LECTURE 11.2LECTURE 11.2

LECTURE OUTLINELECTURE OUTLINE

Weekly ReadingWeekly ReadingLesson 11 Prototype ExamLesson 11 Prototype ExamThe Processing of SteelThe Processing of Steel

CHAPTER 36: AN CHAPTER 36: AN INTRODUCTION TO INTRODUCTION TO

PERFORMANCE INDICES PERFORMANCE INDICES "The Proof of the Pudding Is in the

Eating"

The use and/or usefulness of a material for a particular application depends critically on its properties, which in turn are dependent on structure, itself a function of the processing parameters. When a material is being considered for a particular application, an entire suite of properties must be evaluated. This list of properties will invariably include the ease of fabrication and the cost; often cost may be the overriding factor. The present chapter introduces the ideas of a performance index—a quantitative measure of the fitness of a given material for a particular application. This chapter starts with a tongue-in-cheek example of the selection of a material for ancient body armor. However, the example permits a material selection to be made from a narrow list of choices and on the basis of a few selected material properties. The second example is somewhat more complex: the choice of material(s) for weight-limited design—aircraft fuselage and wings. The discussion begins by presenting the property data for various candidate materials in the form of a histogram, and then shows how two or more sets of property data may be displayed on a graph or map. Finally, the reader is introduced to the concept of Ashby maps, which are used to present and analyze data on all possible material types: metals, ceramics, polymers, and composites.

THE PROCESSING OF STEELTHE PROCESSING OF STEEL

The Raw MaterialsThe Raw MaterialsFire SettingFire SettingThe Blast FurnaceThe Blast FurnaceThe “Converter”/Basic Oxygen Furnace The “Converter”/Basic Oxygen Furnace

(BOF)(BOF)Continuous CastingContinuous CastingHot-RollingHot-RollingCold-RollingCold-Rolling

STEEL PROCESSING FLOW STEEL PROCESSING FLOW CHART ICHART I

RAW MATERIALSRAW MATERIALS

Raw Material

Source

Iron-ore (Taconite)

Minnesota

Coal West Virginia. Coked at 1300˚C (2400˚F) for 1 day.

Limestone Kentucky

Scrap South America

FIRE SETTING: CIRCA FIRE SETTING: CIRCA A.D.A.D. 1550 1550

THERMAL SHOCKTHERMAL SHOCK

TACONITETACONITE

PRODUCTION OF COKEPRODUCTION OF COKE

STEEL PROCESSING FLOW STEEL PROCESSING FLOW CHART IICHART II

MagneticSeparation

GravitySeparation

THE BLAST FURNACETHE BLAST FURNACE

CHEMICAL REACTIONS IN CHEMICAL REACTIONS IN THE BLAST FURNACETHE BLAST FURNACE

STEEL PROCESSING FLOW STEEL PROCESSING FLOW CHART IIICHART III

THE BASIC OXYGEN THE BASIC OXYGEN FURNACE (BOF)FURNACE (BOF)

““REFRACTORIES”REFRACTORIES”

SOME APPROXIMATE SOME APPROXIMATE TEMPERATURESTEMPERATURES

CONTINUOUS CASTING ICONTINUOUS CASTING I

CONTINUOUS CASTING IICONTINUOUS CASTING II

A “FOUR-HIGH” ROLLING A “FOUR-HIGH” ROLLING MILLMILL

HOT-ROLLING MILLHOT-ROLLING MILL

HOT-ROLLINGHOT-ROLLING

RECRYSTALLIZATIONRECRYSTALLIZATION

COLD-ROLLING: STRIP COLD-ROLLING: STRIP THICKNESS AND VELOCITYTHICKNESS AND VELOCITY

a

Pay-Off Coil Take-UpCoilStand1Stand2Stand3Stand4Stand55.7mph9.114.623.53861mph2.25mm1.450.90.560.340.21mm