Stainless Steel 13-8MO

PH 13-8 Mo* stainless Steel  bar is a materialistic precipitation/age-hardening stainless steel capable of high strength and hardness along with good levels of resistance to both general corrosion and stress-corrosion cracking. In addition, the alloy exhibits good ductility and toughness in large sections in both the longitudinal and transverse directions. The excellent properties of PH 13-8 Mo stainless are obtained through close control of chemical composition and micro structure plus specialized melting which reduces impurities and minimizes segregation. Compared to other ferrous-based materials, this alloy offers a high level of useful mechanical properties under severe environmental conditions.

13-8 Mo stainless has good fabrication characteristics and can be age-hardened by a single low temperature treatment. Cold work prior to aging increases the aging, especially for lower aging temperatures.

13-8 Mo stainless has been used for valve parts, fittings, cold-headed and machined fasteners, shafts, landing gear parts, pins, lockwashers, aircraft components, nuclear reactor components and petrochemical applications requiring resistance to stress-corrosion cracking. Generally, this alloy should be considered where high strength, toughness, corrosion resistance, and resistance to stress-corrosion cracking are required in a steel showing minimal directionality in properties.

Corrosion Resistance
In condition H 950, PH 13-8 Mo stainless has rusting resistance similar to that of Type 304 Stainless in 5 weight percent salt fog. In strongly oxidizing and reducing acids and in atmospheric exposures, the general-corrosion resistance of PH 13-8 Mo stainless approaches that of Type 304. As with other precipitation hardening stainless steels, the alloy's level of general-corrosion resistance is greatest in the fully hardened condition and decreased slightly as the aging temperature is increased. Numerous tests representing a marine environment have shown the alloy, in both the wrought and welded conditions, to have a high level of resistance to stress-corrosion cracking. For best resistance to stress-corrosion cracking, a minimum aging temperature of 1000°F (538°C) is suggested.

For optimum corrosion resistance, surfaces must be free of scale and foreign particles and finished parts should be passivated.

Typical Stress-Corrosion-Cracking Resistance in an Atmospheric Marine Environment