The information accuracy of these ratings cannot be guaranteed, nor is it a complete list due to the extensive area of this field. Stainless steel fasteners are particularly susceptible to thread galling, although it also occurs in other alloys that self-generate an oxide surface film, such as aluminum and titanium. In order to understand why you shouldn’t use stainless steel and aluminum together, we first need to understand how galvanic corrosion works.
C Si Mn P S Cr Mo Ni Other 253MA S30815 0.05 1.1 - 2.0 0.8 0.040 0.030 20.0 - 22.0 10.0 - 12.0 N 0.14-0.20-0.10 Ce 0.03-0.08 Aluminum 6061-T6 Hardness, Brinell 95.0 Aluminum 7075-T6 Hardness, Brinell 150 Galling, or cold welding as it is sometimes referred to, is a form of severe adhesive wear.
These are used where toughness and corrosion resistance are of primary concern and the material should be nonmagnetic. Although wax is However, during installation users may encounter galling resulting in excessive wear, or in the worst case, seizing of the mating components, Figure 1. As a precaution, Fastenal typically adds a wax coating to stainless steel nylon insert locknuts nuts to reduce the friction. During the tightening of the fastener, pressure builds between the contacting thread surfaces and breaks down the protective oxide coatings. CoryPad (Materials) 23 May 08 10:42 It could be low torsional resistance of the internal threads (due to low shear strength or defects like porosity or cracks), it could be poor geometry (insufficient axial or radial thread engagement, off-axis threads), or it could be binding/galling. To answer your second question, I do not know of any nut/bolt compatibility table that would meet your needs. You must ensure that they have a different hardness. Thread galling is excessive mechanical contact between mating surfaces. So avoid them, or install them very slowly. Stainless Steel Chemical Compatibility Chart: Check the chemical compatibility of Stainless Steel with various chemicals, solvents, alcohols and other products.. Shop Stainless Steel. Lock nuts like these are designed to add resistance when installed and generate lots of heat. The most common stainless steel galling issue occurs with nylon insert lock nuts. Hardened steel bolts, especially when zinc plated, rarely gall. Materials used in the pump and pumping systems must be chemically compatible. Grade 304 stainless steel is generally regarded as the most common austenitic stainless steel. Bolt showing light thread galling … To help you determine which grade is right for your project, this blog will examine the difference between 304 and 316 stainless steel. This makes carbon steel notably strong, heavy, and hard. Adhesive wear occurs between two metal surfaces that are in relative motion and under sufficient load to permit the transfer of material. Stainless Steel Galling [2] Austenitic Cr-Ni stainless steels (e.g., AISI 303, 304, 316) have a tendency to gall and cold weld when in dry sliding contact. HOW TO CONTROL GALLING The measures listed are roughly in order of importance and are explained in the next section. COMPATIBILITY CHEMICAL COMPATIBILITY Chemicial Compatibility Guide The following information is intended to be used as a general guideline for pump material selection. Galling resistance of stainless steels Introduction. Adhesive wear occurs between two metal surfaces that are in relative motion and under sufficient load to permit the transfer of material. They are the austenitic, ferritic, and duplex (austenitic-ferritic) families. of the high-performance stainless steels. 304 Stainless Steel.