Investigation of the Mechanical Properties and Characteristics of Several Electrodeposited Metals on a Flexible Plate of High Carbon Steel

摘要

Aerodynamic calibration and physical measurement have shown that the flexible steel plates which form two walls of the throat and test section of the 1- by 3-foot supersonic wind tunnels have surface irregularities of great enough magnitude to cause sizable flow disturbances. Since some of the surface irregularities are as large as 0.020 inch, it was felt that simply remachining the 0.250-inch-thick steel plates would not be advisable for several reasons, one reason being that thinning the plates unevenly (0.020 to 0) would result in a nonlinear variation in thickness of 8 percent which would result in a nonuniform radius of curvature. Another objection to remachining is that once the plates are thinned, any further correcting or refinishing of the plates is made extremely marginal, if not impossible from a strength standpoint. Thus it was decided to attempt to increase the thickness of the flexible plates by the electrodeposition of some suitable metal on the steel; then to machine the plates to obtain a flat, smooth surface while at the same time retaining the original thickness of 0.250 inch. This investigation of electrodeposited metals was therefore begun, the aim being to find an electroplating material that meet the following requirements: (a) Must be capable of being deposited up to 0.030 inch thick; (b) Must have good machining qualities; (c) Must not creep under a prolonged bonding stress of 70,000 psi in basic steel; (d) Must not work harden excessively; (e) Must not develop surface cracks from repeated reversals of bonding stress; (f) Must have no serious reduction in values of mechanical properties throughout temperature range 0 to 1500 F; (g) Must have a Brinnol hardness above 50; (h) Should have a low modulus of elasticity in order to keep to a minimum the variation in moment of inertia of the basic plate; (i) Must have perfect adhesion to the basic steel, preferably without any 'in-between' plate such as copper; (j) Must not oxidize or corrode in air; (k) The electroplating process must not reduce seriously the tensile, compressive, or endurance limits of the basic steel' (l) Must be readily available commercially.