Ferrous seal sliding parts and producing method thereof

Abstract

A ferrous seal sliding part excellent in heat crack resistance, seizure resistance and abrasion resistance is provided. The ferrous seal sliding part has a seal sliding surface, wherein the seal sliding surface has a quench hardened layer having a structure in which a martensite parent phase forms a solid solution with carbon of 0.15 to 0.6 wt % and contains cementite dispersed therein in a content of 3 to 50% by volume.

1 . A ferrous seal sliding part having a seal sliding surface,
 wherein said seal sliding surface has a quench hardened layer having a structure in which a martensite parent phase forms a solid solution with carbon of 0.15 to 0.6 wt % and contains cementite dispersed therein in a content of 3 to 50% by volume.   
     
     
         2 . A ferrous seal sliding part having a seal sliding surface,
 wherein said seal sliding surface has a quench hardened layer having a structure in which a martensite parent phase forms a solid solution with carbon of 0.15 to 0.7 wt % and contains cementite in a content of 3 to 50% by volume and graphite in a content of 3 to 15% by volume dispersed therein.   
     
     
         3 . A ferrous seal sliding part according to any one of  claims 1  to  2 ,
 wherein said martensite parent phase has a layered structure region comprising platy cementite and martensite phases dispersed therein in an area ratio of 20% or more, whereby cementite including said platy cementite is dispersed in the martensite parent phase in a total content of 3 to 50% by volume.   
     
     
         4 . A ferrous seal sliding part according to any one of  claims 1  to  2 ,
 wherein said seal sliding surface is formed by a steel product containing carbon of 0.5 to 1.8 wt % and one or more alloy element selected from the group consisting of Cr of 0.3 to 3 wt %, V of 0.1 to 0.5 wt %, Mo of 0.3 to 2 wt % and W of 0.5 to 2 wt %.   
     
     
         5 . A ferrous seal sliding part according to  claim 2 ,
 wherein said seal sliding surface is formed by using a cast iron selected from the group consisting of a gray cast iron, a nodular graphite cast iron, a vermicular graphite cast iron and a pearlite malleable cast iron, in which said cast iron has a structure in which graphite is dispersed in a parent phase having a pearlite structure containing carbon of 2 to 4.5 wt % and further one or more alloy element selected from the group consisting of Cr of 0.5 to 4 wt %, V of 0.1 to 0.5 wt %, Mo of 0.3 to 2 wt % and W of 0.5 to 2 wt %.   
     
     
         6 . A ferrous seal sliding part according to  claim 2 ,
 wherein said seal sliding surface is formed by using a white cast iron containing carbon 2 to 4.5 wt % and further one or more alloy element selected from the group consisting of Cr of 0.5 to 4 wt %, V of 0.1 to 0.5 wt %, Mo of 0.3 to 2 wt % and W of 0.5 to 2 wt %, or a cast iron in which cementite of said white cast iron is partially graphitized.   
     
     
         7 . A ferrous seal sliding part according to any one of  claims 1  to  2 ,
 wherein an average concentration of Cr in said cementite is 2.5 to 15 wt %.   
     
     
         8 . A ferrous seal sliding part according to  claim 3 ,
 wherein cementite dispersed in said martensite parent phase contains granulated cementite having an average grain size of 0.1 to 10 μm in addition to said platy cementite.   
     
     
         9 . A ferrous seal sliding part according to any one of  claims 1  to  2 ,
 wherein said seal sliding surface contains retained austenite in a content of 10 to 50% by volume.   
     
     
         10 . A ferrous seal sliding part according to  claim 9 ,
 wherein said seal sliding surface is formed by a steel product or a cast iron containing either any one of Si of 0.5 to 3.5 wt % or Al of 0.25 to 2 wt %, or both Si and Al in a total amount of 0.5 to 3.5 wt %.   
     
     
         11 . A ferrous seal sliding part according to  claim 9 ,
 wherein said seal sliding surface is formed by a steel product or a cast iron containing both Mn and Ni in a total amount of 2 to 7 wt %.   
     
