Abstract: A heat-resistant alloy having a high creep rupture strength under high-temperature low-stress conditions and excellent resistance to carburization even when used at a high temperature exceeding 1100.degree. C. The alloy comprises, in % by weight, more than 0.1% to less than 1.5% of C, more than 2% to less than 3% of Si, more than 0% to less than 2% of Mn, more than 20% to less than 30% of Cr, more than 25% to less than 40% of Ni, more than 0.6% to less than 2% of Al, and the balance Fe and inevitable impurities. When required, the alloy contains at least one component selected from the group consisting of 0.01 to 0.5% of Zr, up to 0.2% of N, 0.2 to 2.0% of Nb, 0.2 to 2.0% of W and 0.01 to 03% of Ti.

Abstract: A heat-resistant alloy comprising, in % by weight, 0.3-0.8% of C, 0.5-3% of Si, over 0% to not greater than 2% of Mn, at least 23% to less than 30% of Cr, 40-55% of Ni, 0.2-1.8% of Nb, over 0.08% to not greater than 0.2% of N, 0.01-0.5% of Ti and/or 0.01-0.5% of Zr, and the balance Fe and inevitable impurities. The alloy is usable at high temperatures exceeding 1100.degree. C. with high creep rupture strength and excellent resistance to oxidation and to carburization, further exhibiting high creep deformation resistance at high temperatures and high ductility after aging.

Abstract: A method of ultrasonic flaw detection of a pipe, worth particularly for instance for a heater pipe as is used for catalytic gas reforming with steam. A transmitter probe and a receiver probe are disposed on the pipe outer surface with suitable spacing one from the other both in axial or longitudinal direction and in peripheral direction of the pipe. The transmitter probe launches ultrasonic radiation under proper angle of incidence upon the pipe outer surface at the point of entering material of the pipe, to be refracted under a particular angle of refraction so that it may then pass through the material of the pipe straight to another point upon the pipe outer surface. The receiver probe receives the ultrasonic radiation transmission echo. Flaw in the material of the pipe is detected from fluctuation of the echo, as seen upon scanning the pipe surface by moving the transmitter and receiver probes.

Abstract: A heat resistant cast iron-nickel-chromium alloy outstanding in creep fracture strength at high temperatures and resistance to thermal shock and to carburizing and containing the following components in the following proportions in terms of % by weight:C:0.3-0.6,O<Si.ltoreq.2.0,O<Mn.ltoreq.2.0,Cr:20-30,Ni:30-40,Nb+Ta:0.3-1.5,N:0.04-0.15,B:0.0002-0.004,Ti:0.04-0.50 and0.07<Al.ltoreq.0.50the balance being substantially Fe.

Abstract: A heat resistant cast iron-nickel-chromium alloy outstanding in creep fracture strength at high temperatures and resistance to thermal shock and to carburizing and containing the following components in the following proportions in terms of % by weight:C: 0.3-0.6,O<Si.ltoreq.2.0,O<Mn.ltoreq.2.0,Cr: 20-30,Ni: 30-40,W: 0.5-5.0,N: 0.04-0.15,B: 0.0002-0.004,Ti: 0.04-0.50 and0.07<Al.ltoreq.0.50the balance being substantially Fe.

Abstract: A heat resistant cast iron-nickel-chromium alloy outstanding in creep fracture strength at high temperatures and resistance to thermal shock and to carburizing and containing the following components in the following proportions in terms of % by weight:______________________________________ C 0.3-0.6, O < Si .ltoreq. 2.0, O < Mn .ltoreq. 2.0, Cr 20-30, Ni 30-40, Nb + Ta 0.3-1.5, N 0.04-0.15, B 0.0002-0.004, Ti 0.04-0.50 and Al 0.02-0.50, ______________________________________the balance being substantially Fe.

Abstract: A heat resistant cast iron-nickel-chromium alloy outstanding in creep fracture strength at high temperatures and resistance to thermal shock and to carburizing and containing the following components in the following proportions in terms of % by weight:C--0.3-0.6,O<Si.ltoreq.2.0,O<Mn.ltoreq.2.0,Cr--20-30,Ni--30-40,Nb+Ta 0.3-1.5,W--0.5-3.0,N--0.04-0.15,B--0.0002-0.004,Ti--0.04-0.50 andAl--0.02-0.50,the steel further containing 0.2 to 0.8% by weight of Mo when so desired, the balance being substantially Fe.

Abstract: A heat resistant cast iron-nickel-chromium alloy outstanding in creep fracture strength at high temperatures and resistance to thermal shock and to carburizing and containing the following components in the following proportions in terms of % by weight:C--0.3-0.6,O<Si.ltoreq.2.0,O<Mn.ltoreq.2.0,Cr--20-30,Ni--30-40,W--0.5-5.0N--0.04-0.15,B--0.0002-0.004,Ti--0.04-0.50 andAl--0.02-0.50,the balance being substantially Fe.