Showing papers on "Tempering published in 1986"

Microscopic deformation behaviour of martensitic–ferritic dual-phase steels

Abstract: The deformation behaviour of the two phases of three plain carbon dual–phase steels after various treatments has been studied using a scanning electron microscope equipped with a tensile straining stage. The distribution of strains between the ferrite and martensite phases, as well as among the different grains of each phase, was observed to be inhomogeneous. The martensite/ferrite strain ratio, which defines the degree of uniformity of straining between the phases, depends on the microstructural parameters of the steels: it increases with increasing volume fraction of martensite, but decreases as the carbon content of the martensite increases. Tempering at various temperatures causes a decrease in the martensite/ferrite microhardness ratio and hence causes an increase in the strain ratio. The macroscopic strain of the specimen at which the martensite begins to deform was also found to be dependent on the microstructural parameters. Regions of applicability of the existing theories of the strength...

The influence of precipitated austenite on hydrogen embrittlement in 5.5Ni steel

Abstract: This work was undertaken to test the influence of precipitated austenite on transgranular hydrogen embrittlement in 55Ni steel Prior work has shown that the mechanism of transgranular hydrogen embrittlement in this steel is interlath separation Since the austenite that forms during the tempering of 55Ni steel precipitates on the martenite lath boundaries, it was hypothesized that the austenite might have a beneficial effect The experimental results show, however, that the precipitated austenite decreases the toughness in the presence of hydrogen The apparent mechanism is straightforward The precipitated austenite transforms to martensite in the strain field ahead of the crack tip Interlath cracks appear at the periphery of the fresh martensite particles They are apparently caused by the volume change that accompanies the martensite transformation, which imposes a tension across the lath boundary The interlath cracks link together to form the macroscopic fracture

The chemical composition of precipitated austenite in 9Ni steel

Abstract: Analytical scanning transmission electron microscopy and a novel Mossbauer spectrometry technique were used to measure the chemical composition of austenite particles which precipitate during intercritical tempering of 9Ni steel. Both techniques showed an enrichment of Ni, Mn, Cr, and Si in the austenite. A straightforward analysis involving data on both austenite composition and austenite formation kinetics suggests that the growth of austenite particles is controlled by a 3-dimensional diffusion process. The segregation of solutes to the austenite accounts for much of its stability against the martensitic transformation at low temperatures. Composition inhomogeneities develop in austenite particles after long temperings; the central regions of the particles are lean in solutes and are first to undergo the martensitic transformation. However, changes in solute concentrations of the austenite during long temperings seem too small to account for the large changes in austenite stability. It appears that some of the stability of precipitated austenite must be microstructural in origin.

Method of forming high -strength, corrosion-resistant steel.

Abstract: A high-strength, tough alloy steel is formed by heating an alloy steel comprising iron, 0.1-0.4 weight % carbon, 1-3 weight % manganese and 1-13 weight % chromium and optionally containing microalloying amounts of other metals to about 1150oC to form a stable homogeneous austenite phase, control rolling the steel at about 900oC-1100oC, followed by rapid cooling to 950oC and again rolling at that temperature and then quenching the thusly rolled steel in liquid or by air cooling. Tempering at temperatures up to about 300oC may be effected to further increase the toughness of the steel. A preferred embodiment of the present invention is illustrated in Fig. 6.

Tempering and secondary hardening of M 42 high-speed steel

Abstract: A detailed experimental study of the tempering and associated secondary hardening of M 42 high–speed steel is described. Analytical electron microscopy has been used to study the carbide re...