     
         12 . A ferrous seal sliding part according to  claims 1  to  2 ,
 wherein said seal sliding surface contains one or more alloy element selected from the group consisting of V, Ti, Zr, Nb, Ta and Hf in a total amount of 0.05 to 5 wt %, whereby at least any one of carbide, nitride and carbonitride of said alloy elements, having an average grain size of 0.1 to 5 μm, is dispersed in a total content of 0.1 to 10% by volume.   
     
     
         13 . A ferrous seal sliding part according to  claim 5 ,
 wherein said cast iron contains Cu of 5 to 15 wt %, whereby Cu alloy phase is dispersed in 3 to 10% by volume.   
     
     
         14 . A producing method for a ferrous seal sliding part comprising;
 a preparing step for preparing a steel product containing carbon of 0.5 to 1.8 wt % and further one or more alloy element selected from the group consisting of Cr of 0.3 to 3 wt %, V of 0.1 to 0.5 wt %, Mo of 0.3 to 2 wt % and W of 0.5 to 2 wt %; and   a quenching step for heating said steel product at a heating rate such that temperature rises from Al transformation temperature to a quenching temperature in the range of 850 to 1100° C. within 10 seconds and then rapidly cooling.   
     
     
         15 . A producing method for a ferrous seal sliding part comprising;
 a preparing step for preparing a cast iron selected from the group consisting of a gray cast iron, a nodular graphite cast iron, a vermicular graphite cast iron and a pearlite malleable cast iron, in which graphite is dispersed in a parent phase having a pearlite structure containing carbon of 2 to 4.5 wt % and further one or more alloy element selected from the group consisting of Cr of 0.5 to 4 wt %, V of 0.1 to 0.5 wt %, Mo of 0.3 to 2 wt % and W of 0.5 to 2 wt %; and   a quenching step for heating said cast iron at a heating rate such that temperature rises from Al transformation temperature to a quenching temperature in the range of 850 to 1100° C. within 10 seconds and then rapidly cooling.   
     
     
         16 . A producing method for a ferrous seal sliding part comprising;
 a preparing step for preparing a white cast iron containing carbon of 2 to 4.5 wt % and further one or more alloy element selected from the group consisting of Cr of 0.5 to 4 wt %, V of 0.1 to 0.5 wt %, Mo of 0.3 to 2 wt % and W of 0.5 to 2 wt %, or a cast iron in which cementite of said white cast iron is partially graphitized; and   a quenching step for heating said cast iron at a heating rate such that temperature rises from Al transformation temperature to a quenching temperature in the range of 850 to 1100° C. within 10 seconds and then rapidly cooling.   
     
     
         17 . A producing method for a ferrous seal sliding part according to any one of  claims 14  to  16  further comprising;
 a heat treatment step for concentrating one or more alloy element selected from the group consisting of Cr, V, Mo and W in cementite in said ferrous seal sliding part.   
     
     
         18 . A producing method for a ferrous seal sliding part according to any one of  claims 14  to  16  further comprising;
 a heat treatment step for dispersing a pearlite structure region comprising platy cementite and ferrite in an area ratio of 20% or more in a steel before quenching.   
     
     
         19 . A producing method for a ferrous seal sliding part according to any one of  claims 14  to  16 ,
 wherein said preparing step for preparing said steel product or said cast iron is a step for preparing a steel product or a cast iron containing either any one of Si of 0.5 to 3.5 wt % or Al of 0.25 to 2 wt %, or both Si and Al in a total amount of 0.5 to 3.5 wt %.   
     
     
         20 . A producing method for a ferrous seal sliding part according to any one of  claims 14  to  16 ,
 wherein said preparing step for preparing said steel product or said cast iron is a step for preparing a steel product or a cast iron containing Mn and Ni in a total amount of 2 to 7 wt %.   
     
     
         21 . A producing method for a ferrous seal sliding part according to any one of  claims 15  and  16 ,
 wherein said cast iron contains Cu of 5 to 15 wt % whereby Cu alloy phase is dispersed in 3 to 10% by volume.   
     
     
         22 . A producing method for a ferrous seal sliding part according to any one of  claims 14  to  16 ,
 wherein said heating rate is 150° C./sec or more.   
     
     
         23 . A producing method for a ferrous seal sliding part according to any one of  claims 14  to  16 ,
 wherein a pre-heating step for preheating said steel product or said cast iron at 300° C. to Al transformation temperature after said preparing step and before said quenching step.