines main shaft standards and specs, covering size tolerances, material grades, strength limits, and checks. It explains how to read standards and note compliance in engineering drawings.
Relevant ISO, DIN, and ANSI shaft standardsMaterial designation and traceability rulesSpecified mechanical property ranges and testsDimensional tolerances and geometric controlsCertification, inspection, and test reportingLesson 9Design allowances and tolerances: keyways, fits, surface finish impact on fatigue lifeThis part covers design extras and tolerances for shafts, including fits, runout, and keyways. It explains how surface finish, rounded edges, and shape tolerances affect stress hotspots, fitting behaviour, and fatigue life.
ISO and ANSI fit classes for shaft–hub jointsKeyway geometry, fillets, and stress raisersRunout, straightness, and balance tolerancesSurface roughness and fatigue strength reductionMeasurement methods and drawing specification