Production of low-alloy high-tension oil-well steel having excellent resistance to sulfide stress corrosion cracking

Abstract: PURPOSE: To produce the title oil-well steel at low cost by incorporating a specified combination of Mn, P, and Mo into steel having a specified composition, hot-working and then hardening the steel, and then tempering the steel. CONSTITUTION: The steel contg., by weight, 0.10W0.35% C, ≤0.35% Si, ≤0.005% S, 0.01W0.10% Nb, 0.2W1.5% Cr, ≤0.008% N, ≤0.028% Ti, where -0.005% ≤Ti-3.4N≤0.01%, 0.01W0.10% Al, 0.0007W0.0020% B, ≥0.1% Mo, Mn, P, and the Mo in the ratio so that the yield strength δc obtained by the equation is made higher than the actually desired yield strength YS, and the balance iron is refined. The steel is hot-worked into the desired shape. The steel material is austenitized at a temp. from (Ac 3 point + 20°C) to 1,020°C, and then hardened to obtain the material having ≥90% martensite. The steel material is subsequently tempered at a temp. from 560°C to the Ac 1 point. COPYRIGHT: (C)1987,JPO&Japio

Manufacture of turbine rotor

Abstract: PURPOSE: To obtain a rotor having satisfactory creep rupture strength and superior toughness by forging a Cr-Mo alloy steel having a regulated composition and by heating and tempering it under specified conditions. CONSTITUTION: An alloy steel consisting of, by weight, 0.1W0.3% C, ≤0.25% Si, ≤1.3% Mn, 1W13% Cr, 0.4W2.0% Mo, 0.1W0.3% V, 0.02W0.3% Nb and/or Ta, ≤0.02% T.Al and the balance Fe with accompanying impurities or further contg. one or more among 0.5W4.0% Ni, ≤2.0% W, 0.02W0.05% N and 0.001W0.04% B is forged into a rotor. After the whole of the rotor is heated to 600W1,050°C, the surface part corresponding to ≥1/2 of the radius in the direction of the axial core is rapidly heated to 900W1,100°C to produce a temp. difference in the radial direction and accelerated cooling is carried out without leveling the difference. The rotor is then tempered at 500W780°C to obtain a rotor having the desired characteristics. COPYRIGHT: (C)1987,JPO&Japio

Influence of grain boundary carbide density on impact behaviour of C–Mn–Nb–Al steels

Abstract: The influence of grain boundary carbide density on impact behaviour has been examined for C–Mn–Nb–Al steels by (i) normalizing at increasing temperatures above the Ac3, and (ii) tempering for long times below the AC1. Low normalizing temperatures (i) resulted in a large number of grain boundary carbides possibly because incomplete homogenization on austenitizing produces a high concentration of carbon at the boundaries. Raising the normalizing temperature reduced the number of grain boundary carbides as well as refining their size, but the expected improvement in impact behaviour was not realized because grain size also increased. Tempering at 680°C raised the grain boundary carbide density considerably and completely destroyed the pearlite colonies; tempering at 600°C (ii) gave a lower increase in carbide density and destroyed fewer pearlite colonies. Only small changes in grain size and grain boundary carbide thickness were noted so that the deterioration in impact behaviour obtained on temperin...

Rotor of steam turbine for high temperature use and its manufacture

Abstract: PURPOSE: To improve the notch creep rupture strength and toughness by subjecting an iron alloy contg. prescribed percentages of C, Si, Mn, Cr, Ni, W, Mo, etc. to hot plastic working, soln. heat treatment, hardening and tempering under prescribed conditions. CONSTITUTION: An iron alloy contg., by weight, 0.05W0.2% C, ≤0.1% Si, 0.05W1.5% Mn, 8W13% Cr, <1.5% Ni, 0.1W0.3% V, 0.01W0.1% Nb, 0.01W0.1% N, ≤0.02% Al, <0.5% Mo and 0.9W3% W (1/2W+Mo≥0.75 and W/Mo≥3) is manufactured by melting. The alloy is deoxidized with carbon in vacuum and remelted with electro-slag. An ingot of the resulting alloy is subjected to hot plastic working at 1,000W1,250°C, soln. heat treatment at 980W1,150°C, hardening and tempering at 650W800°C. COPYRIGHT: (C)1987,JPO&Japio

