Abstract: A high strength cold rolled steel strip having an excellent deep drawability comprises 0.005% by weight or less of C, 0.5% by weight or less of Si, 0.9% by weight or less of Mn, 0.05 to 0.12% by weight of P, 0.02 to 0.2% by weight of Al, 0.16% by weight or less of Ti, optionally, 1% by weight or less of Cr, and the balance consisting of Fe, the relationship (I):Ti(%)/C(%).gtoreq.4 (I)being satisfied, and is characterized in that the relationship (II):P(%).times.Ti(%).ltoreq.0.01 (II)is also satisfied.

Abstract: A high-strength, deep-drawing, cold-rolled steel sheet or strip consisting essentially of not more than 0.020% C, not more than 0.8% Si, not more than 1.5% Mn, 0.03 to 0.14% P, not more than 0.20% sol.Al, not more than 0.008% N, Ti in an amount 4 to 20 times that of (C+N), and not more than 0.0080% B, with the balance being iron and unavoidable impurities.

Abstract: A press-formable, high-strength, dual phase structure cold rolled steel sheet is disclosed. The sheet is made from steel consisting of C: 0.02-0.20%, Si: less than 0.1%, Mn: 1.0-2.0%, acid-soluble Al: 0.005-0.100%, B: more than 0.0003% and less than 0.0050% in terms of B-0.7.times.N on the condition that B/C is more than 0.03, N: less than 0.0060%, the balance being iron and incidental impurities. A process for producing such steel sheet is also disclosed.

Abstract: Al-killed steels containing 0.001-0.01% C., not larger than 1.5% Mn, 0.005-0.20% Al, not larger than 0.007% N and B in amounts determined by the ratio of B/N ranging from 0.5 to 2.5, and optionally containing not less than 1% Si and 0.04 to 0.12% P are subjected to ordinary hot and cold rolling operations, then soaked in a temperature range of from 730.degree. C. to A.sub.3 point by a continuous annealing process, and rapidly cooled from a temperature between the soaking temperature to 450.degree. C. down to a temperature not higher than 250.degree. C. at an average cooling rate not less than 60.degree. C./second, without subsequent overageing treatments, to obtain deep-drawing, non-ageing cold rolled steel sheets and strips having excellent press formability and paint bake-hardenability.

Abstract: Process for producing a deep-drawing cold rolled steel strip by continuous annealing which comprises hot rolling a steel containing not more than 0.06% C, not more than 0.40% Mn, 0.0005 to 0.0020% B, the ratio of B/N being in the range from 0.5 to 1.5 and the balance being iron and unavoidable impurities, coiling the hot rolled steel strip at a temperature not higher than 680.degree. C., cold rolling and continuously annealing the hot rolled strip.The process produces super deep-drawing cold rolled steel strips without overageing treatment.