Influence of plastic zone on fatigue crack propagation behavior of wear-resistant plate alloys
Wear-resistant plate alloy is currently recognized as one of the best construction machinery wear resistant materials, has been widely used. Wear-resistant plate alloy has excellent wear resistance, toughness and processability. Research on domestic wear-resistant plates in the past 30 years also shows that domestic wear-resistant plate alloys also have these excellent properties.
The wear resistance and fatigue properties of wear-resistant plate alloys have been studied in some countries, but the results are inconsistent. At present, there are few literature reports on the wear resistance and fatigue properties of wear-resistant plate alloys in China.
The influence of unidirectional plastic zone size on fatigue crack propagation behavior of domestic wear-resistant plate alloy was studied in saturated oxygen high temperature and high purity water with crack tip in a small yield range, in combination with foreign research results and in part with reference to ASTME647. The main chemical composition (mass fraction, %) of domestic wear-resistant plate alloy provided by a company is: Ni60.03, Cr30.38, Fe9.42, Cu0.13, Nb0.01, Mo0.07. After vacuum melting and electroslag remelting refining, the alloy obtained Φ150mm ingot, hot rolled into Φ25mm bar. After solid solution at 1050℃ and desensitization at 750℃ for 15h, the bars were processed into a compact tensile specimen (CT) with a width of 16mm. After desensitization, the yield strength of the material was 270MPa at room temperature and 220MPa at 325℃.
The effect of rp on the fatigue crack growth behavior of wear-resistant plate alloy was studied by conducting fatigue crack growth tests in air at room temperature and saturated oxygen high purity water at 325℃. The results show that:
(1) At the same frequency, the crack growth rate CGR increases with the increase of rp, but the environmental impact factor Fen does not change significantly.
(2) The cracks of domestic wear-resistant plate alloy are transgranular expansion, accompanied by a small number of branches during the expansion process, and the change of load has no obvious effect on the number of branch cracks.
(3) In saturated oxygen high temperature and high purity water, the fracture of domestic wear-resistant plate alloy is a typical wear-resistant fatigue characteristic, and crack propagation forms a ridge region with ductile fracture characteristics and a fatigue platform with brittle fatigue fracture.