High strength weldable seamless tube of low alloy steel

Abstract: A high strength electric furnace, vacuum degassed and weldable seamless tube of low alloy steel containing 0.22 to 0.28% carbon, 1.20 to 1.4% manganese, not more than 0.035% phosphorus, not more than 0.02 sulphur, 0.15 to 0.35% silicon, 0.20 to 0.30% chromium, not more than 0.05% nickel, 0.15 to 0.60% molybdenum, 0.02 to 0.04% titanium, 0.0007 to 0.0025% boron, 0.007 to 0.050% aluminum and the balance iron. Where the pipe has a wall thickness of 11/8 inch or less the percentage molybdenum is preferably 0.15 to 0.20% whereas if the wall thickness is 1.18 inches or greater the preferred molybdenum content is 0.40 to 0.60%. The pipe is preferably heated to an austenization temperature of about 1,550° F. followed by simultaneous internal and external quenching and tempering at a temperature of about 1140° F.

Thermo mechanical precipitation hardened high tensile steel superior in cold workability and weldability and manufacture thereof

Abstract: PURPOSE: To manufacture the titled steel stock, by specifying contents of Cu, Nb in steel stock having a specified compsn. CONSTITUTION: To Fe, by weight % 0.02W0.30 C, 0.05W1.0 Si, 0.5W2.5 Mn, 0.3W2.0 Ni, 0.005W0.20 Ti, 0.003W0.050 Nb, 0.5W1.5 Cu, 0.005W0.1 Al, ≤0.0070 N, ≤0.0030 O. The steel is heated to about 950W1,100°C, then rolled at about ≤850°C by ≥about 50% accumulative draft, then immediately water cooled to ≤about 250°C by ≥about 0.5m 2 /m 2 .min water quantity density. Cu improves strength without deteriorating HAZ toughness and raises strength due to ppt. hardening in normalizing process after pipe making, hence, ≥0.5% Cu is required, but toughness is lowered with the rise thereof. Since Nb steeply deteriorates HAZ toughness due to ppt. hardening, it is regulated to the min quantity required to recrystallization suppressing effect. The steel is easily cold bent at time of use, work hardened by bending while increasing strength and attaining to the aimed strength by successive tempering, further, superior in weldability. COPYRIGHT: (C)1987,JPO&Japio

Low c-cr-mo steel used under damp steam

Abstract: PURPOSE: To provide the titled economical steel excellent in EC resistance, weldability, strength and toughness by specifying a composition consisting of C, Si, Mn, Cr, Mo, Nb, V and Fe. CONSTITUTION: A low C-Cr-Mo steel has a composition consisting of, by weight, 0.02W0.14% C, 0.45W0.90% Si, 0.30W0.80% Mn, 0.70W1.60% Cr, 0.005W0.05% Nb and/or 0.005W0.08% V and the balance essentially Fe except inevitable impurities. This steel shows excellent EC resistance and weldability when used under damp steam and is capable of improving economical efficiency by lowering preheating temp. The steel showing the above properties can be obtained by refining a steel under component regulation into the above composition, subjecting it to rolling or forging by the ordinary method and then carrying out normalizing and successive tempering or annealing. COPYRIGHT: (C)1987,JPO&Japio

Production of tempered glass

Abstract: PURPOSE:In a method of tempered glass by quenching the surface of glass heated to a temperature <= a strain point, to enable tempering by cooling with air even glass having small thickness, by using glass having a specific composition. CONSTITUTION:In a method of producing tempered glass wherein glass heated to a temperature <= a strain point is quenched, a temperature difference if formed between the surface part and the central part, and strong compression stress is thermally formed on the surface part, glass having a composition consisting of 63-75wt% SiO2, 1.5-7wt% Al2O3, 0-6wt% TiO2, 3-7wt% TiO2+ Al2O3, 5-15wt% CaO, 0-10wt% MgO, 6-20wt% CaO+MgO, 8-18wt% Na2O, 0-5wt% K2O, and 10-20wt% Na2O+K2O and <=1,150 liquid phase temperature is used. Glass having small thickness (<=3mm) which has been made with difficulty unless chemical tempering method or liquid cooling tempering is applied can be tempered by tempering with cool. Since cooling ability can be further reduced than a conventional method in glass having large thickness, cost of installation and cost of power can be lowered.

