COBEM99

SR28 Tribologia

Title:

TRIBOLOGICAL BEHAVIOR OF NITRIDED STAINLESS STEEL AGAINST CAST IRON UNDER SEVERE TEST CONDITION

Summary :

ABSTRACT: THIS PAPER PRESENTS LUBRICATED SLIDING WEAR TESTS RESULTS, PERFORMED IN A RECIPROCATING PIN-ON-PLATE WEAR TEST MACHINE. THE TESTS WERE PERFORMED IN TWO TEST STEPS. THE FIRST STEP WAS RUN AT 20 N LOAD AND 0.5 HZ OSCILLATION FREQUENCY; THE SECOND STEP WAS RUN AT 600 N LOAD AND 3.2 HZ OSCILLATION FREQUENCY. TWO TEST TEMPERATURES WERE USED: 100 ºC AND 150 ºC. THE PINS HAD TWO TYPES OF EDGE ROUNDNESS: FLAT AND 0.2 MM RADIUS. THE PINS MATERIAL WAS GAS NITRIDED MARTENSITIC STAINLESS STEEL AND PLATES WERE MADE OF GRAY CAST IRON, USED FOR INTERNAL COMBUSTION ENGINES PISTON RINGS AND CYLINDER LINERS MANUFACTURING. AFTER THE TESTS, IT WAS OBSERVED WEAR TRANSITION IN ALL TESTS, INDICATED BY SUDDEN INCREASE OF FRICTION COEFFICIENT VALUE. IT WAS OBSERVED MATERIAL ADHESION ON THE PINS SURFACE AND CHANGES ON PLATE ROUGHNESS. REGARDING THE TESTED PLATES SURFACES, BEFORE THE WEAR TRANSITION THE SURFACES WERE SMOOTHED AND AFTER WEAR TRANSITION THEY WERE SEVERELY ROUGHENED. THE TEST TEMPERATURE SEEMED TO HAVE NO INFLUENCE ON THE FRICTION COEFFICIENT AVERAGE VALUE BUT THE PLASTIC DEFORMED AREA WAS MORE VISIBLE UNDER HIGHER TEMPERATURE POINTING OUT A MORE SEVERE WEAR CONDITION. THE PIN EDGE GEOMETRY HAD INFLUENCE ON FRICTION AND WEAR, AND EDGE-ROUNDED PINS PRESENTED BETTER TRYBOLOGICAL BEHAVIOR. KEY WORDS: WEAR, FRICTION COEFFICIENT, RECIPROCATING TEST, TRIBOLOGY

Author :

Maru, Marcia Marie
Sinatora, Amilton
Tanaka, Deniol Katsuki

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