| 304 stainless steel is one of the most widely used stainless steel in many area,owing to its good corrosion resistance,great formability and acceptable cost.However,its corrosion resistance depend on the passive film on the surface.Once the surface has been worn,the corrosion resistance of 304 stainless steel decreases greatly.Understanding the friction and wear behavior of 304 stainless steel and improving its resistance to wear has great application value.In this work,we investigated the inflLuence of the experiment parameters to the coefficient of friction of 304 stainless steel and the evolution of the imicrostructures of worn surface and subsurface in 304 stainless steel during sliding.The main results of this work are listed as follows:1.Applied load has a great effect on the COF in run-in state and duration of this state.However,the trend of COF stays the same under different load.Steady state COF decreased with the increase of the load at first and then kept almost unchanged when the load exceed certain value.2.The initial surface topography has great effect on COF in run-in state and no effect in steady state.GNG structure has little influence on the COF trend.3.For the friction pair consist of 304 stainless steel and WC-Co ball,in steady state,the worn surface consists of wear debris insulate the two original surface.The surface of wear track consists entirely of-the α’-martensite.The ssubsurface consists ofα’-martensite,π-martensite and austenite.The grain size and volume fraction of martensite has a graded distribution.4.For 304 stainless steel,the run-in state can be divided to 3 parts:Part Ⅰ(1-4cycles):Matensite transition happens on the surface and subsurface.The phase of surface is almost entirely α’-martensite.Part 2(about 4-100cycles):Wear starts to happen on the surface.Peeling off of the surface martensite happens.Obvious oxidization was detected at this stage.Part 3(about 100-2000cycles):The roughness and the oxygen content increased and wear increased.The friction process turned to the steady state.5.GNG structure has little influence to the COF of 304 stainless steel.It is caused mainly by the easily occurring martensite transition of 304 stainless steel.At the right start,martensite phase transformation happens and cause the loss of the work hardening ability and peeling off of the surface material.So lowering the COF may relies on the suppression of martensite phase transformation of the steel. |
