His son, Alfred (1812-87), "the Cannon King", invested heavily in new technologies (notably the Bessemer process), acquired many mines in Germany and France, and became a significant manufacturer of railway material and locomotives. He also invested in subsidized housing for his workers and started a program of health and retirement benefits. The company began to make steel cannons in the 1840s for the Russian, Turkish, and Prussian armies especially. Low non-military demand and government subsidy meant that the company specialized more and more in weapons, by the late 1880s the manufacture of armaments represented varied around 50% of the total output. When Alfred started the firm had five employees at his death there were twenty thousand - the world's largest industrial company.
Friedrich 'Fritz' Alfred (1854-1902), was somewhat eccentric and committed suicide in 1902. His daughter, Bertha Krupp (after whom the company's large howitzers or Big Berthas were nicknamed), Alfred's grand-daughter, married Gustav von Bohlen und Halbach (1870-1950) in 1906, and the family took the name Krupp von Bohlen und Halbach. He became head of the company in 1909. It had become a public company in 1903, but Bertha was almost the sole shareholder.
After Hitler came to power the Krupp works became the centre for German re-armament. In 1943, by a special order from Hitler, the company was re-converted into a family holding, and Alfried (1907-67) the son of Gustav and Bertha, took over the management. After Germany's defeat and the incapability of Gustav to be tried, Alfried was tried as a war criminal for his company's use of slave labour and he was sentenced to 12 years and ordered to sell 75% of his holdings. In 1951 as the Cold War developed and no buyer could be found he was released, and in 1953 he resumed control of the firm.
Shortly after the death of Alfried in 1967, Krupp was turned into a public corporation. His son Arndt (1938-86) relinquished his inheritance rights as well as the Krupp name, and in 1968 the Krupp family ceased to control the firm. The Villa Hügel mansion and gardens near Essen, were turned into a private charitable foundation named after Alfried as the Alfried Krupp von Bohlen und Halbach-Stiftung.
In 1999 the Krupp Group merged with its largest competitor, Thyssen AG; the combined company - Thyssen-Krupp AG, became Germany's fifth largest firm and one of the largest steel producers in the world.
The three rings of the Krupp logo are radreifen - the seamless railway wheels patented by Alfred Krupp.