The Hardness of Metals

by Tabor, D.

• ISBN13: 9780198507765
• ISBN10: 0198507763
• Format: Paperback
• Copyright: 2000-10-05
• Publisher: Oxford University Press

Summary

This book is an attempt to explain hardness measurements of metals in terms of some of their more basic physical properties. It does not deal with the atomic and crystalline mechanism of elastic or plastic deformation, but starting with the elastic and plastic characteristics it shows that the hardness behavior of metals may be expressed in terms of these characteristics. It is hoped that this presentation will provide, for physicists, engineers, and metallurgists, a better understanding of what hardness means and what hardness measurements imply. The book places an emphasis on the physical concepts involved, so that the non-mathematical reader may grasp and appreciate the general physical picture without needing to follow the more detailed treatment.

Table of Contents

Introduction	1	(5)
Scratch hardness	1	(2)
Static indentation hardness	3	(1)
Dynamic hardness	4	(1)
Area of contact	4	(2)
Hardness Measurements By Spherical Indenters	6	(13)
Brinell hardness	6	(2)
Meyer's law	8	(3)
Comparison of Brinell and Meyer hardness	11	(1)
Validity of Meyer's law	12	(2)
Effect of surface roughness	14	(1)
'Shallowing' of the indentation	14	(1)
'Piling-up' and 'sinking-in'	15	(1)
'Strainless' indentation	15	(1)
Ultimate tensile strength and Brinell hardness number	16	(3)
Deformation and Indentation of Ideal Plastic Metals	19	(25)
Stress and strain	19	(2)
True stress-strain curves under tension	21	(3)
True stress-strain curves under tension and compression	24	(2)
Nominal stress-strain curves under tension	26	(2)
Plastic deformation under combined stresses	28	(2)
Conditions for two-dimensional plastic flow	30	(4)
Deformation of an 'ideal' plastic metal by a flat punch	34	(3)
Effect of friction	37	(3)
Deformation by a flat circular punch	40	(4)
Deformation of Metals By Spherical Indenters. Ideal Plastic Metals	44	(23)
Onset of plastic deformation	46	(1)
Complete or full plastic deformation	47	(2)
Pressure-load characteristic	49	(2)
Range of validity of Meyer's law	51	(3)
Deformation of the indenter	54	(1)
Brinell hardness measurement of very hard metals	55	(6)
Effect of surface roughness	61	(3)
'Piling-up' and 'sinking-in'	64	(1)
'Strainless' indentation	65	(2)
Deformation of Metals By Spherical Indenters. Metals Which Work-Harden	67	(17)
Yield pressure as a function of the size of the indentation	67	(2)
Co-ordination of results	69	(1)
Yield pressure as a function of the stress-strain characteristic	69	(5)
Yield pressure and stress-strain curves for deformed metals	74	(2)
Derivation of Meyer's laws	76	(2)
The Meyer index and the stress-strain index	78	(1)
Brinell hardness and ultimate tensile strength	79	(5)
Deformation of Metals By Spherical Indenters. 'Shallowing' and Elastic 'Recovery'	84	(11)
Cyclic deformation of 'recovered' indentations	84	(1)
'Shallowing' and elastic 'recovery'	85	(3)
Distribution of stresses	88	(2)
Released elastic stresses and the adhesion of metals	90	(3)
Processes involved in the Brinell test	93	(2)
Hardness Measurements With Conical and Pyramidal Indenters	95	(20)
Conical indenters	95	(2)
Pyramidal indenters	97	(3)
Knoop indenter	100	(1)
Indentation of an ideal plastic metal by a wedge-shaped indenter	101	(2)
Indentation by conical and pyramidal indenters	103	(2)
Indentation of metals which work-harden	105	(1)
Pin-cushion and barrel-shaped indentations	106	(1)
Vickers hardness number and ultimate tensile strength	107	(1)
Rockwell and Monotron hardness	107	(5)
The meaning of hardness: the Vickers and Brinell test	112	(3)
Dynamic or Rebound Hardness	115	(26)
Indentation produced by impact	115	(1)
Four main stages of impact	116	(1)
Mean dynamic yield pressure P	117	(3)
Effect of variation in the value of P	120	(1)
Validity of equations (6) and (10)	121	(4)
Shore rebound scleroscope	125	(1)
Condition for elastic collisions	126	(3)
Coefficient of restitution	129	(1)
Time of impact: elastic collisions	130	(2)
Time of impact: plastic collisions	132	(1)
Electrical measurement of the time of impact	133	(4)
Comparison of static and dynamic hardness	137	(1)
Meaning of dynamic hardness	138	(3)
Area of Contact Between Solids	141	(32)
Asperities of hemispherical shape	141	(2)
Asperities of conical and pyramidal shape	143	(2)
Area of real contact	145	(1)
Area of real and apparent contact	146	(1)
Effect of reducing the load	147	(1)
Measurement of the area of contact	148	(2)
Contact of flat surfaces	150	(5)
Appendix
I. Brinell hardness	155	(3)
II. Meyer hardness	158	(2)
III. Vickers hardness	160	(4)
IV. Hardness conversion	164	(2)
V. Hardness and ultimate tensile strength	166	(1)
VI. Some typical hardness values	167	(5)
Index
Name	172	(1)
Subject	173