tailieunhanh - Standard Handbook of Machine Design P11

CHAPTER 8 THE STRENGTH OF COLD-WORKED AND HEAT-TREATED STEELS Charles R. Mischke, ., RE. Professor Emeritus of Mechanical Engineering Iowa State University Ames, Iowa INTRODUCTION / STRENGTH OF PLASTICALLY DEFORMED MATERIALS / ESTIMATING ULTIMATE STRENGTH AFTER PLASTIC STRAINS / ESTIMATING YIELD STRENGTH AFTER PLASTIC STRAINS / ESTIMATING ULTIMATE STRENGTH OF HEAT-TREATED PLAIN CARBON STEELS / ESTIMATING ULTIMATE STRENGTH OF HEAT-TREATED LOW-ALLOY STEELS / TEMPERING TIME AND TEMPERATURE TRADEOFF RELATION / COMPUTER PROGRAMS / REFERENCES / RECOMMENDED READING / GLOSSARY AR A B d D DI DH EJD. | __CHAPTER 8_ THE STRENGTH OF COLD-WORKED AND HEAT-TREATED STEELS Charles R. Mischke . . Professor Emeritus of Mechanical Engineering Iowa State University Ames Iowa INTRODUCTION STRENGTH OF PLASTICALLY DEFORMED MATERIALS ESTIMATING ULTIMATE STRENGTH AFTER PLASTIC STRAINS I ESTIMATING YIELD STRENGTH AFTER PLASTIC STRAINS ESTIMATING ULTIMATE STRENGTH OF HEAT-TREATED PLAIN CARBON STEELS ESTIMATING ULTIMATE STRENGTH OF HEAT-TREATED LOW-ALLOY STEELS TEMPERING TIME AND TEMPERATURE TRADEOFF RELATION COMPUTER PROGRAMS REFERENCES RECOMMENDED READING GLOSSARY AR A B Fractional area reduction Area Critical hardness for carbon content and tempering temperature Rockwell C scale d D D DH EJD f F H IH Diameter Tempering decrement Rockwell C scale carbon ideal diameter in Ideal critical diameter in Distant hardness Rockwell C scale Equivalent Jominy distance sixteenths of inch Tempering factor for carbon content and tempering temperature Load temperature degrees Fahrenheit Quench severity in 1 Initial hardness Rockwell C scale STANDARD HANDBOOK OF MACHINE DESIGN m Strain-strengthening exponent n Design factor r Rq rt S e S t Radius Maximum hardness attainable Rockwell C scale As-quenched Jominy test hardness Rockwell C scale Tempered hardness Rockwell C scale Engineering endurance limit Engineering ultimate strength in tension Engineering yield strength percent offset Time e True strain T1 Go 7 ZA Factor of safety Strain-strengthening coefficient Normal stress Sum of alloy increments Rockwell C scale To T Octahedral shear stress Shearing stress Subscripts a B Axial Long traverse c C D Compression Circumferential Short traverse e f L R Endurance Fracture Longitudinal Radial s t Shear Tension u Ultimate y 0 Yield No prior strain INTRODUCTION The mechanical designer needs to know the yield strength of a material so that a suitable margin against permanent distortion can be