Bainitic steel for rock drilling component
a technology of bainitic steel and rock drilling, which is applied in the field of bainitic steel, can solve the problems of short service life, direct impact on the total cost of drilling operation, and rod strength
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example 1
[0084]Example 1 describes the results from field tests performed with case hardened drill rods manufactured from the inventive bainitic steel.
[0085]In a first step a heat of the inventive steel was produced. The heat was produced by melting scrap metal in an electric arc furnace, refining of the molten steel in a CLU converter and subsequently cast in 24″ moulds to ingots.
[0086]The obtained inventive steel had the following composition:
TABLE 1Chemical composition of inventive steelCSiMnPSCrNiMoVCuN0.190.870.720.0040.0091.151.660.700.200.130.009
[0087]From the inventive steel rods were produced. Some of the rods were forged into threaded female type connectors and some into threaded male type connectors.
[0088]The male and female type connectors were subjected to case hardening. In a first step the connectors were carburized in a pit furnace at a temperature of 925° C. for a time period of 5 hours, the furnace contained an atmosphere of CO and H2.
[0089]After five hours the connectors w...
example 2
[0095]In a second example, the hardness reduction of test samples from an inventive steel was determined under laboratory conditions at various reheating temperatures.
[0096]In a first step, a heat of the inventive steel was produced. The heat was produced by melting scrap metal in an electric arc furnace, refining of the molten steel in a CLU converter and subsequently casting in 24″ moulds to ingots.
[0097]The obtained inventive steel had the following composition:
TABLE 3Chemical composition of inventive steelCSiMnPSCrNiMoVCuN0.200.890.790.0110.0131.271.750.770.210.008
[0098]The ingots were rolled into bars and the bars were cut into 5 cm long cylinders, which were used as samples.
[0099]The samples were thereafter subjected to a simulated hardening treatment. This treatment included heating to austenitizing temperature, holding at austenitizing temperature for a pre-determined temperature and subsequently cooling in oil which was heated to room temperature. Thereafter the hardened sa...
example 3
[0105]In a third example a comparison was made on the surface- and core hardness of hardened and tempered samples of an alloy according to the invention and a comparative alloy. The test simulates the tempering effect that occurs in case hardened drill rods due to the heat that evolves in the couplings during drilling. For comparision, an alloy similar to the alloy disclosed in document WO97 / 27022 was selected. WO97 / 27022, discloses an alloy which is optimized for friction welding and is briefly discussed under the section “Background of the invention” of the present application.
[0106]The chemical composition of the inventive and comparative alloys are shown in table 5 below. Comp 0.09 denominates the comparative alloy and Inv 0.22 denominates the inventive alloy.
TABLE 5Chemical composiition of test alloys% C% Si% Mn% P% S% Cr% Ni% Mo% V% Cu% NComp0.190.890.300.0050.0021.251.790.750.090.0200.0020.09VInv 0.22V0.200.890.700.0600.0271.201.840.700.220.130.009
[0107]A 1 kg heat of the com...
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Abstract
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