Wear resistance of quenched and tempered AISI 4137H steel
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1.
INTRODUCTION
O F all the wear problems encountered by industry, abrasive wear accounts for more than 50 pct.' Abrasive wear occurs when hard particles interact with metal surface removing metal in the form of chips. Depending on the extent of the damage that occurs on the metal surface as a result of this interaction, the abrasion may be described as scratching, grinding, or gouging. In scratching abrasion (or low stress abrasion) the abrasive particles that act on the metal surface are not broken down in size whereas in grinding abrasion (or high stress abrasion), the stresses involved are large enough to fragment the abrasive particles.: In gouging abrasion coarse abrasive particles cut into the metal surface and remove relatively large amounts of it. Wear is a serious problem in the oil drilling industry. The drill pipe used in oil drilling consists of a central tubular section welded to couplings called tool joints. The male coupling of the drill pipe called the pin contains external threads while the female coupling called the box has internal threads. The tool joints are generally made from quenched and tempered AISI 4137H steel. If the drilling operation is conducted in sharp abrasive formations such as broken sandy shales and limes, considerable wear occurs on the outer diameter of tool joints, especially on the boxes. This wear is generally of the low stress abrasion type. As the O.D. wear occurs, the shoulder wall thickness of the box is reduced leading to a significant reduction in the torsional strength of the boxes. 3 Since a majority of drilling operations is done by rotary drilling, torsional strength of the tool joints is a very important parameter controlling their life. Resistance to wear is found to depend on certain material properties. For example, it is generally believed that wear resistance is proportional to hardness although this relationship becomes somewhat complex as the microstructure of the alloy being tested is varied. Wear resistance in steels was found to increase as the microstructure is changed progressively from ferrite to pearlite, bainite, and finally martensite. 4 Not much literature is available on the role of sulfide inclusions in the wear phenomena. It is, however, believed that inclusions in general act as internal notches and increase the wear rates in materials. 4 The purposes of the present investigation were:
MURALI D. TUMULURU is Research Metallurgist with Spang & Company, P.O. Box 751. Butler. PA 16001. Manuscript submitted December 23, 1982.
METALLURGICAL TRANSACq'IONS A
(i) to evaluate the relative wear resistance of AISI 4137H steel as a function of hardness in quenched and tempered condition using the dry sand/rubber wheel test, (ii) to evaluate the influence of the tempering temperature on the relative wear resistance of AISI 4137H steel, (iii) to evaluate the influence of cleanliness of the steel on its relative wear resistance; and finally, (iv) to evaluate the relative wear performance of improved machinability AISI 4137H steel.
II.
MATERIALS A N D
