Abstract: A new austenitic stainless steel containing approximately 0.1-1.0 mass % of Si and not more than approximately 0.003 mass % of Al. Nonmetallic inclusions dispersed in a steel matrix are converted to MnO—SiO2—Al2O3 containing not less than approximately 15 mass % of SiO2 and not more than approximately 40 mass % of Al2O3. During steel making, molten steel is covered with basic slag and heavily deoxidized with a Si alloy whose Al content is controlled to not more than approximately 1.0 mass % in a vacuum or non-oxidizing atmosphere. The austenitic stainless steel sheet can be formed to an objective shape without the occurrence of cracking due to its decrease in susceptibility to cracking and its good formability.

Abstract: A new austenitic stainless steel containing approximately 0.1-1.0 mass % of Si and not more than approximately 0.003 mass % of Al. Nonmetallic inclusions dispersed in a steel matrix are converted to MnO—SiO2—Al2O3 containing not less than approximately 15 mass % of SiO2 and not more than approximately 40 mass % of Al2O3. During steel making, molten steel is covered with basic slag and heavily deoxidized with a Si alloy whose Al content is controlled to not more than approximately 1.0 mass % in a vacuum or non-oxidizing atmosphere. The austenitic stainless steel sheet can be formed to an objective shape without the occurrence of cracking due to its decrease in susceptibility to cracking and its good formability.

Abstract: A new austenitic stainless steel containing approximately 0.1-1.0 mass % of Si and not more than approximately 0.003 mass % of Al. Nonmetallic inclusions dispersed in a steel matrix are converted to MnO—SiO2—Al2O3 containing not less than approximately 15 mass % of SiO2 and not more than approximately 40 mass % of Al2O3. During steel making, molten steel is covered with basic slag and heavily deoxidized with a Si alloy whose Al content is controlled to not more than approximately 1.0 mass % in a vacuum or non-oxidizing atmosphere. The austenitic stainless steel sheet can be formed to an objective shape without the occurrence of cracking due to its decrease in susceptibility to cracking and its good formability.

Abstract: A new austenitic stainless steel contains 0.1-1.0 mass % of Si and not more than 0.003 mass % of Al. Nonmetallic inclusion dispersed in a steel matrix is converted to MnO—SiO2—Al2O3 containing not less than 15 mass % of SiO2 and not more than 40 mass % of Al2O3. During steel making, molten steel is covered with basic slag and strongly deoxidized with a Si alloy whose Al content is controlled not more than 1.0 mass % in a vacuum or non-oxidizing atmosphere. The austenitic stainless steel sheet can be formed to an objective shape without occurrence of cracking due to its less crack-sensitivity and good formability.

Abstract: Precipitation hardening type stainless steel comprising in % by weight, 0.03<C.ltoreq.0.08, 0.3.ltoreq.Si.ltoreq.2.5, Mn.ltoreq.4.0, 5.0.ltoreq.Ni.ltoreq.9.0, 12.0.ltoreq.Cr.ltoreq.17.0, 0.1.ltoreq.Cu.ltoreq.2.5, 0.2.ltoreq.Ti.ltoreq.1.0, and Al.ltoreq.1.0, the balance being Fe and impurities, the elements being further adjusted so thatA'=17.times.(C/Ti)+0.70.times.(Mn)+1.times.(Ni)+0.60.times.(Cr)+0.76.times. (Cu)-0.63.times.(Al)+20.871is less than 42.0, ##EQU1## is not more than 2.7, and.DELTA.Hv=205.times.[Ti-3.times.(C+N)]+205.times.[Al-2.times.(N)]+57.5.time s.(Si)+20.5.times.(Cu)+20is within the range between 120 and 210, said steel as solution treated and optionally slightly cold worked having a substantial martencite structure. The steel has a good mechanical workability before aging, and when age hardened, it develops improved hardness and toughness as well as an isotropic and improved spring performance.