Surface hardening treatment of steel ball

Abstract: PURPOSE:To extend the rolling fatigue life of steel balls by hardening and tempering the steel balls then putting the balls into a regular polygonal steel barrel and rotating the ball around the center to drop and strike the steel balls from the upper side toward the lower side thereby hardening the surfaces of the steel balls. CONSTITUTION:The steel balls B which consist of a hardened steel and have 3-27mm diameter are hardened and tempered and thereafter the steel balls are put into the regular octagonal steel barrel 1 into the volume part of approximately <=2/3 the inside volume thereof. The barrel is then rotated around the center thereof as an axis 4 at <=80rpm, more preferably 50-60rpm rotating speed. The balls B coming to the upper side in the barrel are dropped downward and are striken against the steel balls B contained in the barrel as the barrel 1 rotates. Such rotation is repeated preferably for 60-180min. The steel balls B are striken against each other and against the inside wall of the barrel by such rotation of the barrel 1 by which the entire surface of the steel balls B is striken. A residual compressive stress layer is thus formed on the surface layer of the balls B and the life of a bearing is extended.

Process for producing high-strength seamless steel pipes excellent in sulfide stress corrosion cracking resistance

Abstract: A process for producing seamless steel pipes to be used as oil well pipes, line pipes, piping for chemical plants, etc. having both high strength and high sulfide stress corrosion cracking resistance by using inexpensive components, which process comprises increasing the content of C and minimizing the contents of impurities such as P and S, conducting quenching at a relatively slow rate of 1 to 50oC/s after heat treatment, then tempering in a relatively high temperature range of from 680oC to the Ac1 transformation point. The pipe thus obtained has a yield strength of 75 kgf/mm2 or more and excellent stress corrosion cracking resistance without causing any quenching crack.

Medium carbon air-cooled mn/b bainitic steel

Abstract: It uses Mn, B as essential alloy elements. After heat-manufactured, air-cooled hardness can be over HRC 50. Bainite/martensite duplex structures of high strengt and toughness can be gained after tempering. sigma sub 0.2 kg/sq. mm, sigma sub b is not less than 130 kg/sq. mm. It avoids quenching process saves energy, and decrease cost. The invented steel products can be used for making springs, etc. with properties reaching or exceeding 60 Si2Mn steel.

Manufacture of high strength steel with superior weldability

Abstract: PURPOSE:To manufacture a high strength steel with superior weldability by subjecting an Nb-Mo-B-N steel to on-line hardening and tempering. CONSTITUTION:The composition of a steel is composed of, by weight, 0.04-0.11 % C, =1,000 deg.C, rolled at >=800 deg.C finishing temp., quenched at once to <=200 deg.C, and tempered at the Ac1 point or below.

High tension steel plate for high heat input welding

Abstract: PURPOSE: To obtain a high tension steel plate ensuring satisfactory toughness at low temp. in the weld zone by adding B and reducing the amount of acid-sol. Al so as to accelerate the precipitation of BN and by reducing the amount of sol. B so as to prevent the deterioration of toughness. CONSTITUTION: The composition of a steel is composed of, by weight, 0.03W0.12% C, 0.05W0.4% Si, 0.7W1.6% Mn, <0.015% P, <0.01% S, 0.001W0.01% acid-sol. Al, 0.005W0.02% Ti, 0.0021W0.004% B, 0.004W0.006% N (Ti/N=1.5W35) and the balance Fe with inevitable impurities and the Ceq. is regulated to ≤0.34%. The steel is heated to 900W1,200°C and hot rolled at ≥800°C. The resulting steel plate of a prescribed thickness is rapidly cooled at once to room temp. by water cooling and then tempering is carried out at 200W450°C. COPYRIGHT: (C)1987,JPO&Japio