Most historians acknowledge that the origin of the modern threaded bolt dates back to the 15th century, the unthreaded bolt to the Roman times, with the most significant developments occurring over the past 100 – 150 years.
While there was independent development of the bolt in both Europe and The United States, World Wars I and II proved the necessity to have some consistency, and in 1948 Britain, Canada and the U.S. agreed upon the Unified thread as the standard.
Over the past 35 to 40 years, raw materials and strength testing have become more sophisticated as bolts take on more and more importance in their application in critical industries: power generation, infrastructure/bridges, original equipment manufacturing (automobiles, aircraft, trucking, etc.) and others where safety becomes a serious factor.
Thus, “steel” bolts have evolved in application to include other metals such as stainless, chrome and nickel alloys.
As both a custom OEM manufacturer and a national distributor with over 15,000 SKUs in stock, these are the most common types of bolts that will be found in the industrial marketplace: