INSIDE THE MICROSTRUCTURE OF STRUCTURAL BOLTS FORMED THROUGH THREAD AND PROFILE ROLLING: Refining the internal structure of structural bolts for more ... (Advanced Mechanical Engineering Components)

By Rickbed Nandi

This book is addressed to advanced students and to scholars who already possess the vocabulary of mechanical metallurgy and structural engineering, and who are prepared to follow an argument that crosses freely between them. It is not an introduction to fasteners. It assumes that the reader knows what a dislocation is, can read a continuous-cooling diagram without assistance, and understands why a limit-state format separates resistance from load effect. What it does not assume is that the reader has ever been asked to hold these things together in a single account of one component. That is the task attempted here: to follow a structural bolt from the wire rod through the rolling die into the joint, and to show that the reliability of a slip-critical connection is decided at length scales eight orders of magnitude below the scale at which the connection is designed.
The organising claim of the book can be stated in one sentence. Thread rolling is not a manufacturing convenience that happens to produce an adequate thread; it is a severe plastic deformation process that constructs a graded microstructure and a graded residual stress field at the thread root, and the properties of that graded region - not the bulk properties recorded on the mill certificate - govern the fatigue and environmental performance of the fastener. Everything in the following forty-two chapters is either an elaboration of that claim, a quantification of it, or an examination of the circumstances in which it fails.
The reader should be warned at the outset that the book takes a position on several matters that remain contested. It argues that martensite block width, not prior austenite grain size, is the operative Hall-Petch length in these steels, while acknowledging the minority view. It argues that the routine practice of quoting a single number for the residual stress at a rolled thread root is meaningless without the measurement method, sampling depth and gauge volume attached to it, and it shows why X-ray and neutron determinations of the same bolt differ by a factor of four without either being wrong. Most consequentially, it argues that the celebrated fatigue advantage of rolling after heat treatment is largely a low-preload phenomenon, and that at the preloads actually used in slip-critical joints a substantial part of that advantage has already been consumed. This is not a comfortable conclusion, and it is not the conclusion that the standard textbook accounts encourage.
A second warning concerns the treatment of hydrogen. The same rolled root layer that delivers the fatigue benefit is the layer most vulnerable to hydrogen-assisted cracking, because it is the hardest, the most heavily dislocated, and the one lying immediately beneath a tensile subsurface field once the compressive skin is stripped by electropolishing or consumed by preload. The book therefore treats the rolled thread as a conditional benefit rather than an unconditional one, and it devotes considerable space to the circumstances - cathodic protection, hot-dip galvanising after acid pickling, immersion, high sustained preload - under which the condition fails. The San Francisco-Oakland Bay Bridge anchor rods are examined at length not as a curiosity but as the clearest available demonstration that three individually compliant decisions can combine into a failure within days of tensioning.

• Format: Paperback
• Language: English
• ISBN: B0HDYL6SQY
• ISBN13: 9798192248324
• Release Date: August 2026
• Publisher: Independently published
• Length: 460 Pages
• Weight: 1.76 lbs.
• Dimensions: 10.0" x 1.0" x 7.0"